Heavy Mineral Sands in Brazil: Deposits, Characteristics, and Extraction Potential of Selected Areas

Case Report Heavy Mineral Sands in Brazil: Deposits, Characteristics, and Extraction Potential of Selected Areas

Caroline C. Gonçalves and Paulo F. A. Braga *

Centre for Mineral Technology (CETEM), Av. Pedro Calmon 900, Cidade Universitária, Rio de Janeiro 21941-908, Brazil; [email protected] * Correspondence: [email protected]; Tel.: +55-21-3865-7222

Received: 15 January 2019; Accepted: 6 March 2019; Published: 13 March 2019

Abstract: In Brazil, heavy mineral sand deposits are still barely exploited, despite some references to Brazilian reserves and ilmenite concentrate production. The goal of this project is to characterize and investigate the potential recovery of heavy minerals from selected Brazilian placer occurrences. Two areas of the coastal region were chosen, in Piaui state and in Bahia Provinces. In all samples, the heavy minerals of interest (ilmenite, monazite, rutile, and zircon) were identified by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques and also quantified by X-ray fluorescence spectrometry (XRF) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). The total heavy minerals (THM) in the Piaui samples were 6.45% and 10.14% THM, while the figure for the Bahia sample was 3.4% THM. The recovery test of the Bahia sample, using only physical separation equipment such as a shaking table and magnetic separator, showed valuable metallurgical recoveries at around or greater than 70% for each stage, and the final concentrate of pure ilmenite was composed of up to 60.0% titanium dioxide after the differential magnetic separation. Another aim is to compile accessible information about Brazilian heavy mineral main deposits complemented with a short economic overview.

Keywords: heavy mineral sands; Brazilian occurrences; SEM analysis; XRF analysis

1. Introduction Although Brazil is considered the biggest producer of titanium dioxide in Latin America [1,2], mostly from ilmenite, studies about heavy minerals in the national territory are still scarce, limiting exploration works. The constant reference to heavy minerals such as ilmenite, zircon, and rutile as byproducts of rare earth element (REE) deposits, reveals the lack of information or a consolidated database about Brazilian heavy mineral sand deposits. The mention of defunct institutions as producers, and inaccurate grade-tonnage calculations of heavy mineral sands in international publications are common mistakes due to dispersed and hard-to-access information. Research aiming to identify new target areas and to compile accessible data seems to be a necessary step to plan future projects, considering the relevance of heavy mineral deposits in the international market. In fact, heavy mineral sands are different than other commodities in terms of exploration, development, mining, and processing, but similar in the matter of importance to industry due to their relevant physical properties [3]. Heavy mineral sand deposits are generally voluminous and near to the surface, facilitating simple exploration techniques and open cast excavation [4]. Moreover, heavy mineral processing plants are currently well-established and highly mechanized, with considerable separation efﬁciency [4]. Usually, heavy minerals from beach sands are concentrated by physical methods, ﬁrst involving gravity separation, followed by the combination of magnetic and electrostatic

Minerals 2019, 9, 176; doi:10.3390/min9030176 www.mdpi.com/journal/minerals Minerals 2019, 9, 176 2 of 15 Minerals 2019 2 of 15 ofseparation magnetic [ 5 and–8]. electrostatic Flotation is also separation used [9 , [510–],8]. often Flotation as a subsequent is also used and/or [9,10], complementary often as a subsequent stage, in and/oran effort complementary to achieve a cleaner stage, productin an effort [11 ].to achieve a cleaner product [11]. Globally,Globally, the the leading leading producer producer of of heavy heavy minerals minerals is is Australia Australia followed followed by by South South Africa Africa [12]. [12]. TheThe massive massive Australian Australian participation participation in in the the international international market market has has been been consolidated consolidated since since the the 1960s1960s [11]. [11]. Furthermore, Furthermore, according according to to Gosen Gosen et et al. al. (2016) (2016) [4], [4], Chi Chinana had had the the biggest biggest production production of of ilmeniteilmenite concentrate concentrate in in 2014. 2014. In In Brazil, Brazil, however, however, the the deposits deposits of of heavy heavy mineral mineral sands sands are are largely largely not not exploited,exploited, with with the the only only active active operation operation being being the the Guaju Guaju mine mine (Cristal (Cristal Group) Group) located located in in Paraiba Paraiba Province.Province. The The main main mine mineralsrals processed processed from from that that mine mine are are ilmenite, ilmenite, rutile, rutile, zircon zircon,, and and kyanite. kyanite. Likewise,Likewise, the company company Industrias Industrias Nucleares Nucleares do Brasildo Brasil (INB), (INB), in Rio in de Rio Janeiro de JaneiroProvince, Province, still produces still producesilmenite, ilmenite, zircon, rutile, zircon, and rutile monazite, and monazite concentrates concentrates for sale as for is. sale as is. TheThe importan importancece of of coastal coastal heavy heavy mineral mineral deposits deposits as as sources sources of of rutile, rutile, ilmenite ilmenite,, and and zircon zircon for for industry,industry, and and their their worldwide worldwide uses uses,, have have always always been been mentioned mentioned [13]. [13 These]. These deposits deposits are area source a source of titaniumof titanium and and zirconium zirconium [4] as [4 ]well as well as rare as rare earth earth elements elements (REE (REEs),s), and andare areoften often overlooked overlooked [14]. [ 14In]. Brazil,In Brazil, some some found found occurrences occurrences of monazite of monazite and its and secondary its secondary products products (ilmenite, (ilmenite, zircon, zircon,and rutile) and arerutile) along are the along coastline the coastline [15,16], [15 and,16], mostand most studies studies have have been been specifically speciﬁcally developed developed to to fi ﬁndnd REE REE depositsdeposits (Figure(Figure1 ).1). Practically Practically all all of them of them are located are located in the in southeast the southeast region as region described as described in Louwerse in Louwerse(2016) [17 ].(2016) [17].

FigureFigure 1. 1. RareRare earth earth elements elements ( (REEs)-bearingREEs)-bearing mineral mineral occurrences occurrences along along the the Brazilian Brazilian coastline coastline and and areasareas licensed licensed by by the the National National Department Department of of Mineral Mineral Production Production (DNPM) (DNPM) for for extraction extraction of of REE REEs.s. AdaptedAdapted from from [15,16]. [15,16].

AsAs cited cited by CETEMCETEM (2014)(2014) [ 18[18],], the the presence presence of surfaceof surface and and submerged submerged deposits deposits of ilmenite, of ilmenite, rutile, rutile,zircon, zircon and, monazite and monazite is along is along nearly nearly the entire the entire Brazilian Brazilian littoral, littoral, from from Para Para to Rio to Rio Grande Grande do Sul.do Sul.In these In these regions, regions, including including the northern the northern portion, other portion, proﬁtable other placer profitable deposits placer of heavy deposits mineral of heavy sands mineralare/were sands being are/were exploited, being like in exploited, Sao Francisco like de in Itabapoana Sao Francisco (Rio de de Janeiro), Itabapoana Mataraca (Rio (Paraiba), de Janeiro), and MataracaPrado (Bahia). (Paraiba), However, and Prado according (Bahia). to Krishnamurthy However, according and Gupta to Kr (2016)ishnamurthy [19], mineral and sand Gupta mining (2016) in [Brazil19], mineral is oriented sand to mining the thorium in Brazil content is oriented of monazite, to the inthorium contrast content with other of monazite, countries, in where contrast monazite with otheris a secondary countries, product where monazite rather than is ilmenite,a secondary rutile, product and zircon. rather In than fact, ilmenite, in the past, rutile exploration, and zircon. efforts In fact,for ﬁndingin the past, monazite explora depositstion eff wereorts for connected finding withmonazite the intention deposits of were producing connected REE with oxides the for intention nuclear ofpurposes producing [18 ]. REE INB oxides for instance, for nuclear which purposes has mined [18 and]. INB processed for instance, heavy minerals which has in the mined northern and processedcoastal region heavy of mineralsRio de Janeiro, in the is northern recognized coastal for its region monazite of Rio sand de deposits. Janeiro, is The recognized Heavy Minerals for its monaziteUnit of Buena sand isdeposits. the most The relevant Heavy plant Minerals for monazite Unit of Buena concentration, is the most but relevant has been plant decommissioned. for monazite concentrationNowadays, monazite, but has concentrates been decommissioned. come from old Nowadays, mining activities monazite and concentrates will likely become produced from old for miningtwo or activities three more and years. will likely be produced for two or three more years. The production of titanium dioxide in Brazil started in 1971, and at present, heavy minerals such as ilmenite, rutile, kyanite, and zircon [20,21] are extracted at the Guaju mine [5] by the Cristal Group. The presence of monazite is also well known on the deposit [22,23]. Nevertheless, their

Minerals 2019, 9, 176 3 of 15

The production of titanium dioxide in Brazil started in 1971, and at present, heavy minerals such Minerals 2019 3 of 15 as ilmenite, rutile, kyanite, and zircon [20,21] are extracted at the Guaju mine [5] by the Cristal Group. Thereserves presence may of be monazite exhausted is also within well a knownfew years. on theCurrently, deposit [some22,23 ].eff Nevertheless,orts for an independent their reserves national may beproduction exhausted of within titanium a few mineral years. concent Currently,rates some have efforts been made for an by independent Rio Grande national Mineraçao production S. A., based of titaniumon a forecast mineral for concentratesgrowth of the have Brazilian been made ilmenite by Rio consumption. Grande Mineraçao They estimate S. A., based an annual on a forecast production for growthof 323,000 of the tons Brazilian of heavy ilmenite mineral consumption. concentrates, They 275,000 estimate being anilmenite, annual 10,000 production rutile, of and 323,000 38,000 tons zircon of heavy[24]. mineral concentrates, 275,000 being ilmenite, 10,000 rutile, and 38,000 zircon [24]. AA comparison comparison of of Brazilian Brazilian heavy heavy mineral mineral resources resources and production and production with other with countries other countries is given is everygiven year every by theyear National by the National Department Department of Mineral of Production Mineral Production (DNPM) [1 (].DNPM Data compilation) [1]. Data compilation from 2009 tofrom 2015 2009 for ilmenite, to 2015 for rutile, ilmenite, and zircon rutile, are and shown zircon in Figureare shown2. Although in Figure Brazil 2. Although has modest Brazil resources has modest and productionresources andof zircon production concentrate, of zircon in the concentrate national market, in the of national heavy mineral market sands, of heavy ilmenite mineral and rutile sands, concentratesilmenite and are rutile considered concentrates the main are considered products. Indeed,the main in products more recent. Indeed, data in [25 more], Brazilian recent ilmenitedata [25], resourcesBrazilian are ilmenite still considered resources small, are still only considered about 5.6% small, of global only resources. about 5.6% As of described global resources. in Technical As Reportdescribed 36 [26in ],Technical Brazilian Report production 36 [26 of], Brazilian titanium production concentrates of (ilmenitetitanium plusconcentrates rutile) has (ilmenite oscillated plus considerably,rutile) has oscillated with the considerably, most relevant with decline the sincemost 1986relevant occurring decline in since 2001, 1986 when occurring production in 2001, was onlywhen 64,450production tons. The was highest only 64,450titanium tons. production, The highest however, titanium was in production, 2007 with 226,865 however, tons, was and in in 2007 2015, with the most226,865 recent tons, data, and was in 2015, 81,000 the tons most [1]. recent data, was 81,000 tons [1]. Furthermore,Furthermore, the the production production of of zircon, zircon, from from 2003 2003 to to 2015, 2015, varied varied from from 16,000 16,000 to to 28,000 28,000 tons tons per per yearyear and and the the assigned assigned resources resources decreased decreased from from 74 74 Mt Mt in in 2009 2009 to to approximately approximately 22,6000 22,6000 tons tons in in 2015 2015 (Figure(Figure2). 2). Placer Placer deposits deposits are are considered considered the the secondary secondary source source of of zircon zircon in in Brazil, Brazil, since since primary primary sourcessources are are those those related related with with intrusive intrusive alkaline alkaline rocks rocks [1]. The[1]. monaziteThe monazite resources resources and production and production data aredata always are always included included as one of as the one sources of the of sources REEs and of REE theirs and specific their quantification specific quanti isfi morecation complex. is more Thecomplex. preliminary The preliminary calculated Braziliancalculated monazite Brazilian resources monazite areresources 22 Mt [ 1are]. The 22 Mt production [1]. The pr ofoduction monazite of concentrates,monazite concentrates however, has, however, significantly has significantly oscillated, falling oscillated, from 1,173falling tons from in 1,173 2007 totons 249 in tons 2007 in to 2010. 249 Moretons recentin 2010. data More showed recent a productiondata showed of 600a production tons in 2013 ofand 600 notons production in 2013 and in 2015 no production [1]. Although in this2015 was[1]. aAlthough small production, this was a all small monazite production, concentrate all monazite produced concentrate by INB in produced this period by fromINB in 2003 this to period 2015 wasfrom exported 2003 to [20151]. was exported [1].

Figure 2. Cont.

MineralsMinerals2019 2019, 9 , 176 44 ofof 15 15

FigureFigure 2. 2. BrazilianBrazilian resources resources and and the the production production of of ilmenite, ilmenite, rutile, rutile, and and zircon zircon concentrates, concentrates, in in comparisoncomparison with with the the main main global global producers. producers. Compiled Compiled from from [1 [1].]. Therefore, a project for the characterization and recovery of heavy minerals from selected Brazilian Therefore, a project for the characterization and recovery of heavy minerals from selected placer occurrences was developed. The study was aimed at compiling accessible information about Brazilian placer occurrences was developed. The study was aimed at compiling accessible the main Brazilian deposits of heavy mineral sands [15,16,27–32], complemented by a short economic information about the main Brazilian deposits of heavy mineral sands [15,16,27–32], complemented overview, highlighting the presence of ilmenite, zircon, monazite, and rutile. Two areas of the Brazilian by a short economic overview, highlighting the presence of ilmenite, zircon, monazite, and rutile. coastal region were chosen for characterization studies. Two areas of the Brazilian coastal region were chosen for characterization studies. 2. Study of Potential Areas 2. Study of Potential Areas 2.1. Sampling Areas 2.1. Sampling Areas Two potential areas were chosen based on previous studies [27,30] and recent exploration worksTwo [31]. potentialThese areas areas are located were chosen in Luis ba Correia/Piauised on previous and Prado/Bahia. studies [27,30 Three] and samples recent exploration have been collected,works [31 two]. These of them areas in are Luis located Correia in (LC Luis and Correia/Piaui LP) and one and in PradoPrado/Bahia. (PA) (Figure Three3 ).samples In Luis have Correia, been thecollected, samples two were of them collected in Luis by theCorreia grab (LC sample and technique,LP) and one and in Prado due to (PA) a limited (Figure amount 3). In Luis of collected Correia, materialthe samples (at around were collected 9.0 kg for by each the sample)grab sample and thetechnique, lack of and representativeness, due to a limited LC amount and LP of samplescollected werematerial characterized (at around just 9.0 inkg order for each to identify sample) potential and the heavylack of mineralsrepresentativeness for future,works. LC and Conversely, LP samples aroundwere characterized 0.5 tons of heavy just mineralin order sands to identify were collected potential in heavy Prado minerals (PA sample) for byfuture the trenchingworks. Conversely, sampling methodaround (at 0.5 around tons of 1.5 heavy m depth). mineral The spot sands was were chosen collected supported in Prado by the (PA local sample company’s) by the geochemical trenching studies.sampling The method PA sample (at around was also 1.5 subjected m depth) to. The recovery spot was tests. chosen supported by the local company’s geochemicalThe presence studies of.heavy The PA minerals sample inwas Luis also Correia subjected region to recovery was confirmed tests. in the 1980s when the SamitreThe Company presence surveyed of heavy this minerals occurrence in Luis and Correia classified region it as was a medium confirmed deposit, in the with 1980s resources when the of approximatelySamitre Company 1,500,000 surveyed tons [this30]. Accordingoccurrence toand the classi Brazilianfied it Mineral as a medium Resources deposit, Company with resources (2014) [29 ],of Luisapproximately Correia district 1,500 is,000 classified tons [30 as]. coastal According deposits to the with Brazilian fine sand. Mineral Moving Resources dunes (Figure Company3a,b) (2014) and paleodunes[29], Luis Correia are composed district mainlyis classified of selected as coastal quartz deposits or quartz-feldspar with fine sand. sediments Moving formeddunes (Figure during 3 thea,b) Quaternaryand paleodunes Period are [28 ]. composed mainly of selected quartz or quartz-feldspar sediments formed duringPrado the is Quaternary also characterized Period by[28 an]. accumulation of sediments of the Quaternary Period. Conversely, otherPrado authors is [27 also] mentioned characterized that by the an geological accumulation context of of sediments this area of may the be Quaternary described Period.by an accumulationConversely, other of sediments authors [ from27] mentioned the Cretaceous that the to geological the Tertiary context Periods of this associated area may with be Archeandescribed rocks,by an which accumulation could have of been sediments a source from of heavy the minerals. Cretaceous Additionally, to the Tertiary north Prado Periods is in associated direct contact with withArchean Barreiras rocks, Group which where could sediments have been are a source classified of heavy as well minerals. as selected Additionally, coarse sand north (Figure Prado3c) [ is29 ].in Aboutdirect heavy contact mineral with Barreiras occurrences, Group Louwerse where (2016) sediments [17] cited are classified that Prado as region well hasas selected monazite coarse resources sand (approximately(Figure 3c) [29]. 4,464 About tons) heavy composed mineral of occurrences, 19.98% REE Louwerse oxides, including (2016) [17] the cited presence that ofPrado xenotime region and has allanitemonazite minerals resources [17]. In (approximately fact, Cumuruxatiba 4,464 and tons) Alcobaça, composed near of to 19.98% Prado, have REE been oxides, sources including of heavy the mineralspresence since of xenotime the 18th and century allanite when minerals monazite [17]. was In sentfact, toCumuruxatiba Europe [27]. and Alcobaça, near to Prado, have been sources of heavy minerals since the 18th century when monazite was sent to Europe [27].

Minerals 2019, 9, 176 5 of 15 Minerals 2019 5 of 15

FigureFigure 3. 3. SampledSampled areas: areas: LP LP (a (a),), LC LC (b (b),), and and PA PA (c (c).). 2.2. Analytical Tools and Methods 2.2. Analytical Tools and Methods Samples were characterized in three main parts: (1) the raw material; (2) sink dried aliquots Samples were characterized in three main parts: (1) the raw material; (2) sink dried aliquots separated by methylene iodide (d = 3.32 g·cm−3) as a heavy medium and by a Frantz Isodynamic separated by methylene iodide (d = 3.32 g·cm−3) as a heavy medium and by a Frantz Isodynamic Separator (Model L-1, S.G. Frantz Co., Moorestown, NJ, USA) (transverse slope θ set at 15◦), Separator (Model L-1, S.G. Frantz Co., Moorestown, NJ, USA) (transverse slope θ set at 15°), and (3) and (3) products and tailings recovered from test steps. Techniques and equipment are: optical products and tailings recovered from test steps. Techniques and equipment are: optical microscopy, microscopy, chemical analysis by X-ray ﬂuorescence spectrometry (XRF, Axios Max Rh emission chemical analysis by X-ray fluorescence spectrometry (XRF, Axios Max Rh emission spectrometer, spectrometer, Malvern Panalytical Ltd., Royston, UK) and by inductively coupled plasma optical Malvern Panalytical Ltd., Royston, UK) and by inductively coupled plasma optical emission emission spectrometry (ICP-OES, Ultima 2 spectrometer, HORIBA Instruments Brasil, Ltda., Sao Paulo, spectrometry (ICP-OES, Ultima 2 spectrometer, HORIBA Instruments Brasil, Ltda., Sao Paulo, Brazil); mineralogical analysis by X-ray diffraction (XRD, AXS D4 Endeavor co-emission diffractometer, Brazil); mineralogical analysis by X-ray diffraction (XRD, AXS D4 Endeavor co-emission Bruker, Karlsruhe, Germany) and by scanning electron microscopy (SEM, TM 3030 Plus tabletop diffractometer, Bruker, Karlsruhe, Germany) and by scanning electron microscopy (SEM, TM 3030 microscope, Hitachi, Tokyo, Japan) with energy dispersive X-ray analysis (EDX); and density Plus tabletop microscope, Hitachi, Tokyo, Japan) with energy dispersive X-ray analysis (EDX); and measurements by pycnometry (AccuPyc II 1340, Micromeritics, Norcross, GA, USA) with helium density measurements by pycnometry (AccuPyc II 1340, Micromeritics, Norcross, GA, USA) with as analyzing gas. It is important to note that for XRF and XRD analysis, all samples tested were helium as analyzing gas. It is important to note that for XRF and XRD analysis, all samples tested homogenized in longitudinal piles, and then quartered using a rotating laboratory sample divider. were homogenized in longitudinal piles, and then quartered using a rotating laboratory sample For XRD, representative aliquots of 3 g of each sample were ground with 10 mL of deionized water divider. For XRD, representative aliquots of 3 g of each sample were ground with 10 mL of using a McCrone mill (Microne micronising mill, Glen Creston, Westmont, CA, USA) for 10 min, and deionized water using a McCrone mill (Microne micronising mill, Glen Creston, Westmont, CA, after dried. For XRF, representative aliquots of 30 g were ground using a laboratory pulverizer (carbide USA) for 10 min, and after dried. For XRF, representative aliquots of 30 g were ground using a ball mill, pulverisette, Fritsch, Idar-Olberstein, Germany) and then separated into 5 g aliquots using laboratory pulverizer (carbide ball mill, pulverisette, Fritsch, Idar-Olberstein, Germany) and then the same rotating laboratory sample divider. separated into 5 g aliquots using the same rotating laboratory sample divider. 2.3. Recovery Test 2.3. Recovery Test A pilot plant test using gravity and magnetic separation methods (Figure4a) was performed on aA 28.7 pilot kg plant PA sample. test using Before gravity all tests,and magnetic a wet cleaning separation stage methods was carried (Figure out 4 duea) was to aperformed great amount on aof 28.7 organic kg PA material, sample. Before which all was tests, partially a wet responsiblecleaning stage for was the carried dark color out due (Figure to a3 c).great The amount cleaned of organicsample material, still had 3.0%which of was organic partially material responsible measured for in the terms dark of color loss on (Figure ignition 3c). (LOI) The usingcleaned a TGA-701 sample stillThermogravimetric had 3.0% of organic Analyzer material (LECO me Instrumentosasured in terms Ltda., of loss Rio de on Janeiro, ignition Brazil). (LOI) using Then, a the TGA cleaned-701 Thermogravimetricsample was wet screened Analyzer using (LECO a 297 Instrumentosµm aperture Ltda. and, theRio undersizede Janeiro (pulp, Brazil with). Then, 35% the solids) cleaned sent sampleto a Super was wet Duty screened Diagonal using Deck a 297 shaking µm aperture table (slope and the set undersize at 10◦). Furthermore, (pulp with 35% the solids) heavy sent fraction to a Supwaser separated Duty Diagonal in an Inbras Deck high shaking intensity table magnetic (slope set separator at 10°). Furthermore, with a magnetic the ﬁeld heavy strength fraction of was4.5 T separated(Tesla). However, in an Inbras the nonmagnetic high intensity concentrate magnetic separator had to be with separated a mag againnetic field from strength light minerals of 4.5 by T (Tusingesla). a However, shaking table. the nonmagnetic In addition, the concentrate magnetic concentrate had to be separated (about 800.0 again g) was from wet light screened minerals using by a using212 µ am shaking aperture, table. and In then addition, each aliquotthe magnetic (oversize concentrate and undersize) (about 800.0 was separatedg) was wet at screened the same using Inbras a 212high µm intensity aperture, magnetic and then separator, each aliquot changing (oversize its belt and speed undersize) (Figure4 wasb). The separated belt speed at the was same adjusted Inbras to high intensity magnetic separator, changing its belt speed (Figure 4b). The belt speed was adjusted to 50 rpm (rotations per minute) for each test, reaching 300 rpm maximum. Due to a higher magnetic susceptibility, minerals such as ilmenite should be recovered at the highest belt speed.

Minerals 2019, 9, 176 6 of 15

50 rpm (rotations per minute) for each test, reaching 300 rpm maximum. Due to a higher magnetic Mineralssusceptibility, 2019 minerals such as ilmenite should be recovered at the highest belt speed. 6 of 15

FigureFigure 4. 4. MainMain recovery recovery test test flow ﬂow sheet sheet ( (aa)) and and differential differential magnetic magnetic separation separation flow ﬂow sheet ( b).

3.3. Results Results and and Discussion Discussion

3.1.3.1. Characterization Characterization and and Identification Identification of Heavy Minerals TheThe ssamples’amples’ physical physical properties properties are are given given in in Table Table 1 1.. Specifically Specifically in this this study, study, in in order order to to facilitatefacilitate characterization characterization works, works, avoiding avoiding excessive excessive contamination contamination by by silicates, silicates, total total heavy heavy mineral mineral quantificationquantification was was done done using methylene iodide. iodide. Consequently, Consequently, al alll minerals minerals which which have have a a density · −3 · −3 higherhigher than 3.32 g·cm−3 werewere considered considered as as heavy heavy minerals (THM). Those heavier thanthan 3.323.32 gg·cmcm−3,, which were recoveredrecovered upup to to 1.3 1.3 T T magnetic magnetic field field strength strength by by a Frantz a Frantz Isodynamic Isodynamic Separator, Separator, were were also alsoconsidered considered as total as total magnetic magnet heavyic heavy minerals. minerals.

Table 1. Classiﬁcation of the three samples. Table 1. Classification of the three samples.

PropertyProperty LCLC LP PA PA TotalTotal heavy heavy minerals minerals (THM) (THM) (%) (%) 6.456.45 10.14 3.403.40 Total magnetic magnetic heavy heavy minerals minerals (%) (%) 65.6065.60 64.40 94.1294.12 d80 passing size (µm) 190 400 730 Slimesd80 passing (−45 µ m)size (%) (µm) 0.31190 0.11400 730 0.10 Slimes (−45 µm) (%) 0.31 0.11 0.10

BasedBased on on the the characterization characterization analysis, analysis, both both areas areas show show the four the minerals four minerals of interest, of i.e.,interest, monazite i.e., monazite(Mnz), rutile (Mnz), (Rt), rutile zircon (Rt), (Zrn), zircon and (Zrn), ilmenite and (Ilm), ilmenite the (Ilm), latter themineral latter being mineral the being most abundant. the most abundant.Additionally, Additionally, XRD and Rietveld XRD andquantification Rietveld werequantification performed. were Using performed. the software Using Bruker the AXS software Topas, Bruker(version AXS 5), the Topas, phases (version were quantified. 5), the Theirphases crystalline were quantified. structures Their were identified crystalline using structures the following were identifieddatabases: using Bruker the AXS, following Inorganic databases: Crystal StructureBruker AXS, Database Inorganic (ICSD) Crystal [33], andStructure Crystallographic Database (ICSD) Open [33]Database, and Cryst (COD)allographic [34]; refining Open variables Database were (COD) adjusted [34]; refining to those variables corresponding were adjustedto the equipment to those correspondingstandard. The result to the for equipment the raw material standard. demonstrated The result 0.7% for ilmenite,the raw 0.2% material monazite, demonstrated 0.3% rutile, 0.7% and ilmenite,0.2% zircon 0.2% for monazite, LC; the LP 0.3% sample rutile was, and composed 0.2% zircon of 4.4%for LC; ilmenite, the LP 1.6%sample monazite, was compo 0.4%sed rutile, of 4.4% and ilmenite,1.3% zircon. 1.6% These monazite, two samples 0.4% rutile were, also and composed 1.3% zircon. of minerals These two such samples as actinolite, were epidote,also composed muscovite, of mineralskyanite (Ky), such staurolite as actinolite, (St), and epidote, leucoxene muscovite, (Lcx). Details kyanite of (Ky), some staurolite identified (St) minerals, and leucoxene from LP and (Lcx). LC Details of some identified minerals from LP and LC are given in Figure 5. Due to the proximity of the sampled points, their mineralogical assemblages are quite similar. However, for the PA sample, although the Rietveld method allows the quantification of the amount of amorphous minerals [35], the results were not precise especially for minor minerals such as monazite and rutile due to the

Minerals 2019, 9, 176 7 of 15 are given in Figure5. Due to the proximity of the sampled points, their mineralogical assemblages are quite similar. However, for the PA sample, although the Rietveld method allows the quantiﬁcation of theMinerals amount 2019 of amorphous minerals [35], the results were not precise especially for minor7 of minerals 15 such as monazite and rutile due to the great presence of light minerals (higher than 96% in terms of great presence of light minerals (higher than 96% in terms of mass distribution), and consequently, massXRD distribution), interpretations and were consequently, not considered. XRD interpretations were not considered.

(a) (b) (c)

FigureFigure 5. Examples5. Examples of of some some heavy heavy minerals minerals identiﬁedidentified via optical microscopy microscopy of of LC LC (a), (a LP), LP (b) ( band) and PA (c) samples.PA (c) samples Note:. Ilm:Note: ilmenite, Ilm: ilmenite, Ky: kyanite, Ky: kyanite, Lcx: leucoxene,Lcx: leucoxene, Mnz: Mnz: monazite, monazite, Rt:rutile, Rt: rutile, St: staurolite St: andstaurolite Zrn: zircon. and Zrn: zircon.

TheThe separation separation by by a a heavy heavy mediummedium (methylene (methylene iodide) iodide) followed followed by a by separation a separation using using a Frantz a Frantz Isodynamic Separator allowed a better observation of those heavy minerals present in the samples. Isodynamic Separator allowed a better observation of those heavy minerals present in the samples. This stage provided important information about mineral alterations and inclusions, which can This stage provided important information about mineral alterations and inclusions, which can determine further beneficiation tests. An average of 65% by weight of LC and LP sink fractions were determinecomposed further of magnetic beneficiation heavy minerals. tests. An Ilmenite average (Ilm) of 65% was by the weight most abundant of LC and mineral LPsink in both fractions weresamples composed and concentrated of magnetic atheavy 0.450 T minerals. fraction (Figure Ilmenite 6a); (Ilm)magnetite was was the also most detected abundant in this mineral fraction. in both samplesThe ilmenite and concentrated grains are extremely at 0.450 altered T fraction sometimes (Figure in6 a);pseudorutile magnetite and was anatase also detected (grain boundaries), in this fraction. Theas ilmenite reported grains by [3 are6], extremelyand also leucoxene altered sometimes (Figure 5a in,b). pseudorutile These ilmenite and grains anatase showed (grain selective boundaries), as reportedalteration by (Figure [36], and6a) as also well. leucoxene The boundary (Figure alterations5a,b). These might ilmenite be due grains to the showedreducing selective conditions alteration of (Figurethe 6 geologicala) as well. environment The boundary [37 alterations]. However, might although be due these to the alterations reducing did conditions not affect of the ilmenite geological environmentrecovery at [ 37the]. theoretical However, althoughmagnetic field these strength alterations at 0.450 did notT, ilmenite affect ilmenite was also recovery retained at at the 0.675 theoretical T. magneticIlmenite field wasstrength usually found at 0.450 in T,pure ilmenite form but was a minor also retained presence at of 0.675 manganese T. Ilmenite (Mn) washas also usually been found observed by EDX for both Luis Correia samples. Minerals such as monazite, stautolite, actinolite, in pure form but a minor presence of manganese (Mn) has also been observed by EDX for both Luis and amphiboles were founded at 0.950 T fraction. In addition, the nonmagnetic fraction contains Correia samples. Minerals such as monazite, stautolite, actinolite, and amphiboles were founded at mostly prismatic and rounded zircon (Zrn) with kyanite (Ky) inclusions, and rounded and prismatic 0.950rutile T fraction. (Rt) (Figure In addition, 6b). Despite the the nonmagnetic fact that zircon fraction composition contains is mostlynot comparable prismatic toand the theoretic roundedal zircon (Zrn)due with to the kyanite presence (Ky) of niobium inclusions, (Nb) and and roundedaluminum and (Al), prismatic the hafnium rutile (Hf) (Rt) and (Figurezirconium6b). (Zr) Despite ratio the factare that 0.04 zircon for both composition samples as is notdescribed comparable elsewhere to the [38 theoretical]. Al-silicates due such to asthe kyanite presence present of niobium in the (Nb) andnonmagnetic aluminum (Al), fractions the hafnium of LC sample, (Hf) and for zirconium instance, (Zr) are ratio coarser are than 0.04 for 74 both µm, samplesfacilitating as their described elsewhereseparation [38 by]. Al-silicates size from zircon; such asin kyaniteother deposits present this in separation the nonmagnetic is more complicatedfractions of [3 LC8] sample, and a for instance,flotation are stage coarser is needed than 74[10].µm, facilitating their separation by size from zircon; in other deposits this separation is more complicated [38] and a flotation stage is needed [10].

Minerals 2019, 9, 176 8 of 15 Minerals 2019 8 of 15

(a)

(b)

FigureFigure 6. 6.SEM SEM images images of of LC LC heavy heavy mineralsminerals retainedretained at at 0.450 0.450 T T ( (aa) )and and the the nonmagnetic nonmagnetic fraction fraction (b) ( b) separatedseparated by by a Frantz a Frantz magnetic magnetic separator separator and and their their respective respective XRD XRD spectra spectra showing showing the main the mineral main of themineral fraction. of the fraction.

Minerals 2019 9 of 15

Minerals 2019, 9, 176 9 of 15 MineralsSEM 2019 image mapping of PA by element (Ti, P, Fe, Zr, and Si) of the sink fraction is shown below9 of 15 (Figure 7a). This image confirms the high presence of ilmenite rather than other heavy minerals such as zirconSEM andimage monazite. mapping In of of thisPA PA by analysis, element no (Ti, rutile P, Fe, was Zr,Zr, andfound.and Si)Si) ofMonaziteof the sink (Figure fraction 7b) is shownis the below main mineral(Figure(Figure7 7retaineda).a). ThisThis imageimageat 1.3 conﬁrmsTconfirms and according thethe highhigh to presencepresence EDX data ofof ilmeniteilmenitecomposed ratherrather of REE thanthan Ce otherother (24.4%), heavyheavy La mineralsminerals (15.9%), suchsuch Nd (6.1%),as zircon zircon and and and Th monazite. monazite.(7.9%) on In In thisaverage. this analysis, analysis, Monazite no rutile no rutilegrain was found.wasshapes found. Monaziteare very Monazite (Figurevariable (Figure7b) and is the 7canb main) isvary the mineral from main elongatedretainedmineral retained at to 1.3 subrounded. T andat 1.3 according T and In addition,according to EDX in to data theEDX composednonm dataagnetic composed of REEfraction, of Ce REE (24.4%), minerals Ce (24. La 4%),such (15.9%), Laas (15.9%),zircon Nd (6.1%), and Nd rutileand(6.1%) Th are, (7.9%)and mainly Th on (7.9%)composed average. on Monaziteaverage.of 38.0% ZrO Monazite grain2 and shapes 53.1% grain are SiO shapes very2, and variable are 89.3% very and TiO variable can2, respectively. vary and from can elongated vary from to subrounded.elongated to Insubrounded. addition, in In the addition, nonmagnetic in the fraction, nonmagnetic minerals fraction, such as minerals zircon and such rutile as zircon are mainly and composedrutile are mainly of 38.0% composed ZrO2 and of53.1% 38.0% SiO ZrO2,2 andand 89.3%53.1% TiOSiO22,, respectively.and 89.3% TiO2, respectively.

(a) (b)

Figure 7. SEM image mapping of PA sink fraction (a) and SEM image of sink fraction retained at 1.3 (a) (b) T (b). Figure 7. SEMSEM image image mapping mapping of of PA PA sink sink fraction fraction (a ()a and) and SEM SEM image image of sink of sink fraction fraction retained retained at 1.3 at In1.3T (PAb T).( bheavy). minerals retained at 0.675 T, it is possible to observe the presence of ilmenite, some zircon (inclusions), monazite, and xenotime. Although the latter is not abundant, it is also an interestingIn PA heavymineral minerals since yttrium retained (Y) at 0.675is an T,REE. itit is According possible to to observe EDX, theits compositionpresence of ilmenite, is 38.52% some O, 37.34%zircon (inclusions), (inclusions),Y, 22.96% P, monazite, monaziteand 1.17% and, and Al. xenotime. Ilmenite xenotime. Although is Althoughthe most the latter abundant the islatter not abundant,mineral is not abundant, in it this is also fraction an it interestingis alsoand anis alteredmineralinteresting into since mineralanatase, yttrium sinceespecially (Y) is yttrium an REE. along (Y) According its is aboundariesn REE. to EDX, According and its compositionfractures to EDX, (Figure its is 38.52% composition 8a). O,Not 37.34% just is 38.52%along Y, 22.96% its O, boundariesP,37.34% and 1.17% Y, 22.96%and Al. fractures Ilmenite P, and but 1.17% is theEDX most Al. results Ilmenite abundant showed is the mineral th mostat PA in abundantilmenite this fraction might mineral and be isinconsidered altered this fraction into an anatase,altered and is ilmeniteespeciallyaltered intosince along anatase, its itsTi boundariescontent especially is higher and along fractures (34.85%) its boundaries (Figure than the8a). andtheoretical Not fractures just alongvalue (Figure its(31.56%) boundaries 8a). [39]. Not Additionally, and just fractures along its thisbutboundar EDXTi increaseies results and is showedfractures observed that but followed PAEDX ilmenite results by mighta showeddecreas be consideredethat in thePA ilmeniteFe anpercentage altered might ilmenite asbe suggestedconsidered since its by an Ti Temple contentaltered (1966)isilmenite higher [40]. since (34.85%) Another its Ti than content fact the about theoreticalis higher PA ilmenite(34.85%) value (31.56%) isthan the the negligible [ 39theoretical]. Additionally, amount value (31.56%)of this Mn Ti increasein [39]. its Additionally,composition. is observed Nevertheless,followedthis Ti increase by a this decrease is elementobserved in thewas followed Fe not percentage quantified by a decrease as by suggested EDX, in thethe by small Fe Temple percentage Mn (1966)peak close as [40 suggested]. to Another 6.0 kEV by fact [41]Temple about can stillPA(1966) ilmenitebe observed [40]. Anotheris the (Figure negligible fact 8a). about Some amount PA Fe remains ilmenite of Mn in in is its the the composition. composition negligible amountNevertheless,of the ilmenite of Mn this alteration, in element its composition. as was can notbe seenquantiﬁedNevertheless, in Figure by EDX,8b.this element the small was Mn not peak quantified close to 6.0by kEVEDX, [ 41the] cansmall still Mn be peak observed close (Figure to 6.0 8kEVa). Some [41] can Fe remainsstill be observed in the composition (Figure 8a). of Some the ilmenite Fe remains alteration, in the composition as can be seen of inthe Figure ilmenite8b. alteration, as can be seen in Figure 8b.

(a)(a) (b)(b)

FigureFigure 8. 8. SEMSEM images images and and EDX EDX results results for for ilmenite ilmenite ( (aa))) and andand details detailsdetails of ofof its itsits alteration alterationalteration ( ((bbb).).). * * Note: Note: values values fromfrom Dana Dana (1974) (1974) [39]. [[39].39].

Chemical analysis was also carried out. The head assay results of the oxides of interest are shown in Table 2. For PA, due to the low content of REEs (CeO2, La2O3, and Nd2O3), thorium (Th),

Minerals 2019, 9, 176 10 of 15

MineralsChemical 2019 analysis was also carried out. The head assay results of the oxides of interest10 of are15 shown in Table2. For PA, due to the low content of REEs (CeO 2, La2O3, and Nd2O3), thorium (Th), and and zirconium (Zr), the chemical analysis by ICP-OES was carried out, showing 603.19 ppm of CeO2, zirconium (Zr), the chemical analysis by ICP-OES was carried out, showing 603.19 ppm of CeO2, 570.91 ppm of La2O3, 450.42 ppm of Nd2O3, 107.51 ppm of ThO2, and 456.77 ppm of ZrO2. 570.91 ppm of La2O3, 450.42 ppm of Nd2O3, 107.51 ppm of ThO2, and 456.77 ppm of ZrO2.

Table 2. Selected major elements of whole rock sample according to X-ray fluorescence spectrometry Table 2. Selected major elements of whole rock sample according to X-ray fluorescence spectrometry (XRF) results. (XRF) results. Sample Fe2O3 (%) TiO2 (%) ZrO2 (%) REE + P2O5 (%) SampleLC Fe1.42 O3 (%)1.5 TiO 2 (%)0.36 ZrO2 (%)<0.1 REE + P2O5 (%) LCLP 2.2 1.42.6 1.51.1 0.360.2 <0.1 LPPA 0.7 2.21.5 2.6<0.1 1.1<0.1 0.2 PA 0.7 1.5 <0.1 <0.1 Note: REE (CeO2, La2O3, Nd2O3 + ThO2). Note: REE (CeO2, La2O3, Nd2O3 + ThO2). Overall, it was possible to observe a significant difference between the Luis Correia samples and theOverall, Prado it sample was possible (Figure to9) observe in terms a of significant in which particledifference size between interval the the Luis oxides Correia of interest samples and (TiOthe Prado2, ZnO2 sample, Fe2O3, (FigureREE oxides9) in, termsand P2 ofO5 in) are which. These particle oxides size are intervalpreferentially the oxides concentrate of interestd at (TiO−150 2, ZnO2, +53 µm for LC (Figure 9a), at −106 +53 µm for LP (Figure 9b), and for PA at −297 +106 µm size Fe2O3, REE oxides, and P2O5) are. These oxides are preferentially concentrated at −150 +53 µm for LC fractions(Figure9 (Figurea), at − 9c106). Specifically +53 µm for about LP (Figure PA REE9b), oxides and + for P2 PAO5, they at − tend297 +106to concentrateµm size fractionsat −297 +150 (Figure 9c). µm, where almost 28.6% of the total mass contained 83.4% of the REE oxides and P2O5. Moreover, in Specifically about PA REE oxides + P2O5, they tend to concentrate at −297 +150 µm, where almost LC, 31.39% P2O5 content is concentrated at −75 +53 µm and for LP this value is 46.57%, in terms of 28.6% of the total mass contained 83.4% of the REE oxides and P O . Moreover, in LC, 31.39% P O mass distribution. 2 5 2 5 content is concentrated at −75 +53 µm and for LP this value is 46.57%, in terms of mass distribution.

(a) (b) (c)

Figure 9. Selected major elements in terms of oxides (ZrO2, Fe2O3, REE+P2O5 and TiO2) of raw Figure 9. Selected major elements in terms of oxides (ZrO2, Fe2O3, REE+P2O5 and TiO2) of raw materialmaterial by by size size fraction fraction of LC of LC(a), (LPa), ( LPb) and (b) andPA (c PA) samples (c) samples,, according according to the XRF to the results. XRF results.

3.2.3.2. Recovery Recovery Test Test of ofBahia Bahia Sample Sample Mass and metallurgical balances of the recovery test are presented in Figure 10 as well as the Mass and metallurgical balances of the recovery test are presented in Figure 10 as well as the particle distribution of the tested sample. The oxides considered for the process control were SiO2 for particle distribution of the tested sample. The oxides considered for the process control were SiO2 for quartz and other light minerals, TiO2 for ilmenite and rutile, ZrO2 for zircon, and P2O5 for monazite. quartz and other light minerals, TiO for ilmenite and rutile, ZrO for zircon, and P O for monazite. The SiO2 present in the zircon structure 2was discounted based on the average2 of the EDX values.2 5 The SiO2 present in the zircon structure was discounted based on the average of the EDX values.

(a)

Figure 10. Cont.

Minerals 2019, 9, 176 11 of 15

Figure 10. Particle size distribution of the PA sample (a) and mass and metallurgical balances (b).

The first gravity separation by shaking table shows values up to 85.0% for metallurgical recoveries of TiO2, ZrO2, and P2O5. The percentage of heavy minerals rises from 3.4% to 28.3%. After the magnetic separation stage, two bulk concentrates are obtained. Zircon is concentrated in the nonmagnetic concentrate, where 93.2% ZrO2 is recovered. However, this fraction was still very contaminated with quartz (96.8% SiO2 content due to quartz and other light minerals). Because of that, an additional shaking table cleaning stage was added in the process, obtaining a final nonmagnetic concentrate with 19.5% heavy minerals. This concentrate has 7.7% ZrO2 with good ZrO2 recovery (71.3%). Presumably, the titanium-bearing minerals such as rutile (Figure5) are also in the nonmagnetic fraction due to its TiO2 content (6.6%). The magnetic concentrate is composed of 50.5% TiO2 and 2.5% P2O5, and for the individualization of ilmenite and monazite, a differential magnetic separation was used, which related the distinct mineral magnetic susceptibilities with the belt speed of the magnetic separator (Figure 11). In this process, 0 rpm is a reference to nonmagnetic minerals still present in the magnetic concentrate (11.1% SiO2 and 0.2% ZrO2). The fractions tested were −270 µm, +212 µm, and −212 µm. The variations of fraction densities according to the belt speed are described in Figure 11a. These values were compared with theoretical densities of ilmenite (4.7 g·cm−3), monazite (5.0 to 5.3 g·cm−3) and quartz (2.65 g·cm−3)[39]. Thus, it is possible to infer that monazite was concentrated at 150 rpm for the −212 µm fraction and at 200 rpm for the +212 µm fraction, whereas ilmenite was recovered at 100, 150, and up to 200 rpm for the +212 µm fraction, and at 150 rpm and up to 200 rpm for the −212 µm fraction. Consequently, the finer material (−212 µm fraction) has more minerals with low magnetic susceptibility, namely monazite, which is in accordance with Figure9. The ilmenite final concentrate is considered that recovered at 250 and 300 rpm, and according to the chemical analysis by XRF (Figure 11b), TiO2 content is slightly higher than 60.0%. This value is consistent with those found for the composition of PA ilmenite, suggesting the presence of altered ilmenite with a lower Fe content and higher Ti content, as verified in the characterization studies (Figure8a). The P 2O5 content reaches values of almost 20.0% at 150 rpm for the −212 µm fraction, while for the same belt speed the content was 10.0% for the coarser fraction (+212 µm) (Figure 11b). Overall, in both size fractions, SiO2 content decline significantly (less than 5.0% in each material recovered from 50 to 300 rpm) and the

MineralsMinerals2019 2019, 9 , 176 1212 ofof 15 15

rpm) and the average ZrO2 content is 0.66% at 0 rpm. This result demonstrated the possibility of averageselective ZrO separation2 content isbetween 0.66% at ilmenite 0 rpm. This and result monazi demonstratedte by varying the possibilitythe belt speed of selective of the separation magnetic betweenseparator. ilmenite and monazite by varying the belt speed of the magnetic separator.

(a) (b) Figure 11. Density variations of the material recovered in different belt speeds (a), and variation of Figure 11. Density variations of the material recovered in different belt speeds (a), and variation of selected oxide (TiO2 and P2O5) contents for +212 µm and −212 µm size fractions according to the selected oxide (TiO2 and P2O5) contents for +212 µm and –212 µm size fractions according to magnetic separator’s belt speeds (b). the magnetic separator’s belt speeds (b). 4. Conclusions 4. Conclusions This study shows a compilation of data of Brazilian heavy mineral sands. The Brazilian deposits of heavyThis minerals study shows have a beencompilation known of since data the of Brazi 1940s,lian with heavy the mineral beginning sands. of monazite The Brazilian concentrate deposits productionof heavy minerals by INB. Some have of been these kn depositsown since are locatedthe 1940s, along with the the southeast beginning Brazilian of monazite coastline, concentrate especially inproduction Rio de Janeiro by andINB. Espirito Some Santoof these Provinces. deposits However, are located they along are not the widely southeast explored, Brazilian being restrictedcoastline, nowadaysespecially toin the Rio Brazilian de Janeiro northern and Espirito region Santo at Guaju Provinces. mine (Cristal However, Group) they in Paraibaare not Province,widely explored, where thebeing reserves restricted may nowadays be exhausted to the within Brazilian a few northern years. Only region one at new Guaju project, mine to(Cristal extract Group) ilmenite in Paraiba in Sao JosProvince,é do Norte, where Rio the Grande reserves do Sulmay Province, be exhausted was found. within a few years. Only one new project, to extract ilmeniteThe otherin Sao question José do isNorte, that theRio constantGrande do reference Sul Province, to heavy was minerals found. such as ilmenite, zircon, and rutileThe as byproducts other question of REE is that deposits the constant gives the reference impression to heavy of a lackminerals of information such as ilmenite, or a consolidated zircon, and databaserutile as inbyproducts their respect. of REE Normally deposits these gives sources the impression are restricted of a lack to private of information companies or a or consolidated dispersed amongdatabase public in their entities. respect. Despite Normally the existence these sources of references are restricted to Brazilian to private resources companies in many or dispersed reports aroundamong thepublic world, entities. investments Despite in the this existence sector are of low. references to Brazilian resources in many reports aroundIn the the two world, studied investments areas (Piaui in this and sector Bahia), are thelow. heavy minerals of interest (ilmenite, monazite, rutile,In and the zircon) two studied wereidentified areas (Piaui by and SEM Bahia), and XRD the analyses.heavy minerals The total of interest heavyminerals (ilmenite, of monazite, the two Piauirutile, samples, and zircon) LC and were LP, identified were 6.45% by andSEM 10.14%, and XRD respectively, analyses. andThe fortotal the heavy Bahia minerals sample, theof the figure two wasPiaui 3.4%. samples, The head LC and assays LP, ofwere the 6.45% main and oxides, 10.14%, by XRF, respectively, showed contents and for the of 1.5%,Bahia 2.6%, sample, and the 1.5% figure of TiOwas2 for3.4%. the The LC, head LP, andassays PA of samples. the main LP oxides, had the by highestXRF, showed content contents of ZrO 2of(1.1%) 1.5%, and2.6%, REEs and (CeO1.5% 2of, LaTiO2O23 ,for Nd the2O 3LC,, and LP, ThO and2), PA and samples. P2O5 (0.2%). LP had For the PA, highest due to thecontent low contentsof ZrO2 (1.1%) of REEs, and thorium REEs (CeO (Th),2, andLa2O zirconium3, Nd2O3, (Zr),and ThO chemical2), and analysis P2O5 (0.2%). by ICP-OES For PA, was duecarried to the low out, contents showing of 603.19 REEs, ppm thorium of CeO (Th),2, 570.91and zirconium ppm of La (Zr),2O3, 450.42chemical ppm analysis of Nd2 byO3 ,ICP-OE 107.51 ppmS was of carried ThO2, andout, 456.77showing ppm 603.19 of ZrO ppm2. However, of CeO2, the570.91 THM ppm of these of La occurrences2O3, 450.42 ppm is still of quite Nd2O low3, 107.51 when comparedppm of ThO with2, and other 456.77 deposits, ppm andof ZrO just2.reinforces However, thethe small THM Brazilian of these participation occurrences in is this still market quite (Figure low when2). Investments compared in with exploration other deposits, works for and heavy just mineralreinforces sands the could small change Brazilian this participation scenario. in this market (Figure 2). Investments in exploration worksThe for recovery heavy mineral test of the sands Bahia could sample, change using this physicalscenario. separation equipment such as a shaking table andThe arecovery magnetic test separator, of the Bahia showed sample, valuable using metallurgical physical separation recoveries equipment at around such or greateras a shaking than 70%table for and each a stagemagnetic (Figure separator, 10), demonstrating showed valuable a reliable metallurgical test execution. recoveries The final at concentratearound or greater of ilmenite than is70% composed for each of upstage to 60.0%(Figure titanium 10), demonstrating dioxide after differentiala reliable magnetictest execution. separation. The final These concentrate concentrates of obtainedilmenite foris composed +212 µm atof 250 up andto 60.0% 350 rpm, titanium and −diox212ideµm after at 300 differential rpm could magnetic even be separation. commercialized These sinceconcentrates their contents obtained satisfy for specifications+212 µm at 250 of and the Brazilian350 rpm, marketand –212 (53% µm TiO at 2300and rpm <0.1% could P2O even5)[42 be]. Thesecommercialized physical methods since their proved contents to be efficient satisfy tospecifications selectively separate of the Brazilian ilmenite frommarket monazite. (53% TiO2 and

Minerals 2019, 9, 176 13 of 15

Author Contributions: C.C.G. performed all characterization analysis and mineral processing tests. P.F.A.B. contributed with the design of the mineral processing. Both C.C.G. and P.F.A.B. authors contributed to the final version of the manuscript. P.F.A.B. supervised the project. Funding: This research received no external funding. Acknowledgments: The authors acknowledge the Center for Mineral Technology (CETEM), which permitted this project development, and also the National Council for Scientific and Technological Development (CNPq) for the research grant; the Mineral Processing Laboratory of the University of São Paulo (LTM) for some tests, and the G-4 Esmeralda company for the PA sample. Conflicts of Interest: The authors declare no conflict of interest.

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