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Investigation on a Novel Galena Depressant in the Flotation Separation from Molybdenite

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Investigation on a Novel Galena Depressant in the Flotation Separation from Molybdenite minerals Article Investigation on a Novel Galena Depressant in the Flotation Separation from Molybdenite Yangjia Hu 1, Zhiqiang Zhao 1,2, Liang Lu 1,3,4 , Huanyu Zhu 5, Wei Xiong 1,3,4, Yangge Zhu 1,3,4, Sigang Luo 1, Xingrong Zhang 1,3,4,* and Bingqiao Yang 5,* 1 State Key Laboratory of Mineral Processing, BGRIMM Technology Group, Beijing 102600, China; [email protected] (Y.H.); [email protected] (Z.Z.); [email protected] (L.L.); [email protected] (W.X.); [email protected] (Y.Z.); [email protected] (S.L.) 2 Civil and Resource Engineering School, University of Science and Technology Beijing, Beijing 100083, China 3 China-South Africa Joint Research Center on the Development and Utilization of Mineral Resources, Beijing 102628, China 4 China-South Africa Belt and Road Joint Laboratory on Sustainable Exploration and Utilization of Mineral Resources, Beijing 102628, China 5 School of Resources and Safety Engineering, Wuhan Institute of Technology, Wuhan 430073, China; [email protected] * Correspondence: [email protected] (X.Z.); [email protected] (B.Y.) Abstract: In this study, a novel organic depressant maleyl 5-amino-1,3,4-thiadiazole-2-thiol (MATT) was synthesized and utilized as a galena depressant in the flotation separation of molybdenite and galena. The results of the flotation test indicated that MATT exhibited an excellent depression ability on galena but barely influenced the flotation of molybdenite in the pH range of 6.0–11.0. Zeta potential results suggested that MATT preferentially adsorbed on galena surface. UV-visible spectroscopy analysis indicated that the stoichiometric ratio of lead ion and reagent in the complex Citation: Hu, Y.; Zhao, Z.; Lu, L.; compound. XPS analysis demonstrated that the S (-SH) atom and N (1,3,4-thiadiazole group) atom of Zhu, H.; Xiong, W.; Zhu, Y.; Luo, S.; MATT coordinated with the Pb atom on galena surface. Zhang, X.; Yang, B. Investigation on a Novel Galena Depressant in the Keywords: flotation; galena; molybdenite; depressant; MATT Flotation Separation from Molybdenite. Minerals 2021, 11, 410. https://doi.org/10.3390/min11040410 1. Introduction Academic Editor: Cyril O’Connor Molybdenum plays a vital role in steel, petroleum and chemical industries due to its excellent physical-chemical properties and mechanical performances [1]. Mo metal is Received: 4 March 2021 mainly extracted from molybdenite, which is generally associated commonly with other Accepted: 10 April 2021 Published: 13 April 2021 sulfide ores like chalcopyrite, pyrite and galena [2–4] etc. Since the floatability of these minerals is very similar, it is difficult to obtain molybdenite of a high grade and few Publisher’s Note: MDPI stays neutral impurities. Especially, the presence of lead impurities in molybdenite concentrate not only with regard to jurisdictional claims in degrades the quality of Mo metals, but also causes serious environmental contamination published maps and institutional affil- during the processing of Mo ores [5,6]. Generally, the content of lead in molybdenite iations. concentrate is limited to be less than 0.05% [7]. Therefore, the removal of galena impurity from molybdenite is critical for the production of Mo metals of a high quality. Froth flotation, as a physicochemical separation technique, is an efficient and environm- entally-friendly approach to separate galena from molybdenite, based on the difference in surface properties [8,9]. In most cases, bulk flotation is adopted to recover molybdenite Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. and galena from Mo-Pb raw ores, then molybdenite and galena is separated by preferential This article is an open access article flotation [10]. It has been noted that both molybdenite and galena have a good floatability distributed under the terms and in the presence of a collector (non-polar oil or xanthate) or a frother (Z-200 or pine oil) [11]. conditions of the Creative Commons Therefore, it is hard to separate galena from molybdenite efficiently without any depres- Attribution (CC BY) license (https:// sant. At present, inorganic depressants have a wide application in industrial production, creativecommons.org/licenses/by/ such as potassium dichromate, sulfite and sodium hydrosulfide [12–16]. Although these 4.0/). depressants mentioned above could selectively separate galena from molybdenite, these Minerals 2021, 11, 410. https://doi.org/10.3390/min11040410 https://www.mdpi.com/journal/minerals Minerals 2021, 11, x FOR PEER REVIEW 2 of 13 production, such as potassium dichromate, sulfite and sodium hydrosulfide [12–16]. Alt- hough these depressants mentioned above could selectively separate galena from molyb- Minerals 2021, 11, 410 2 of 12 denite, these inorganic ones suffer from many disadvantages, which are highly toxic and could cause damage to human health. In view of these disadvantages, many researchers have turned to research into some organicinorganic depressants. ones suffer It fromhas been many reported disadvantages, that L-cysteine which [17] are could highly selectively toxic and depress could cause the flotationdamage of to humangalena health.in Pb-Mo flotation. The results showed that the thiol and primary amineIn groups view ofof theseL-cysteine disadvantages, could coordinate many researcherslead sites on have galena turned surface to research. Similarly, into Zhang some etorganic al. [18] depressants. found that poly(acrylamide It has been reported-allylthiourea) that L-cysteine (PAM- [ATU)17] could could selectively separate depressgalena fromthe flotationartificially of mixed galena minerals in Pb-Mo successfully flotation. at The pH resultsaround showed10.5. Acetic that acid the-[(hydrazinyl- thiol and pri- thioxomethyl)thio]mary amine groups-sodium of L-cysteine (AHS) was could synthesized coordinate and lead applied sites in on the galena flotation surface. of galena Simi- andlarly, molybdenite Zhang et al. [7]. [18 It] was found found that that poly(acrylamide-allylthiourea) AHS chemisorbed on galena (PAM-ATU) surface to form could a five sep- numberarate galena ring with from lead artificially atoms on mixed a galena minerals surface. successfully at pH around 10.5. Acetic acid-[(hydrazinylthioxomethyl)thio]-sodiumAlthough a lot of efforts have been made (AHS)to exploit was eco synthesized-friendly and and high applied-selective in the depressantflotation of of galena galena, and it is molybdenite still a difficult [7 ].task It wasto explore found novel that AHS reagents chemisorbed to substitute on galenatradi- tionalsurface galena to form depressants. a five number In this ring work, with a novel lead atoms depressant on a galena named surface. MATT was synthesized and appliedAlthough in athe lot separation of efforts have of molybdenite been made to and exploit galena eco-friendly in various and conditions high-selective (dies de-el pressant of galena, it is still a difficult task to explore novel reagents to substitute traditional dosage, MATT dosage, and pH). Besides, its adsorption mechanism was studied through galena depressants. In this work, a novel depressant named MATT was synthesized and zeta potential, UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS) anal- applied in the separation of molybdenite and galena in various conditions (diesel dosage, ysis. MATT dosage, and pH). Besides, its adsorption mechanism was studied through zeta potential, UV-Visible spectroscopy and X-ray photoelectron spectroscopy (XPS) analysis. 2. Materials and Methods 2.1.2. MaterialsMinerals and and Reagents Methods 2.1.Pure Minerals galena and and Reagents molybdenite minerals were collected from Guangdong Province, China.Pure The galenaores were and first molybdenite selected mineralsby hand werecarefully, collected and then from crushed, Guangdong ground Province, and sievedChina. to The obtain ores various were first size selected fractions. by hand The fractions carefully, containing and then crushed, 38~74 μm ground particles and sievedwere collectedto obtain for various flotation size exper fractions.iments The and fractions the others containing less than 38~74 5 μmµm particlesfor analysis were tests. collected The XRDfor flotation spectra experimentsof galena and and molybdenite the others less was than presented 5 µm for in analysis the Figure tests. 1. The The XRD results spectra of chemicalof galena analysis and molybdenite and XRD show was presented that the purities in the Figure of MoS1.2 The and results PbS are of more chemical than analysis95%. and XRD show that the purities of MoS2 and PbS are more than 95%. a b Galena Molybdenite Intensity Intensity 10 20 30 40 50 60 70 80 10 20 30 40 50 60 70 80 2-Theta (°) 2-Theta (°) Figure 1. XRD spectra of (a) galena and (b) molybdenite sample. FigureSodium 1. XRD spectra hydroxide of (a) (NaOH),galena and hydrochloric (b) molybdenite acid sample. (HCl) and potassium nitrate (KNO3) purchased from Aladdin Chemical Reagent Co., Ltd. (Shanghai, China) were used in the experiments.Sodium hydroxide Diesel was (NaOH), obtained hydrochloric from Guangfu acid Chemical (HCl) Co.,and Ltd.potassium (Hengshui, nitrate China) (KNO and3) purchasedused as the from collector. Aladdin Diesel Chemical was added Reagent in the Co., form Ltd of. ( emulsification,Shanghai, China which) were was used prepared in the experiments.by a Cole Parmer Diesel ultrasonic was obtained processor from (750Guangfu W and Chemical 20 kHz) Co., at 60% Ltd. amplitude (Hengshui for, China 5 min.) andMethyl used isobutylas the collector. carbinol Diesel (MIBC) was purchased
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