United States Patent (19) 11 3,944,414 Yanagida et al. (45) Mar. 16, 1976 54 TREATMENT OF ANODE SLIME FROM 2,048,563 7/1966 Poland................................ 75199 X COPPER ELECTROLYSS 4. 75) Inventors: Tokio Yanagida, Osaka; Ariyoshi Saito, Omiya, Naoyuki Hosoda, Primary Examiner-G. Ozaki Toyonaka, Fukuzo Kaneko, Omiya, Attorney, Agent, or Firm-Robert E. Burns; all of Japan Emmanuel J. Lobato, Bruce L. Adams 73) Assignee: Mitsubishi Kinzoku Kabushiki Kaisha, Japan 22 Filed: Oct. 1, 1974 57 ABSTRACT (21) Appl. No.: 511,475 Process for the flotation of anode slime from copper electrolysis comprising subjecting the anode slime, as 52 U.S. Cl........................ 75/99; 75/83; 7.5/101 R; a preliminary treatment, to attrition treatment in com 75/117; 75/118 R bination with a copper leaching treatment in a me (51) Int. Cl”............................................ C22B 7700 dium of an acid solution. The floated material ob 58 Field of Search........ 75/101 R, 1 17, 118 R, 99, tained from the flotation is continuously subjected to 75/83 three processes of roasting, melting and cupellation in a rotary furnace lined with refractory bricks for recov 56 References Cited ery of good quality silver anode. UNITED STATES PATENTS 2,031,299 2, 1936 Betterton................................ 75/99 9 Claims, 8 Drawing Figures PRESENT INMENTION ANODE SLIME SULFURIC ACO ATTRTION SETLNG WESSEL SLME FREE COP SUFATE OF COPPER SOLUTION - FOAON REAGENTS ALNG FLOATED AERA SAGT SILVERANODE SELENIUM COPPER SMELING OR LEAD SMETING U.S. Patent March 16, 1976 Sheet 1 of 5 3,944,414 ANODE SLIME F G. SULFURIC ACD COPPER LEACHENG COPPERSOLUTION SULFATE '5EFM LOTATION REAGENTS FLOTATION TALING FLOATED MATERIAL F G. 2 ANODE SLIME SULFURIC ACID A TRTO N SETTLNG SLIME FREE COPPER OF COPPER SULFATE SOLUTION FLOTATION REAGENTS FLOTATION TALING FLOATED MATERIAL U.S. Patent March 16, 1976 Sheet 2 of 5 3,944,414 F G. 3 ANODE SLIME SULFURIC ACD COPPER LEACHING FILTERING COPPERSOLUTION SULFATE SLIME FREE OF COPPE R (WATER WASH) ATTRITION FLOTATION REAGENTS FLOTATION TALING FLOATED MATERIAL F G. 5 U.S. Patent March 16, 1976 Sheet 3 of 5 3,944,414 F G. 4 (A) PRIOR ART ANODE SLIME SULFURIC ACID COPPER LEACHING FILTERING COPPER SULFATE SL SOLUTION OF REDUCNG AGENTS FLUXES COPPER SMELTIN OR LEAD SMELTING CUPELLATION FURNACE LTHARGE U.S. Patent March 16, 1976 Sheet 4 of 5 3,944,414 F G. 4 (B) PRESENT INVENTION ANODE SLIME SULFURIC ACID ATTRTION SETTLNG VESSEL SLIME FREE COPPER SULFATE OF COPPER SOLUTION FLOTATION REAGENTS FLOTATION TALNG FLOATED MATERIAL ROTARY FURNACE SLAGT SILVERANODE SELENIUM COPPER SMELTNG OR LEAD SMELTING U.S. Patent March 16, 1976 Sheet 5 of 5 3,944,414 3,944,414 1 2 sents the silver selenide and gold telluride, while the TREATMENT OF ANODE SLIME FROM (COPPER gray-blackportion wrapped by the white portion repre ELECTROLYSES sents the lead sulfate. We have made various studies to develop a method BACKGROUND OF THE INVENTION to separate the wrapped lead sulfate from the outer The present invention relates to an improved process layer consisting of the silver selenide and gold telluride, for treating anode slime from copper electrolysis. and, as a result, have arrived at a conclusion that fric In the electrolysis of crude or blister copper for ob tional and abrasive action by attrition is especially use taining electrolytic copper, the byproduct anode slime ful for this purpose. resulting therefrom contains valuable metals such as 10 gold, silver, copper, lead, selenium, and the like. The SUMMARY OF THE INVENTION recovery of these valuable metals by treating such It is an object of the present invention to provide a anode slime is of great importance in a copper refinery process for the flotation of anode slime from copper process. electrolysis which comprises subjecting the anode slime Methods of treating the anode slime to recover the 15 to the frictional and abrasive action by attrition in com valuable metals contained therein which have been bination with a copper leaching treatment in a medium heretofore proposed comprise extremely complicated of an acid solution to remove an outer layer consisting processes wherein these valuable metals are extracted of silver selenide and gold telluride in the slime parti one by one and gold and silver are finally recovered, cles and thereafter subjecting the attrition treated slime although these methods may be somewhat modified 20 to flotation to ensure a complete separation of lead depending upon the composition of the anode slime. from the slime. The main factor making the recovery process compli It is another object of the present invention to pro cated is, interalia, the presence of lead which is usually vide a method of treating the floated material of ex contained in an amount of about 10 to 30 % in the tremely low lead content resulting from the flotation. anode slime. For example, in the roasting process for 25 The nature, further features, and utility of this inven recovering selenium, the presence of lead may reduce tion will be more clearly apparent from the following volatilization of the selenium. Also, in recovering gold detailed description, beginning with a consideration of and silver, some of the reduced lead must be re-oxi general aspects of the invention and concluding with dized and separated in the subsequent cupellation pro specific examples of practice illustrating preferred em cess. Such repeated oxidation and reduction of the lead 30 yields a large amount of semiprocessed products such bodiments of the invention, when read in conjunction as fume ash and litharge composed mainly of lead with the accompanying illustrations briefly described which tend to contribute to complication of the recov below. ery process. BRIEF DESCRIPTION OF THE ILLUSTRATIONS Various methods have been hitherto proposed to 35 simplify these complicated treatment processes and to In the illustrations: recover the aforementioned valuable metals more eco FIG. 1 is a system diagram indicating one example of nomically and advantageously. These methods include a prior art flotation of anode slime from copper elec subjecting the anode slime to flotation to remove sub trolysis; stantial amounts of the lead contained therein before 40 FIG. 2 is a system diagram indicating one example of entering into the actual recovery process. For example, the present invention wherein a copper leaching treat one of these methods comprises oxidizing a suspension ment of anode slime from copper electrolysis and an of the anode slime in a sulfuric acid solution (about attrition treatment thereof are simultaneously carried 200g/l) at a temperature above 70°C by passing air out; therethrough while it is being stirred in order to leach 45 FIG. 3 is a system diagram indicating another exam copper therefrom and subjecting the remaining anode ple of the present invention wherein an attrition treat slime to a flotation treatment, as is illustrated in FIG. 1. ment is carried out subsequently to a copper leaching However, these methods are disadvantageous in that treatment, the net yields of gold, silver, selenium and the like FIGS. 4(A) and 4(B) are system diagrams respec carried into the floated material is as low as 85 to 95%, 50 tively indicating one example of the process of treating and the separation of lead as tailings, which are their anode slime according to one process of the prior art main objects, are unsatisfactory, whereby, they have and one example of the process of treating anode slime not yet been put into practice. according to this invention; Since the anode slime usually is in the form of fine FIG. 5 is an elevation, with a part cut away, showing particles having a particle size not greater than 50p, the 55 a tower mill; and slime has been subjected to a copper leaching treat FIGS. 6 and 7 are photomicrographs respectively ment or a flotation treatment without having under showing the states of anode slime which has undergone gone any mechanical treatment such as grinding and no attrition treatment and anode slime which has un crushing in the conventional methods. We have exam dergone an attrition treatment respectively. ined sections of anode slime particles under a micro 60 scope and found that the anode slime particles are DETAILED DESCRIPTION composed of aggregates each made up of finer particles In the process of the present invention, the attrition as is shown in the photomicrograph of FIG. 6, and each treatment may be carried out simultaneously with the finer particle is composed of an outer layer comprising copper leaching treatment of the anode slime in a me silver selenide and gold telluride and a core comprising 65 dium of an acid solution or may be conducted subse lead in the form of lead sulfate. In other words, the lead quently to the copper leaching treatment. The flow is present as lead sulfate which is wrapped by the outer sheets of these two processes are shown in FIGS. 2 and layer. In the photomicrograph, the white portion repre 3. 3,944,414 3 4 In FIG. 7, a microphotograph illustrating the state of dery form, and the volatilization rate of the selenium is the anode slime rubbed and abraded by the attrition increased to 2 times that in the conventional method, treatment is shown. In the microphotograph, the white whereby the time required for the oxidizing roasting portion indicates silver selenide or gold telluride. Vi can be greatly reduced. sual examination of this microphotograph reveals that When the volatilization of the selenium is completed, when the anode slime particles are subjected to the the roasted sline is then melted. Since the roasted attrition treatment, the outer layer thereof comprising slime contains little lead and other gangues as a result silver selenide and gold telluride is gradually rubbed off of the flotation treatment, there is no need to add re because of the frictional and abrasion action.