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Bolobov V.I.,National Mineral Resources University | Shneerson Ya.M.,Scientific Research Center Gidrometallurgiya | Lapin A.U.,Scientific Research Center Gidrometallurgiya
Tsvetnye Metally | Year: 2017

The possibility of crevice corrosion of commercial titanium VT1-0 (1-0) and titanium wrought alloy VT14 (14) was analyzed in high temperature leaching of pyrite gold concentrates in laboratory autoclave using gravimetric method. All materials were tested in the form of assemblies consisting of two plates with holes connected together using the fluoroplastic sealing material and fluoroplastic gaskets with the fixed gap of 0.1 mm and 1 mm. There is almost no corrosion on outer and side surfaces of all plates, but a brown, easily removed plaque is in local areas of the internal surfaces. Removal of the plaque found the blackened rough metal surface. If you take the maximum of the obtained values of the mass loss to the area under the metal gasket (where corrosion is fixed), the rate of destruction of titanium and its alloys may be obtained (14.5 and 0.72 mm/year, respectively). Large titanium susceptibility to crevice corrosion in autoclave work products (particularly in chloride-containing mediums) is noted. Crevice corrosion of titanium and its alloys in the products of high-temperature oxidative leaching of gold-bearing sulphide concentrates is connected with decreased concentration of oxidants (Fe3+, O2) in the gap compared with the concentration in the bulk solution and the slow removal of products of corrosion reactions leading to a common activation of the metal surface and to facilitate the anode process of its dissolution.

Zaytsev P.V.,Scientific Research Center Gidrometallurgiya | Shneerson Ya.M.,Scientific Research Center Gidrometallurgiya
Tsvetnye Metally | Year: 2016

Key lines of development of autoclave hydrometallurgy are described, especially low- And high-temperature processes, oxidation catalysts and chloride addition, processes inclusive fine and ultrafine grinding. It is given a brief overview of the autoclave enterprises practice relative to processing of sulphide copper-bearing raw materials. Hydrometallurgical processing methods of sulphide copper-bearing raw materials has been developed since 1970 for a variety of reasons, including ecological regulation. This result into an active development of a liquid-liquid extraction - electroextraction (SX-EW) process with reference to solutions of the secondary sulphides atmospheric leaching. The following was an active application of autoclave processes to chalcopyrite, pyrite and chalcosine leaching. Use of autoclave processes provides high intensity of leaching, selectivity and complete extraction of valuable components into solution. They are easy to integrate into existing hydrometallurgical facilities on oxidized and secondary copper ores processing. Autoclave-hydrometallurgical method allows effectively convert complex raw materials with compound composition into cathode copper as well as marketable products containing nickel, cobalt, metals of platinum group, gold, silver etc. Selection of a specific technology is determined by the complex of conditions, including mineral composition of raw material, geographical location of deposit, remoteness from the main industrial areas, existence of manufacturing facilities, availability of labour resources etc.

Blokhin A.A.,Saint Petersburg State Polytechnic University | Pleshkov M.A.,Scientific Research Center Gidrometallurgiya | Shneerson Ya.M.,Scientific Research Center Gidrometallurgiya | Mikhaylenko M.A.,Representative Office of Purolite Ltd. in Russia
Tsvetnye Metally | Year: 2016

There was carried out the assessment of the results, reached using strongly basic anionites for sodium tungstate conversion into ammonium tungstate during the processing autoclave-soda decomposition solutions of standard sheelite concentrates. Sampling the gel anionites AM, Amberjet 4400, Purolite SGA 600, Purolite PFA600 and macroporous anionite Purolite A500U for tungsten sorption directly from carbonate solutions defined the largest tungsten capacity of gel anionites Purolite PFA600 and Amberjet 4400. Anionites transition from chloride into hydrocarbonate or carbonate forms allows significant increase of their tungsten capacity to the skip and complete dynamic exchange capacity. Anionites transition from hydrocarbonate into carbonate form has almost no influence on their capacity characteristics. There were obtained the data about tungsten desorption from anionites by the mixture of solutions NH4HCO3 and (NH4)2CO3 and ammonia solutions NH4Cl. Application of both methods leads to the similar results. There were carried out the experiments of tungsten sorption from real solutions of autoclave-soda decomposition of sheelite concentrate, containing the impurities of silicon, arsenic, phosphorous, molybdenum and organic substances, together with target component. During the sorption from real solutions, complete dynamic exchange tungsten capacity of anionite Purolite PFA600 and anionite Amberjet 4400 reach 145 mg WO3/ml of ionite and 136 mg WO3/ml of ionite, respectively. Anionite transfer from hydrocarbonate form into carbonate, as well as NaOH addition to the sorption-fed solution leads to reduction of silicon sorption, and to decreasing its concentration in strippants.

Maltseva E.E.,Saint Petersburg State Polytechnic University | Blokhin A.A.,Saint Petersburg State Polytechnic University | Pleshkov M.A.,Scientific Research Center Gidrometallurgiya | Murashkin Yu.V.,Saint Petersburg State Polytechnic University | Mikhaylenko M.A.,Representative Office of Purolite company in CIS
Tsvetnye Metally | Year: 2014

There was researched the possibility of extraction of rhenium from molybdenum-containing solutions after autoclave decomposition of molybdenite concentrates by oxygen in presence of nitric acid, using weak base anion resins Purolite A170 and A172. There was found that rhenium is adsorbed by these resins completely, and rhenium distribution coefficients on them are decreased slightly with increasing of concentration of sulfuric acid. Significant amounts of molybdenum are sorbed by A170 macroporous resin with rhenium, in contrast to A172 gel resin. However, when sulfuric acid concentration is increased from 0.2 to 2 mol/l, molybdenum distribution coefficient on A170 resin is reduced by more than an order of magnitude. When concentration of nitric acid in the solutions is increased, the rhenium capacity of both anion exchange resins is decreased. Rhenium stripping by ammonia solutions from A172 resin is not complete, which leads to reduction of its rhenium sorption value in next sorption-stripping cycles. At the same time, ammonia solutions readily strip rhenium from A170 resin. Usage of A170 macroporous resin as sorbent was offered on the first stage of sorption extraction of rhenium directly from solutions, obtaining as a result of decomposition of molybdenite concentrates. Both A170 macroporous and A172 gel resins are applicable for the second concentration of rhenium from primary desorbates.

Shneerson Ya.M.,Scientific research Center Gidrometallurgiya | Markelov A.V.,Scientific research Center Gidrometallurgiya | Chugaev L.V.,Scientific research Center Gidrometallurgiya | Kabisova A.S.,Scientific research Center Gidrometallurgiya
Tsvetnye Metally | Year: 2015

Great difficulties in modeling of autoclave oxidation processes consist in accurate determination of mineral surface during the process. Currently there are several widely used kinetics models, taking into account the change in the surface of oxidized material, such as shrinking core model or population balance. Each one has its own advantages and disadvantages. In this work, there was used the kinetics function model, developed by E. M. Vikdorchik and A. B. Sheinin in early 1970-s. This model was adapted for high temperature POX process. On the basis of this model, the kinetic parameters for 13 flotation concentrates were calculated for the temperature range of 190-230 °C and oxygen partial pressures of 0,3-0,9 MPa. The concentrates differed by the content of pyrite, arsenopyrite and pyrrhotite. The following kinetics parameters were calculated for each material: kinetic function, reaction order, activation energy. Chemical reaction was the rate-limiting step for all materials. All activation energies were within the range of 40-90 kJ/mole. The reaction order for concentrates with over-representation of pyrite and arsenopyrite ranged from 0,7 to 1. Reaction order for concentrates with over-representation of pyrrhotite ranged from 0,6 to 0,9. Kinetics characteristics and kinetic function can be used for the continuous process modeling. The resulting mathematical model quite accurately describes the results of real pilot plant test, so this model can be used for industrial implementation and industrial autoclave calculations. The gold recovery on cyanidation after POX for all concentrates is more than 94%.

Blokhin A.A.,Saint Petersburg State Polytechnic University | Pleshkov M.A.,Scientific Research Center Gidrometallurgiya | Murashkin Yu.V.,Saint Petersburg State Polytechnic University | Shneerson Ya.M.,Scientific Research Center Gidrometallurgiya
Tsvetnye Metally | Year: 2016

There was made a comparison of efficiency of application of anionites Lewatit MP62 and AM-2b (AM-26) and ampholyte VP-14K (BPpi;-14K) for conversion of sodium tungstate into ammonium tungstate. Tungsten capacity of anionite Lewatit MP62 is closed to ampholite VP-14K and is by ∼1.5 times higher than the one of anionite AM-2b. Tungsten desorption from anionites Lewatit MP62 and AM-2b by ammonia solution at the room temperature is not complete. Increasing of temperature to 52-54 °C makes possible the significant improvement of results of tungsten desorption from both anionites: tungsten desorption completeness is considerably increased; eluent volumes, which should be passed through anionites, are decreased; and tungsten concentration in strippants is increased. Experiments with application of anionite Lewatit MP62 were carried out in dynamic conditions for the processing of sodium tungstate solution, obtained as a result of autoclave-soda leaching of tungsten from scheelite concentrate of one of concentration plants. Initial solution had the following composition, g/l: 62 of WO3, 102 of Na2CO3; 0.23 of Si; 3.36 of organic substances (assessment was carried out by the indicator of chemical oxygen uptake). After hydrolytic purification from silicon, solution was oxidized to the pH = 3.3, separated from the isolated organic substances and directed to the sorption into the column, fulled with anionite. Tungsten desorption was carried out by 14% solution of NH4OH at the temperature of 54 °C. During the sorption of tungsten from the industrial solution, tungsten capacity of anionite MP62 is not less high than during the sorption from model solutions (>300 mg of WO3/ml of anionite). Besides, there is confirmed the complete desorption of tungsten with hot ammonia solutions from anionite MP62. Concentration of WO3 in marketable desorbate was 78 g/l.

Zaytsev P.V.,Scientific Research Center Gidrometallurgiya | Fomenko I.V.,Scientific Research Center Gidrometallurgiya | Chugaev L.V.,Scientific Research Center Gidrometallurgiya | Shneerson Ya.M.,Scientific Research Center Gidrometallurgiya
Tsvetnye Metally | Year: 2015

Pressure oxidation allows to carry out the efficient processing of goldbearing sulfide materials. However, application of this method for processing of double refractory raw materials leads to irreversible gold losses due to autoclave preg-robbing of gold by organic carbon. Thermodynamic and experimental data indicate that almost complete sulfide decomposition leads to a high value of reduction-oxidation potential. At this value, the partially oxidized gold, revealed from sulfides, is further oxidized and dissolved within formation of tetrachloroaurate (III) (even in the presence of small amounts of chloride ion). Gold (in the form of chloride complex) is sorbed by organic carbon and becomes unavailable for subsequent cyanidation. In this paper, there are reviewed the methods, practiced in the gold industry to remove the autoclave preg-robbing. Laboratory studies demonstrate that limestone or lime addition to double refractory concentrate before pressure oxidation lead to decrease of the POX solution acidity. Furthermore, the limestone addition reduces the oxygen partial pressure due to formation and evolution of carbon dioxide to autoclave gaseous phase. These leads to the decrease of redox potential of oxidized slurry thereby reducing the gold solubility, gold preg-robbing by organic carbon under POX conditions, and allows to increase precious metal recovery via cyanidation.

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