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By P. Prusti

An air dense medium fluidised bed separator (ADMFBS) is the efficient process for dry beneficiation of coal. Magnetite powder is used as medium to make required pseudo-fluid density in the fluidised bed. The dynamics behavior of coal particle with reference to its position changes from ideal solution to pseudo-fluid condition in different bed densities depending on its shape, size and density. In this study, three set of projected areas of coal particles were taken. Each set contains four different shapes i.e., cubical, rectangular prism, spherical and triangular prism with different density starting from 1.3 to 1.8 gm/cc. It is observed that coal particles having density less than the bed density, floats in different positions in the dense medium fluidised bed. Higher projected area particles float in deeper height in comparison with smaller projected area. The difference in position of coal particles in the bed increases (nearly 1 to 4 cm) as the coal density approaches towards bed density irrespective of the different shapes. Different shapes of coal particles behave in different ways based on the operating parameters like bed density, coal density and projected area of coal particle. Empirical model equations are proposed to predict the position of coal particle of each shape in the air dense medium fluidised bed system. Keywords: ADMFBS, particle dynamics, projected area, shape

Sep 1, 2012

By T. C. Sun

Two wasted activated sludges (WAS), from an industrial wastewater treatment and a sewage treatment plant respectively, and 7 collectors are used to investigate the feasibility of air flotation thickening of WAS by adding the collectors used in mineral processing. The collectors experimented include straight chain fat acids with different chain length, sodium oleate, alkyl sodium sulphonate, sodium dedecylsulfonate, and dodecylamine. The results show that the thickening efficiency varied depending on different collectors. Of the collectors experimented, dodecanoic acid and dodecylamine are best collector for thickening both sludges.

Jan 1, 2014

By T. Tumidajski

The purpose of the separation processes in coal processing is obtaining products of certain ash contents. In the most of cases it is assumed that the separation process is described by one, selected parameter, which usually is grain size or material density. The separation may be described by means of statistical distributions of random variables, what allows forecasting the separation results of certain enrichment method. There are very well known the applications of approximations of Tromp separation curves or distribution functions of Erasmus, Meloy or Weibull. It is necessary to say that if the fitness of the approximation more suitable, then the characteristics of the process itself is also better. In purpose of obtaining more appropriate results, these methods were modified by application the mathematical functions, as i.e. hyperbolic tangens function. Furthermore, on the basis of empirical data, so-called interpolations may be performed in purpose of getting more appropriate results of approximation. One of the most known techniques of interpolation is Hughes method. This method for interpolating standard data involves breaking down each interval into a number of smaller sub-intervals. The results of such one-dimensional approach not always contain the full in-formation of the searched distribution. It happens because such interpretation of the problem is not completely correct. In practice, the separation process depends not only on the one parameter (i.e. grain size), but also on many other features characterizing certain material (i.e. its density). It seems then that in some cases the application of multidimensional grain characteristics distributions will be more appropriate. In this paper, the technique of joining the distributions of grain size and density by means of so-called Morgenstern distributions is shown. The general form of these distributions is as following:

Jan 1, 2014

By X. Q. Cao

As the second largest phosphate resource in the world, Chinese phosphate ores generally grades with low of P2O5. The presentation of beneficiation test on the low grade of phosphate rock in this paper may be used for a reference for development and utilization of the similar reserves. The ore is a marine sedimentary phosphate rock containing low grade of P2O5 and high content of MgO and R2O3; The banded structure shows its suitability for heavy medium separation. The laboratory heavy liquid testing results indicate that as specific gravity of the heavy liquid is 2.85 g/cm3, a rougher concentrate assaying 28.71% P2O5 could be obtained while the rougher tailings contain only 4.47% P2O5. When the combined process with heavy liquid separation followed by direct & re-verse flotation is employed to treat the feed containing 21.15% P2O5, 3.79% MgO, 1.86% Fe2O3, 3.66% Al2O3, 23.75% A.I, and specific gravity of heavy liquid is 2.84 g/cm3, the optimum mesh of grind is 67.5% minus 200 mesh, a phosphate concentrate contained 32.51% P2O5, 0.48% MgO, 0.81% Fe2O3, 1.69% Al2O3 can be produced at a yield of 55.24%. The concentrate P2O5 recovery is 85% with which quality comply with the Class A specifications for production of phosphate fertilizer.

Jan 1, 2014

By P. Bevilacqua

In this paper the possibility to complete the copper recovery and to enrich in PVC a mixture of plastic granules obtained by grinding electrical cables are investigated. The recovery of a large part of the copper still present among the plastic granules was possible by means of a mechanical screening, the finer polymeric fraction was collected, at the same time. In order to complete the copper polymer separation the following techniques were employed. Counter current separation in water, static dense medium separation with zinc chloride solution and copper extraction with nitric acid and subsequent electrolytic deposition. A Tri-Flo® dynamic dense medium separator was employed in order to separate the lighter polymeric fraction, from the heavier polymeric fraction, mainly PVC. Water or a salt-water solution was employed to feed the separator device.

Jan 1, 2014

By Ye Junjian

The feed ore is the concentrate of low intensity magnetic separation of pyrite tailings, containing TFe47.47%, S19.41% and SiOpyrrhotite. The exploratory tests showed that using a process of flotation followed by magnetic separation could respectively obtain a sulphur concentrate of S 31.08% with a recovery of 82.89%, and an iron concentrate of TFe 59.97% and S 9.52%with a recovery of 30.93%. The reason of iron concentrates with high sulphur grade was that the sulphur grade of flotation tailings was 7.03%. So enhanced flotation for pyrrhotite was investigated in this research. Results show that when the natural pH of ore pulp varied from 5.5 to 6.0, a reagent combination of FS, LH, and BJ displayed the optimum flotation performance for pyrrhotite. After comparisons made on different flotation processing, the previous flotation flow of ?one roughing, one cleaning, one scavenging system and middling reprocessing?, was found, among others, to have the best flotation effect, as the grade and recovery of sulphur concentrate were 31.08% and 82.89%, respectively, and sulphur content of the flotation tailings was 7.03%. The above results indicated it was difficult to raise further the effect of flotation desulphurization. The authors therefore suggested that oxidizing roast should be adopted following the magnetic process for the purpose of further desulphurization. Besides, flue gas containing SO2 8.25%. And the valuable minerals are magnetite and 2 generated from roasting could be reused for sulphuric acid production. Keywords: pyrrhotite, enhanced flotation, desulphurization

Sep 1, 2012

By Liu Xinghua

Yuanjiacun iron ore located in Shanxi province of China has finely disseminated grain size and contains refractory iron-bearing silicate gangue minerals such as chlorite. Therefore, a large amount of secondary slime (the content of -10µm fraction was up to 32.92%) was produced inevitably in fine grinding process, and chlorite was also enriched in concentrate from the content of 4.3% to 14.8% after high intensity magnetic separation. These two characteristics result in the difficulty to deal with Yuanjiacun iron ore by flotation. In this test work, contrast tests between single reverse flotation and selective flocculation desliming-reverse flotation were conducted on Yuanjiacun iron ore. The test results show that after selective flocculation desliming, the iron grade of cationic reverse flotation concentrate increases by 6.15% and the recovery increases by 7.25%; the iron grade of anionic reverse flotation concentrate also increases by 2.15%. Furthermore, analyses of grain size composition and mineral composition were carried out on separation products, the results indicate that selective flocculation desliming plays a dual role of optimizing grain size composition of flotation feed and removing iron-bearing silicate gangue minerals (chlorite) effectively.

Sep 1, 2012

By E. Hulthén

Cone crushers are used in the mineral, mining, and aggregate industry for fragmentation of rock materials. Control systems for cone crusher settings are widely used to compensate for wear and to protect the machines. The eccentric speed in a cone crusher affects the number of compressions the material is exposed to and thus the particle size distribution of the product. Eccentric speed also affects crusher capacity. However, the speed of the crusher is mostly fixed, because speed changes must be made by shifting pulleys, a process which is quite time-consuming. By applying a frequency converter, which has decreased in cost during recent years, it has become possible to adjust the speed continuously. By also applying mass-flow sensors to the process, the crusher can be run optimally to yield the most sellable products in a given moment. Existing systems normally only protect the machine. The sensors can be mass-flow meters, e.g., conveyor-belt scales. To analyze data from the process and calculate the appropriate value for the speed, an algorithm has been developed. The developed algorithm was tested and evolved at a crushing plant for aggregates that produces around 350 kton a year. The algorithm was implemented in a computer that could communicate with the frequency controller, retrieve data from four mass-flow meters, and also interact with the opera-tor. The computer was reachable over the Internet for the researchers at Chalmers and the algorithm was tuned and improved on-line. The result is a crushing stage that consistently and maximally produces the most desirable product. The performance (yield of required products) increased by 4%. As a bonus, the lifetime of the mantles increased 27% on the evaluated crusher.

Jan 1, 2014

By Y. G. Sun

This paper mainly reported separation manganese silver oxidized ores process by amylum de-gradation reduction and its influencing factors. When dosage is given according to nMn : nH2SO4 : n(C6H10O5)n : nH2O=1:k21.8: k116.66:30, the amount of up to 95.93% Mn leach rate and less than 2% silver loss can be obtained. Cyanidation process was used to extracted silver from leaching Mn residues. Silver leach rate could reach 94.15% at consumed amount of 1kg/t NaCN for 1h. Silver leach recovery rate was more than 92.27% by leaching Mn and cyanidation two-step processes so manganese and silver were separated effectively.

Jan 1, 2014

By Dmitriy Makarov

The paper presents the modeling and analysis of oxidation of pyrite copper-zinc ore samples from the Letnee, Yaman-Kasy and Valentorskoye deposits. It is found, that the oxidized samples contain copper and zinc sulfates that are leached under the sample and water contact. It is shown, that sulfide floatability is decreased by the longer-term oxidation.We advise to improve nonferrous metals recovery by joint leaching and ultrasonic treatment of oxidized compounds. Study of the geotechnological processes of non-ferrous metal extraction, on the basis of two copper-zinc ore deposits shows, that heap leaching is of little use for the ores of the Letnee deposit. Leaching results for the Yaman-Kasy ore showed more promise.

Sep 1, 2012

By G. X. Du

Improving reaction effectiveness of asbestos tailings and acid is main means to increase the productivity of magnesium hydroxide and amorphous silica and to reduce production costs. In this paper, the process optimization of acid-leaching reaction process of asbestos tailings is reported. Through the orthogonal experiments of four influence factors, such as acid consumption, reaction temperature, reaction time and initial acid concentration in the leaching reaction. The experiment results indicated that the optimal process parameters were as follows: reaction temperature was 95?, reaction time was 1.5h, acid consumption was 218.9g hydrochloric acid(37%) per 100g asbestos tailings and initial acid concentration was about 25%. The influence significance sequence of the four factors was as follows: reaction temperature > reaction time > mass concentration of hydrochloric acid > hydrochloric acid consumption. Under the optimum process conditions, the leaching rate of MgO was 97.3%, total iron 98.15% and Al2O3 57.9%.

Jan 1, 2014

By Q. J. Liu

The flotation circuit and the reagents of the all-sliming flotation about low grade and hard operation on zinc oxide ore are researched in the paper. The results indicated that there are many types of zinc minerals in this ore, and the composition is very complex. They include hemimorphite, smithsonite, hydrozincite and so on. The ore is seriously sliming. In light of the ore properties, three kinds of flowsheets have tested. They are gravity concentration (cleaning tables), flotation, combined process of gravity concentration and flotation. The test showed that the recovery of zinc is only 17.08% in the gravity separation. In combined process of gravity separation and flotation, the recovery of zinc concentrate is close to 70%. But the flow-sheet is complex and hard to control in the production. The floatation circuit is feasible. In the test, it pay attention to investigate the new combined reagent which is used in selective all?sliming flotation process. The effects of slime are eliminated by the multi-loop treatment of middling. In flotation, the final recovery of concentrate is 88.76%; the grade is 29.50%. The recovery of physical ore is 93%; and the recovery of -10mm fraction is more than 65%.

Jan 1, 2014

The energy dispersion X-ray fluorescence (EDXRF) analysis technique is a rapid and accurate method for describing sample?s element component and percentage composition. On the base of profound research for the national and international development and research condition, the author researched the EDXRF analyze technique and the EDXRF analyzer?s principle in depth, the difficulties and the key points for research and development of EDXRF analyzer; gave a scheme for re-search of bench EDXRF analyzer; researched some algorithms used in energy spectrum analysis; developed the energy spectrum analysis software based on the Visual C++ 6.0; together with the energy spectrum analysis software, the author designed and processed the structural of the bench XRF analyzer and integrated the import X-ray tube, thermoelectrically cooled Si-PIN photodiode X-ray detector and pulse amplitude analyzer as a model machine. The result shows: The model machine can be used in multi-element analysis at the same time for different types of dry mineral samples, with fast analysis speed, accurate model and high stability.

Jan 1, 2014

By Y. Q. Yang

Jig is a kind of conventional and old gravity concentration equipment, which is mainly used in the preconcentration of medium particle fractions of low-grade nonferrous metal ore. In the past ten years, studies on jigs have made a great progress on separation of coarse and fine particle fractions. At the same time, pneumatic jigs have been widely used in processing of nonferrous metal ore. In this paper, pilot test study and commercial operation for several kinds of jigs used in Dachang con-centrator has been introduced. Dachang mining area of GuangXi province is rich in mineral resources, where many minerals exhibit various complex properties. Many elements such as Sn, Pb, Sb, Zn, S, As, Cu, In, Ag, Gd, Ag, Ga, etc, were found in the run-of-mine ore (ROM). At present, Dachang concentrator produces tin concentrate, lead-antimony concentrate and zinc concentrate. Other valuable elements get enriched and recovered in above concentrates. Dachang Mine with a mining operation history more than sixty years will end its mission on the rich ore resource exploitation. At present, low grade ores are porcessed in the concentrator, and the concentrator begins to run at a loss upon processing the low-grade and refractory ore. Heavy medium cyclones were used in the concentrator for processing 20-4mm fraction, Gongge jigs for 4-2mm fraction, and cone concentrator combined with spiral concentrator to discard the tailings of -2mm fractions. In order to minimize overgrinding, table flotation was used to recover some liberated cassiterites in a complex processing technology. Therefore, the concentrator is difficult to manage. Many years studies have shown that heavy medium cyclones and spiral concentra-tors can be replaced by sawtooth shaped wave jigs to discard 50% tailings to improve the grade of feed. And the feed was divided into rich one and poor one to minimize overgrinding of valuable cassiterites with different grinding mills. In this case, the recovery of the valuable minerals can get improved and the flowsheet was simplified. Moreover, the concentrator begins to make profit with reduction of cost. At the same time, pollution in the concentrator gets reduced and the working condition gets improved too. Sawtooth shaped wave jig was used in Changpo concentrator for replacement of cone separators and spiral concentrators to discard the tailings of -4mm fraction, and the yield of discarded tailings got improved from 30% to 50%. Grades of tin, lead and zinc in the tailings are lowered from 0.15%, 0.12%, 0.7% to 0.06%, 0.05%, 0.4% respectively, with a loss reduction of tin, lead and zinc from11%, 9%, 10% to 7.5%, 6%, 5% respectively, corresponding to the increasement of recovery of tin, lead, zinc from 52%, 50%, 55% to 56%, 56%, 62% respectively. Cost of the concentrator for processing one-ton ROM was therefore dropped from RMB155.28 to RMB119.74. Changpo concentrator lost RMB2.5 million in 2003, but it made a profit of RMB0.92 million in 2006 after the innovations. Batac jig was used in Tongkeng concentrator to discard the coarse tailings at 20-4mm, with a discarded yield of 35%, and the grades of valuable minerals got improved with a recovery above 95% for tin, lead-antimony and zinc.

Jan 1, 2014

By H. C. E. Regidor, M. G. Mena, H. D. Mendoza

Cyanidation leaching has always been the most widely used method of extraction of gold in the world. Its low cost and high selectivity has made it the prevalent choice for mining companies, and even for the small scale miners. The use of cyanidation in small scale mining has been an issue for the longest time, mainly due to the operation’s lack of safety measures, health care or environmental protection regulations. In pursuit of more environmentally friendly methods of extraction of gold, several alternative extraction processes have been explored, one of which is chlorination. The chlorination process is advantageous when recovering refractory gold locked in sulfides, as it simultaneously oxidizes the surrounding sulfides as well as dissolve any gold exposed to the lixiviant. This research was conducted to study and develop a safer alternative way of extraction of gold from small scale mining operations, without compromising the recovery of gold. In this study, a variation of the chlorination process has been employed for a refractory flotation concentrate wherein the majority of the gold is locked in sulfides. Hypochlorite-bearing reagents were used as the leaching reagents, and the method developed was a 2-stage leaching process in differing pH conditions. The solution pH and Eh was monitored all throughout the runs, and aliquot samples were taken at time intervals for analysis. SEM-EDS imaging was used to determine the mode of oxidation of the chlorination process, and the image obtained showed that the oxidized layer followed the shape of the particle, suggesting a diffusion controlled process. XRD analysis of the sample before and halfway through leaching further confirmed the oxidation of the sulfides. The amount of gold dissolved in the aqueous solution and in the solid residue were used as the basis for the determination of the recovery of gold. An average gold recovery of up to 84.38% was obtained using the developed method in just 7 hours of leaching. This method was then employed for a pilot-plant scale test and a gold recovery of 79.2% was obtained.

Jan 1, 2018

By Shugang Hu

According to XRD, DTA and SEM detections, the hydration products of blast furnace slag (BFS) based cementing material SL, SLG. were studied in different age periods. The XRD analysis of cementing material SL hydration products showed that the composition of hydration products were mainly amorphous substances, few crystalline substances. Characteristic peak of ettringite hadn?t been found in the spectral line of DTA, and it hadn?t been found in the figures of SEM, either, which was accordant with the conclusion that the cementing performance of SL mainly coming from gel of hydrated calcium silicate (CSH) and hydrated calcium aluminate. However, the main hydration products of SLG are Aft, CSH, and AFm, which are similar to Portland cement. All results suggest that BFS is a suitable base material for cementation. Keywords: blast furnace slag, backfilling cementing material, hydration products, cementing performance

Sep 1, 2012

By V. I. Ryaboy, V. P. Kretov, S. E. Levkovets, I. V. Ryaboy

"Using the flotation of a gold-containing ore from a deposit in Kazakhstan as an example, we have conducted a study designing dialkyldithiophosphate collectors, in addition to xanthates, for the flotation of hard-toenrich gold-containing ores to increase gold recovery.The increased flotational ability of the dialkyldithiophosphates was determined by their surface activity at the liquid-gas interface and their hydrophobic ability, the changing of which allowed us to control the collecting power and selective ability of the dialkyldithiophosphates. The studying of the surface activity of aqueous solutions was done using the stalagmometric method and the evaluation of the hydrophobic ability was done in percentage of the relative value of the zinc ion binding in the solution in standard conditions.Studying the influence of surface activity in our designed dialkyldithiophosphate collectors, with their close hydrophobic ability, showed that even with a small increase in surface activity in their aqueous solutions, gold recovery increased by 2-3% in laboratory conditions. Using this enabled us first to apply the dialkyldithiophosphate collector BTF-161 at a plant in Kazakhstan, and then to introduce the specially designed dialkyldithiophosphate collector BTF-163, which has been in use since. Further study of dialkyldithiophosphate activity based on this concept showed us that for the range of short-chain dialkyldithiophosphate collectors with a chain length of up to ?5, the effectiveness of ore processing became lower the higher their surface activity got, with relatively small differences in their hydrophobic ability. For long-chain dialkyldithiophosphates with a chain length of over ?5, ore processing effectiveness increased with the increase of their hydrophobic ability.Based on these studies, a new effective dialkyldithiophosphate collector, BTF-1517, was designed. Using this reagent in continuous gold recovery tests allowed us to reach an 84.21% recovery with a concentrate quality of 15.66 g/t, while using the applied collector BTF-163 in similar conditions led to the recovery of 82.87% with a concentrate quality of 15.65%. As a result, the Kazakhstan processing plant decided to conduct industrial tests with the BTF-1517 collector."

Jan 1, 2018

By D. Steele, B. Ndlovu

"Adequate characterisation of clays is becoming increasingly important as operating mines move into areas of more complex ores. The processing therefore needs better mineralogical characterisation to identify problematic ores for better planning before issues arise. While a number of instrumental mineral characterisation methods are available, X-ray Diffraction (XRD) is widely recognised as perhaps the best technique for the identification and quantification of minerals, particularly clays. When an appropriate sequential and systematic sample preparation and treatment protocol is employed with instrumental XRD analysis individual clays can be uniquely identified, and the proportions of interstratified clays can also be quantified. The effect of sample preparation on the XRD analysis and identification of clays was investigated in this study. The results showed that sample preparation protocol is indeed critical to accurately analysis and characterisation of clays. For example, both dry grinding and micronizing affected the degree of crystallinity of kaolinite leading to the formation of reactive surfaces or changes in the physicochemical behavior. It was also found that the apparent degree of preferred orientation in platy minerals correlates directly with the amount of force/pressure applied during the preparation of backfilled powder samples. This work showed that manual preparation can produce highly variable peak intensities especially with minerals that show any preferred orientation. KEYWORDS Clay; XRD; kaolinite INTRODUCTION Clays are important in our life and they have numerous applications in modern world from cosmetics to environmental remediation. Therefore, clays have been extensively investigated for many years. Adequate characterisation of clays is becoming increasingly important as the mineral processing industry faces more complex mineralogy with the need for better mineralogical characterisation to identify problematic ores and plan accordingly. In most studies, X-ray diffraction (XRD) method has shown the unique capability to characterise mineralogy, especially for the fine grained size materials. The XRD technique is particularly diagnostic for clays. It is known that under ideal conditions, the peak intensities of an XRD diffractogram are proportional to the concentrations of individual minerals present in the sample. Hence, the qualitative mineralogical data obtained from XRD can be quantified, using either the internal or external standard methods. However, it is also known that clays are particularly sensitive to the influences of sample preparation method due to their physical characteristics (e.g. fine grain size, morphology, relative physical softness, crystallinity, thermal sensitivity) that could be destroyed by inappropriate preparation prior to the analysis. Thermal and mechanical treatment and grinding of clays can change their crystalline structure, and consequently, their characterisation results by XRD analysis. The behaviour of clays in grinding has been widely studied, especially for kaolinite (Miller and Oulton, 1970, Milocevic et al., 1992, Tomasevic-Canovic et al., 1992). With prolonged grinding time, the crystallinity of the clays can decrease (Filipovic-Petrovic et al., 2002). It has been shown that grinding may gradually cause the loss of hydroxyl ions of kaolinite (Gonzalez Garcia et al., 1991)."

Jan 1, 2018

By John Starkey

"The development of the Minnovex SAG Power Index (SPI) Test in Canada has created a new and accurate way to measure ore hardness in a SAG environment. Coupled with the standard Bond Ball Mill Work Index Test it is now possible to determine from these two relatively inexpensive laboratory tests, the amount of energy required to grind an ore from the primary crushed size to the desired liberation size. By testing multiple samples to discover where the hard and soft ore zones are located, the representative hardness distribution for the ore body can be determined and grinding equipment selected that is capable to meet production targets for all mining areas of the deposit.In the last century, it was deemed prudent to select up to 50-tonne samples of ore for Semi Autogenous Grinding (SAG) pilot plant tests and a second 5-tonne sample for metallurgical pilot plant work. The methods outlined in this paper show how the 50-tonne sample is no longer required for SAG design because it is better to measure the representative hardness distribution of the ore body than the hardness of a “chosen” representative sample. This is demonstrated to be true by the fact that the lower horizons of an ore zone cannot initially be accessed to recover 150mm pieces, and the bulk samples taken, rarely represent the desired design hardness of the ore. Median hardness will not yield a good result in most cases and a clear understanding of the location and extent of the hardest zones is imperative to achieve a truly successful grinding circuit design.This paper discusses two plants (Kubaka and Agnico Eagle) that have been designed using SPI and Bond with no pilot plant test backup. Both have been very successful in that they can grind design tonnage on the hardest ores in the mine. This guarantees that the mine’s profitability is protected in any mining sequence. It also allows the extra power to be converted to higher throughput on softer ores if additional cash flow is needed. The advantages from the owner’s point of view are dramatic. This procedure will be attractive as well when considering the costs for test work, and the samples for testing. Existing diamond drill core is normally used and this allows the inclusion of data from the deepest regions of the mine. In addition, it is also clear that the decision to use a crusher can now be made at the design stage of a project based on measured parameters and the estimated capital costs of alternative designs."

Jan 1, 2003

By L. Ya Agapova

Emissions from pyrometallurgical processing of copper concentrates are usually subjected to wet scrubbing. The washing sulphuric acid so produced contains up to 0.2 g/L of rhenium, which is recovered by solvent extraction in the form of crude ammonia permeate (NH4ReO4). The mother liquor, obtained from the sulfuric acid wash, contains up to 35 g/L of rhenium and significant amounts of impurities. Crude rhenium salt is commonly processed by double recrystallization to produce marketable salt. A ton of high grade NH4ReO4 can be produced using 3.0-3.5 m3 of mother liquor. We propose an efficient technology of mother liquor pre-treatment aimed at removal of water-soluble organics with subsequent electrodialysis. Electrodialysis of mother liquor in a multichamber electrodialyzer resulted in the production of pure rhenium acid, from which a marketable NH4ReO4 is precipitated using ammonia solution. Multiple steps of recycling consisting of dissolution of NH4ReO4 salt, rhenium acid production from NH4ReO4 salt by electrodialysis and precipitation of NH4ReO4 from rhenium acid made it possible to upgrade the purity of obtained rhenium compounds by 1-2 orders of magnitude. A rhenium metal powder of 99.997% purity was produced by high-temperature reduction of high-purity NH4ReO4 with gaseous hydrogen. Rhenium metal powder of high purity can be produced from sulfate solutions of NH4ReO4 by non-platinum anode-based membrane electrolysis processes also. Keywords: rhenium, mother liquors, membranes, electrodialysis, rhenium acid, ammonia perrhenate, reduction, powder, electrolysis

Sep 1, 2012