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By V. V. Ramarao

Grinding and flotation operations deliver better-optimized performance when they are monitored and controlled in terms of the minerals they process rather than as elemental assays that we usually refer to. Mesh of grind (MoG), liberation, floatability, grade and recovery etc. are more directly related with the minerals and their characteristics rather than the elemental assays. Hence, online analyzers only provide the status for the grade and recovery of metals and not the direction for the enhanced performance. Central Research and Development Laboratory (CRDL) and Rampura Agucha Mine (RAM) mill section of Hindustan Zinc Limited (HZL) jointly undertook various survey campaigns in the grinding and flotation process streams. Grinding circuit surveys involved systematic collection of representative samples from different grinding circuit streams under stabilized conditions for monitoring particle size and process mineralogy details across individual grinding circuit. Flotation survey campaigns included study of fort-nightly / monthly composites of un-ground flotation feed, lead concentrate, lead tailing, zinc concentrate and final tailing samples for size distribution details in the 150 ? 38 micron range, chemical analysis and mineral characterization through optical microscope. This work details the investigations results and their implications on beneficiation performance. Grinding circuit survey campaigns supported the task for modifying the originally installed configuration of hydrocyclones, to limit recovery losses due to excess grinding of soft galena and related silver minerals. Flotation plant surveys helped in adjusting flotation circuit process parameters to reduce loss of liberated and floatable galena and sphalerite grains into their respective tailing streams. Keywords: grinding circuits, survey campaign, hydrocyclones, mineral liberation and locking, lead-zinc ore beneficiation operation

Sep 1, 2012

By R. Kobialka

In the article results of experiments over jaws? linings in jaw crushers with different shaping of working surface were presented. Following sets of jaws were under investigation: immobile plain jaw and moving jaw with grooving surface. Grooving jaws have groves with circular, triangular and trapezoid cross section. In order to evaluate efficiency of comminution both the grain composition of product and the content of irregular grains were determined, as well as the size of crushing forces and process efficiency were measured. For the combination: plain jaw with grooved one, a good results were obtained as regards the grain composition of product and the content of irregular grains. Crushing forces were higher at crushing with mixed types of jaws (the one plain, the second grooved), in comparison to crushing with using both grooved jaws. Efficiency of the process was definitely higher for mixed jaws.

Jan 1, 2014

By U. Ulusoy

Surface roughness and acuteness are known as the two of the main properties of the particle morphology affecting the behavior of the powders in the process. Since the techniques used for the morphological characterization of powders by 2-dimensional microscopic measurement from the polished sections that have some disadvantages, the 3-dimensional analysis has often relied on measurements of particle morphology. A review of literature data was presented for high-grade barite and pyrite particles ground by ball and autogenous mills to determine the morphological properties using a new 3-D approach based on BET nitrogen gas adsorption and Permaran methods. Micromeritics Flowsorb II 2300 instrument which employs BET nitrogen adsorption technique was used for the specific surface area measurements and the roughness of the particles. Permaran (manufactured by Outokumpu Oy) was used for the measurements of airflow resistance of powder samples for the acuteness. Spherical glass beads were used as reference sample for the acuteness measurements. The obtained parameters, which are surface roughness and acuteness, were corre-lated with the floatability performance of those mineral particles. The flotation performances of those particles ground in different mills (ball and autogenous) were also evaluated by a Hallimond tube. The results showed that lower roughness and acuteness values caused higher flotation recoveries for both barite and pyrite particles that were tested independently in different type of the mills. In other words; particles with smooth surfaces resulted in better floatability for barite and pyrite minerals studied.

Jan 1, 2014

By J. Qiu

By means of natural sedimentation, two different bentonite samples from Shandong province were purified, this paper studies the Hydro-properties of the two purified montmorillonite samples. Firstly, the layer charge of two purified montmorillonite samples were calculated by crystal structure formula reckon method and general hydro-properties were also measured. The research results showed that the layer charge of montmorillonite correlated well with its hydro-properties: mont-morillonite with lower layer charge had better hydro-properties, such as Mont-1, which had higher swelling volume and gelling value with lower CEC; while, montmorillonite with higher layer charge had worse hydro-properties, such as Mont-2, which had lower swell volume and gelling value with higher CEC; it proves that the hydro-properties of montmorillonite depends on its layer charge characteristics, layer charge characteristic is the inherent factors deciding the hydro-properties of montmorillonite, montmorillonite with lower layer charge has better hydro-properties than the one with higher layer charge. In this paper, the relation between the medium condition and colloid performance of Mont-1 are also studied. The results show that the hydro-properties of Mont-1 could be changed by changing slurry concentration (w/w) and shear rate or adding certain amounts of inorganic cation electrolytes, dispersants and surfactants. The viscosity of montmorillonite slurry could be enhanced by increasing slurry concentration,adding univalentcation electrolytes (less than 4% w/w) or proper amounts of dispersants and surfactants (less than critical micelle concentration); The slurry viscosity could be reduced by decreasing slurry concentration, increasing shear rate, adding proper bivalent (more than 4% w/w) cation electrolytes or proper quantities of dispersants and surfactants (more than critical micelle concentration).

Jan 1, 2014

By Andrew Logan

Newcrest has a strong history of growth over the past 20 years, yielding value from previously marginal ore bodies. We have grown regionally in Asia Pacific through our operations in Australia, Indonesia and Papua New Guinea, and also established a beachhead in West Africa. The company has a reputation of realizing value from large, low-grade deposits adopting step change approaches. Newcrest is focused on an overall strategy of gold, low cost, long life and moderate growth. Capability step changes play a large delivery role. They transition from a business offline-to-online approach as opportunities mature. Newcrest believes in a) Knowing what ?good? looks like, b) An open innovation approach to actively working with others, c) The leap frogging leverage of making the ?old new again?, d)An adopt-adapt-develop methodology enabled by rapid prototyping/piloting, e) Getting our handsdirty with test work and plant analysis, and f) Staying focused on a few high business leverage areas. This paper describes Newcrest?s approach and our experiences in establishing renewed metallurgical processes, specifically aimed at increasing innovation adoption. Some of our step changes discussed include: 1) Early waste rejection to avoid high energy processing downstream, 2) Broader gold product channels to reduce site based processing needs, 3) Lower energy processing, and 4) Geo-Metallurgy approaches. Keywords: Newcrest, gold, step change, open innovation, adopt, adapt, develop, offline, online, prototyping, old new again, waste rejection, low energy, geo-metallurgy

Sep 1, 2012

By F. Q. Dong

According to the principle that should be originated from nature, compatible with nature, used in nature and back to nature and based on conception of designing of eco-material, the author combined the ideas of material, environment, zoology and healthy. Properties of natural mineral materials were used to produce micro-aggregate elements by bionic method, so its components and function could accord with living environment. Eco-mineral functional materials which can adjust, purify and optimize the microclimate were reviewed. The authors pointed out the multifunction, com-pounding, the compound characteristics and integration regularities of micro-aggregates. It was the first time in the world to put forward the ?gene? technique or ?material chip? technique of manufacturing function micro-aggregates and eco-function elementary materials. The results of this re-search supported by the national ?863? Hi-tech Project, mainly including the high-efficient air purifying mineral compound material indoor, the clay elementary antibacterial materials, the masonry cement/coating/putty/compound with preventing radon radiation, environmental friendly composite functional coatings, mosquito repellent and healthcare material and zeolite-based energy-saving composite materials, were introduced. Finally, the foreground of mineral materials in the field of future advanced eco-friendly materials was also discussed.

Jan 1, 2014

By A. S. Choudhary

India is endowed with a reasonably large reserve of chrome ore, amounting to about 100 million tons in different grades and is one of the leading producers of ore/concentrate along with South Africa, Kazakhstan and others. Chromite production in India has registered a 10 times increase during the last 30 years. Till late 1940s, the practice was to mine the high-grade ore for making ferrochrome and charge chrome and export the same leaving the low and medium grade ores stacked around the mine as waste material. This practice was continued for quite some time till the increase in world wide de-mand of chromite initiated an increase in production of chromite ore in India and the aspects of ?economy of operation? and ?conservation of mineral? dawned on the producers and associated authorities. Recovery of chrome values from low and medium grade ore was initiated to produce high-grade saleable concentrate. Suitable legislation was made by Government of India to induce and provide incentives to the operators to do so. First large scale chromite beneficiation plant in India was commissioned about three decades back at Byrapore in the Southern state of Karnataka. The ore, rather simple in nature and relatively free from clay, was obtained from underground. The processing consequently was simple washing and wet tabling. Further more, some test work, on the samples from eastern coast particularly from Orissa, was carried out at an internationally reputed laboratory by a large private operator and the plant was set up. This consisted of a combination of crushing-grinding-de-sliming-classification followed by concentration in multi stage spiral concentrators and shaking table. The plant was commissioned and operated successfully. Soon a state owned company followed suit on the basis of test work carried out in a well equipped Indian laboratory. The plant worked satisfactorily after some initial teething trouble and the company plans to double the existing plant capacity by installing balancing facilities. This development prompted a number of operators, including industry leaders to join the fray and the chrome ore processing industry flourished in India. More and more operators are now in the process of adding capacities to their existing plants. This paper attempts to chart the evolution of chrome ore beneficiation industry in India through a case study with reference to an existing plant. The process technology adopted and modified to suit the altered requirements as well as the future trends are outlined.

Jan 1, 2014

By M. Bhartia

India is the 5th largest producer of steel in the world and is slated to produce more than 180 Mt by 2020. Expectedly about 50 % of this would be through the Blast furnace route and the rest through Sponge iron / DRI route. Considering that there will not be any major change in iron making technology by that time, the Blast operation would require lump ore (10-40mm) with around 64% Fe grade and sinter fines (<10mm) with 60% Fe (min) as its feed. DRI process would need calibrated ore of size 5-18 mm as the most suitable size of feed. It is also expected that of the total requirement of ore for the DRI route a significant part would be DRI pellets. In India, there is considerable debate going on regarding the technology to be adopted for the processing of iron ore and there is a lack of clear consensus. The above scenario indicates that the processing requirement of iron ore in the country would involve both washing technology as well as beneficiation technology. CDE Asia Ltd is in the forefront of iron ore processing in the country and the experience gained by the company over the last few years of functioning has led the company to believe that route to be adopted depends on the end product requirement and the starting grade of the feed. Keeping in mind the nature of the feed required for the Blast furnace & DRI operation; it is obvious that good washing technology would be highly beneficial to the iron ore industry. Depending on the grade of ore available the limits of washing will be decided and equipment for lump ore beneficiation such as jigs could be incorporated into the washing circuit. Scrubbing of ore either before washing or selectively scrubbing the lumps could be necessary. Very low grade ore and jig rejects would be required to be totally ground and beneficiated for the production of pellet feed in order to utilize the iron ore resources entirely. Another source of ore for pelletisation would be slimes generated from the washing process as well as the huge quantities already available in the tailings dams in the operating mines. Deslimimg and magnetic route of beneficiation could release at 30-40% of the Fe locked up in these tailings ponds/dams. The paper describes the concept with examples from operating plants and proposes how the adoption could be engineered through test work and proper plan of integration. Keywords: washing, beneficiation, iron ore, lumps, sinter fines, pellets, jigs, screens, evowash, nanowash, thickeners, log washers, drum scrubbers

Sep 1, 2012

By Heramb M. Bal

This paper will underpin the future development of intellectuals having greater understanding of patent law and legislation, IP rights, and innovation. To understand this idea, I present a case study of China?s progress in the last 31 years in the rare earth research, innovation, and simultaneously patents area. Rare earth elements (REE) are at the centre of high technology and are the next wave of world innovation. Much of modern society depends on rare earth elements through their use in computers, lasers, telecommunications, iPods, medical technology, military applications, and so on (Long et al, 2010). The rare earth research, a large research body is being provided by Chinese sources. China devoted three or four university centers to the study of rare earths (Lifton, 2009). These measures are all designed to keep China at the forefront of REE production, materials, technology, and innovation. As a result in the last fifteen years there has been a shift from a US-dominated REE industry patents to Chinese patents. The world must identify strategic areas of rare earth innovation and provide funding to firms and universities that conduct such research. Not only research and innovation is vital but filing patents and preserving IP rights for research and innovation is even more important. We (rest of the world) need a comprehensive strategy to guide the development of patent and IP rights for research and innovation. To achieve this, the development of intellectuals with superior knowledge of patents and IP rights are the future need of minerals industry. Keywords: innovation, rare earth, patent, IP rights

Sep 1, 2012

By Bertil I. Pålsson, Sture V. Persson, Kent T. Tano

"Grinding is one of the most energy consuming unit operations and is also a very inefficient and costly process. Therefore, it is of great importance to run the grinding process as efficiently as possible. The most common way today to control grinding processes is by measuring the power draw of the mill and try to keep it at a maximum level. However, some studies (Kawatra, 1989, Koivistoinen, 1989, Moys, 1989) have shown that this measurement doesn.t reflect everything that takes place inside a mill. Among other parameters like slurry rheology, temperature and charge behaviour, the volumetric filling of a grinding mill seems to have a large influence on the grinding efficiency (Herbst, 1988, Koivistoinen, 1992, Vermeulen, 1988). A problem in attempting to measure those parameters has been to get a sensor that is both robust and sensitive enough for continuous on-line measurement.This paper presents a method for the measurement of the apparent filling level in a pilot ball mill equipped with the Metso Continuous Charge Measurement system (CCM). In this technique a strain gauge sensor is mounted on a flat steel spring which is fitted into a recess underneath a lifter bar. In addition, a conductivity probe, the Boliden Grinding Measurement System (GMS), is mounted in another lifter bar with the purpose of comparing the two measurements. To visualise the behaviour of the charge a DEM modelling technique is used.The results indicate that the system is capable of following the normal variation that occurs in the mill. The signal also very well reflect changes in operating variables such as ball charge level, pulp density and rotational speed. By studying the nature and different features of the signal one can get a better understanding of milling circuit dynamics. Another feature of the technique is the possibility for an operator to continuously follow the grinding process and thereby run the process under optimal conditions."

Jan 1, 2003

By Pat Turner, Abrie Schutte, Tim Olson, Roman van Ommen

The key to good cyclone circuit design and operation in primary grinding circuits will be discussed. Cyclone circuit design issues include individual cyclone design features such as cone angle or materials of construction, as well as orientation and manifold configuration. Cyclone performance issues as well as maintenance considerations will be detailed in an effort to achieve consistent cyclone operation with minimal coarse solids in the overflow. The new gMAXTM. cyclones will be introduced and evaluated using operating circuit data in closed circuit grinding applications

Jan 1, 2003

By L. Q. Luo

SHP-F3200 wet high-intensity magnetic separator (HIMS) was successfully used to separate the complex and weakly magnetic iron ores being composed of specularite, limonite and siderite in Ji-uquan Iron and Steel (Group) Co Ltd (JISCO). It is more and more difficult to separate iron ores from gangues, such as quartz, jasperite and phyllite, as the properties of iron ores gradually become more complicated and refractory. Some technologies have been used to improve SHP-F3200 HIMS, including modifying angle of magnetic polar from 90°to 83°, cooling exciting coils by oil instead of air, adding reverse-washing device to wash off magnetic particles, adjusting the tooth-space of matrix from 5.0 mm to 3.5 mm or 2.5 mm, so as to enhance the recovery of fine iron ore particles. It is still difficult to meet the requirement for recovering more difficultly-separated iron and the demands for high-grade concentrate of iron. In this paper, after analyzing magnetic force exerting on iron ore particles within different separating sections of SHP HIMS, it is proposed to apply the flowing-film technique into the HIMS. Thus a new-type LY matrix is designed to form magnetic gradient vertically, combined with a special flowing-film feeder to improve the existing SHP HIMS. The moving pattern of magnetic particles in pulp in HIMS separation district also has been analyzed in this paper. And the test on the SHP-F700 HIMS shows, under the condition of iron ore containing 30.52% Fe, with particle size of ?0.074 mm accounting for around 75%, if applied with flow-film technique, the iron recovery will be up from 69.45% to 76.07%, by 6.62 percent, with the same grade of concentrates of iron. The calculation of iron yield of every size fraction and the tests showed that film magnetic separation (Film-MS) could promote the iron yield of each size fraction, denoting an excellent result of application of the film technique to SHP HIMS. The mechanism of the film magnetic separation technique is to convert the turbulent flow and disordered movement of dynamic mass particles in the pulp into a directional and ordered laminar flow along the surface of tooth plate so as to strengthen the separation effects.

Jan 1, 2014

By G. Y. Liu

The structure-activity relationships for four thionocarbamate collectors are discussed in this pa-per. These collector classes are alkyl alkyl thionocarbamates, allyl alkyl thionocarbamates, acyl al-kyl thionocarbamates and alkoxylcarbonyl alkyl thionocarbamates. The main emphasis will be to highlight the differences between collectors and their affinities for copper and iron sulfide minerals on the basis of data on electronic-structure properties obtained by vacuum and solution density functional calculations, flotation experiments and analysis measurements. The mechanism of interaction of these collectors with sulfide minerals is also discussed with perturbation theory. The theoretical study results indicate that acyl alkyl thionocarbamates and alkoxylcarbonyl alkyl thionocarbamates have best performance in these agents as flotation collectors with improved collecting power for copper sulfide minerals and excellent selectivity against iron sulfide minerals, which are consistent with the experimental data reported in the literature.

Jan 1, 2014

By A. J. Lynch, D. K. Tungpalan, Y. Reja, E. C. Avelar, G. Figueroa, S. Gómez, R. Alanis, M. A. Corona-Arroyo

"Have you been on a mine site? This question was posed by Emeritus Professor Alban Lynch to Higher Degree by Research (HDR) Students from the Sustainable Minerals Institute - Julius Kruttschnitt Mineral Research Centre (SMI-JKMRC) in the Student Technical Presentations in 2015. From that question, five HDR students from SMI-JKMRC organised a placement on mine sites in Mexico. The SMI-JKMRC is well known for its tradition to provide their students with opportunities to enhance and test their skills in mineral processing plants. The Student Venture became a short internship for HDR students which had the objective of establishing collaboration with mining companies in Australia and overseas, and of providing a unique experience for the HDR students in regard to their training, professional development, networking and cultural interchange. In return for the companies’ support, the students conducted plant audits to evaluate the process performance thereby providing valuable data to the host company. The 2016 Student Venture was held at the Grupo Peñoles & Grupo Fresnillo in Mexico, in which three mine sites received five HDR students from JKMRC and one young researcher from Universidad de Guanajuato (UG). This paper describes the positive outcomes for the mining company and the students for this experience. The Venture was considered very successful, as it provided valuable training for the students as well as in depth information about the operation of the comminution and flotation circuits of the host sites for the Grupo Peñoles & Grupo Fresnillo. The experience also provided an opportunity for an exchange of knowledge between the HDR students and the site personnel from the host operations. The indication of the success of the experience for all involved was the support of the host company in future student internships."

Jan 1, 2018

By ?. S. Potokin

"In general the electric pulse treatment is composed from two processes – electric pulse grinding and electric explosive (electric discharging) activation. The electric pulse grinding with the effect of selective destruction refers to a major slag fraction, more that 2-5 mm, when a one can see a physical prerequisites for electrical breakdown of the slag particles. The electric pulse treatment of slag is considered as an additional operation in the technological scheme extraction of non-ferrous metals from copper smelting slags in addition with mechanical grinding, flotation enrichment and acid leaching. Studies of the reprocessability of pelletized slag have shown the possibility of higher extracting non-ferrous metals via flotation after electric pulse disintegration (EPD) treatment. By using EPD of slag pellets, it is possible to increase the non-ferrous metal yield to concentrate by 18-24%.INTRODUCTION The use of the explosive effect of the plasma discharge channel at electrical breakdown of a solid at a pulsed high voltage is the physical basis of the electric pulse method of destruction of geomaterials (Vorobiev et al., 1971; Andres, 1995; Semkin et al., 1995). The flowing of a pulsed current in the discharge channel is accompanied by a sharp increasing of plasma’s temperature and pressure, leading to a supersonic expanding of the discharge channel, the formation in the solid of intensive mechanical tension field, spreading of cracks, and eventually, to the destruction of the solid. Fragmentation and grinding of ore and mineral aggregates by electric pulse method due to a number of specific physical mechanisms of power load and crack formation, belonging only to this method, is different by high selectivity of destruction. This ensures better liberation of grains of individual minerals and their better preservation from destruction and less formation of a slurry output. These features creates the prerequisites for a more complete extraction of a useful mineral in the concentrate during ore dressing, to improve the quality of concentrate. In contradistinction to mechanical methods, electric pulse technology does not contaminate the product with instrumental metal, material of lining and grinding bodies. The possibility simply and in a wide range to change the dynamic load character allows to regulate the granulometric composition of the product of grinding, to obtain a narrower class of product size than is possible with mechanical grinding. The product of electric pulse grinding is characterized by less roundness and large specific surface area of grains due to the trait, that a new surface is formed in the process of splitting during the expanding of cracks. The degradation product has increased sorption and reactivity in chemical reactions. Liberation of the mineral inclusions particle better corresponds to their initial natural state in the rock and this is the great importance for the study of mineral raw materials."

Jan 1, 2018

By Carmina Quintanar, Mario Palominos

"The mining industry is currently facing significant challenges to identify and adopt sustainable collector chemistry that effectively recover value minerals in difficult-to-process low-grade resources. These are typically characterized by complex mineralogy and the presence of significant amounts of penalty gangue sulfide minerals, especially pyrit which is a challenge to separate from value minerals at many major mine operations. Three chemical strategies for dealing with gangue sulfides and penalty elements are: a) selective flotation of value minerals while rejecting penalty minerals in the whole circuit, b) rejecting penalty minerals in an appropriate part of the circuit using selective depressants, c) using a combination of selective collectors and depressants in appropriate parts of the circuit. This paper will evaluate different strategies for dealing with those penalty elements and propose the most efficient alternative. New products and application technologies have been developed in the past 25 years by Cytec for implementing these strategies as dictated by the particular needs of a given plant. However, in recognition of the growing interest in meeting the sustainability challenges, Cytec Research and Development have been focused in the development of greener products (collectors, modifiers and frothers) and processes using FLOTATION MATRIX 100TM approach used to develop the optimal collector system for each specific ore. An overview of these new developments is given in this paper using case studies of application of selective collectors and polymeric modifiers including the newer, greener chemistries."

Jan 1, 2014

By Q. Zhang

The flotation behavior of jamesonite was investigated with ethyl xanthate as a collector. It has been shown that jamesonite has good floatability from pH 2 to pH 12, and relatively poor floata-bility at pH>12. The flotation of jamesonite was also dependent on pulp potential at certain pH val-ues. The potential-pH range for jamesonite flotation was established. The FTIR spectroscopy analy-sis and XPS measurement showed that the major adsorption product of ethyl xanthate on jamesonite was lead ethyl xanthate and antimony ethyl xanthate. The intensity of the FTIR signals of metal ethyl xanthate adsorbed on jamesonite and the flotation response of jamesonite were correlated with pulp potentials.

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 Bharat Garg

The coking coal or clean coal from raw material division, Tata Steel Ltd. is a prime source of energy for inhouse steel making. Coal reserves of semi soft coking coal at West Bokaro is beneficiated by dense media cyclone and froth flotation processes to produce clean coal. In dense media cyclone process two byproducts-middling and rejects are also produced along with clean coal. With the growing demand for clean coal, it becomes imperative to maximize the recovery of clean coal in beneficiation processes. This will help, not only in reduction in cost of production, but also in raw resource conservation, and proper utilization. In this context, a case study was conducted at West Bokaro to identify opportunities for clean coal recovery from by-products. This paper mainly discusses the process for recovery of clean coal from byproducts and study of further liberation of clean coal from byproducts for economic consideration.

Sep 1, 2012

By T. V. Chnyrenkova, J. Troncoso, V. A. Luganov, G. P. Kluev

"Arsenic-gold bearing ores are used as flux in smelting or are leached to extract gold. The main aim is to decrease the arsenic content in processed materials and to break up the ore lattice, thus liberating the gold. Some regulations were established by authorities for sulfidizing of arsenic bearing compounds in a presence of pyrite and for oxidation of ores and concentrates in the presence of soda.This article analyses the results of laboratory and pilot plant testing of dissociating and oxidizing roasting of gold-arsenic bearing concentrates. During the dissociation roasting under vacuum, arsenic is sublimated into elemental and sulfide forms. This process allows for the minimization of the negative influence on the environment, but requires costly engineering solutions. Roasting in a limited quantity of oxygen in the gaseous phase makes it possible to sublimate arsenic in the form of oxides and sulfides and it may be carried out in fluid bed furnaces.Oxidizing roasting of the concentrates in the presence of soda results in formation of water-soluble compounds and forces practically all arsenic and sulfur to remain in the cinder."

Jan 1, 2003