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By A. M. S. Hussein, B. E. Rogers

Progressively more stringent emission limits and advances in regulations and enforcement have made air compliance more difficult for metallurgical facilities. This has historically required improved collection and treatment of stack sources. Fugitive emission reductions are now increasingly required to achieve compliance. Typically small in magnitude, fugitive emissions have a disproportionate impact on ground level concentrations, can be visible to the public and can influence workplace health and safety. Moreover, these emissions are complex, as they are spread over multiple sources, distance and time and are affected by various activities and conditions. As such it is difficult to find, define and monitor these emissions and their impacts. This difficulty translates to the design of emission reduction measures and operational requirements. This paper presents an overview or ‘heuristic’ of fugitive emissions management for compliance in existing operations. This includes aspects such as the impact of regulations on project scope, approaches to developing a comprehensive emission inventory, considerations for solution development and the plant’s role in sustaining compliance once achieved. Case studies are presented to demonstrate how portions of this approach have been applied.

Jan 1, 2015

By J. A. Jr. Carpenter

Expanding world economic prosperity, probable peaking of conventional petroleum production in the coming decades and environmental concerns require efforts to increase the efficiency of, and the development of alternatives to, petroleum-based fuels used in automotive transportation. In January 2002, the U.S. Department of Energy (USDOE) and the U.S. Council for Automotive Research (USCAR) of the "Big Three" traditionally-USA-based automakers, DaimlerChrysler, Ford and General Motors, formed the Freedom Cooperative Automotive Research (FreedomCAR) Partnership to fund high-risk, high-payoff research into advanced automotive technologies with the potential for eventually lowering the USA's nearly complete (95%) dependence on petroleum, 55% imported, for its transportation fuels. FreedomCAR replaced the Partnership for a New Generation of Vehicles (PNGV) which existed from 1993 to 2001. In January 2003, the energy-supply industry joined with the FreedomCAR Partnership forming the FreedomCAR and Fuel Initiative (FC&FI) to develop the technologies needed for the mass production of fuel-cell vehicles using hydrogen as fuel and the infrastructure needed to deliver the hydrogen to the consumer. The goal is to enable the automotive and energy-supply industries to make commercialization decisions in 2015 on large-scale introduction of such vehicles and on developing the infrastructure beginning in 2020. In addition to work on fuel cells and hydrogen infrastructure, the FC&FI conducts research on technologies with the potential for nearer-term energy efficiency and environmental benefits, such as new engine concepts, lightweight materials, and engine-electric hybrid propulsion systems. Lightweighting is seen as crucial for shorter and for longer term benefits because hybrid and fuel-cell powertrains are expected, at least in the early stages of adoption, to be heavier and more costly per unit of power than the standard internal-combustion, gasoline- or diesel-fueled powertrains they replace. Research and development (R&D) on casting of aluminum automotive components were major parts of the PNGV and R&D on casting of magnesium automotive components have been and are so under FreedomCAR. This presentation will review those efforts.

Jan 1, 2006

By D. Bois, P. Keating, J. Lemieux, M. A. Vallée, M. Allard, R. S. Smith, L. Z. Cheng, M. Chouteau, K. Fountain

"A comparison of data from INPUT, GEOTEM, and MEGATEM airborne electromagnetic (AEM) systems over the Aldermac deposit, Québec, Canada, was undertaken to evaluate the relative ef¬ficiency of these systems for the detection of small, deep conductors. The Aldermac orebody was mined between 1933 and 1934 to a depth of 200 m. A deeper mineralized zone was discovered in 1987. The MEGATEMII system was used to acquire 90- and 30-Hz data over the deposit in 2003 as part of a research project. These MEGATEMII data were compared with data acquired by other AEM systems (GEOTEM and INPUT), and the results show that the MEGATEMII response is ten times larger than the other sys¬tems. For the dB/dt response, 30 Hz gives a better signal-to-noise ratio, whereas 90 Hz has a better signal-to-noise ratio on the B-field.The data were evaluated by numerical modeling. The deposit was best represented by a complex mod¬el, comprising two weakly conductive bodies to approximate the alteration halo, two deeper prisms repre¬senting known orebodies, and three bodies ranging in thickness from 3 to 6 m and in resistivity from 12 to 20 ohm·m, representing the chargeable overburden. This implies that the MEGATEMII system is able to see a small conductive body at more than 200 m depth in an area where the response is contaminated by conductive overburden."

Jan 1, 2009

By Dayle Denton, Lloyd Buckingham, Kenneth G. Thomas, Jacques McMullen

"The dry grinding and leaching circuits of Barrick Gold’s new Roasting Facility at Goldstrike Mine in Nevada, USA incorporate well proven technologies in a unique combination. During the design of the plant, every effort was made to utilize the best available technologies from the perspective of capital, environment and operating costs.Crushing is a two stage process using gyratory and cone crusher. Ore is stockpiled and then reclaimed to two parallel dry grinding mills. The double rotator dry grinding mills include a drying chamber, coarse and fine compartments and utilize a gearless motor drive (GMD) or “wrap-around”. In-circuit product transfer is accomplished with air slides and bucket elevators. Finished product separation is performed by both static and dynamic classifiers with the final product captured in baghouses. Recycle of unfinished product utilizes cascade chutes.The final ground product reports to two 2000 ton roaster feed silos. The two-stage oxygen flu-solids roasters with their associated gas train are the subject of a separate paper.The cyanide leach circuit is a standard carbon in leach system with circular swept screens for interstage carbon retention. The loaded carbon is sent to the existing Goldstrike autoclave plant for stripping and regeneration. Tails, after cyanide destruction, are deposited in the existing tailings dam with tails from the autoclave facility.Throughout the circuit, Clean Plant Design criteria were used to assure environmental compliance, ambiental acceptability and ensure worker health and safety. The commissioning and operation of the double rotator grinding technology has been very successful at Barrick Goldstrike."

Jan 1, 2001

By D. Kachongo, Y. Cheng, A. Kashala, D. Samal, G. Mitshabu

Many copper processing flowsheets in the Democratic Republic of Congo include the leaching of oxide ores containing copper and cobalt, copper solvent extraction, copper electrowinning, and precipitation of cobalt salt. Recently, cobalt price gained momentum, driven mostly by the fast-growing electric vehicles battery market. The ore blending scenarios tend to prioritise high cobalt grade ore, whatever the content of copper and other impurities. Therefore, many copper solvent extraction circuits are running below design capacity. The variability of feed induces a variability of the leach solution with respect to copper, manganese, and silica contents. It is thus important to adjust hydrodynamic and metallurgical parameters of the solvent extraction plant to optimise metallurgical performance, production cost, and the quality of the copper electrolyte. This paper presents some results on how solvent extraction plant parameters have been managed in two solvent extraction plants running with lower than designed copper input. INTRODUCTION Referring to a report of the chamber of commerce of the Democratic Republic of Congo (DRC) the online publication Agence Ecofin (2019) indicated that the DRC ranks in the fifth position of the world top copper producing countries with over 1.2 million tons produced in 2018. The same year, 66% of the world’s cobalt was produced in the DRC at over 106,000 tons. If the political situation remained stable and the new tax regime introduced in 2018 did not deter private investors, copper production could reach 1.4 million tons/a in 2020 as pointed out in Mining.com (2019). Forecast figures for DRC cobalt production vary widely depending on analysts. The DRC online magazine Actualité.cd (2018) referring to a ministerial source forecasts over 141,000 t cobalt/a for 2020. The reality will depend on many factors, including the selling price, the supply compared to the demand, and finally the reaction of investors to the new DRC tax regime. The growing electric vehicle batteries market has been the major key driver of the price of cobalt. The five years historical cobalt price graph in figure 1 from infomine.com (2019) shows that the price of cobalt peaked at over 40 USD/lb in the first quarter of 2018. Cited by the online Magazine Creamer Media, Smith (2019) has indicated that the long-term demand of cobalt will likely remain strong.

Jan 1, 2019

By George Kellock

Introductory The Alberta Provincial Government has contemplated a revision of the Mines Act for some time past, and it is understood that a definite decision has now been made to do this at the next session of the Legislature. The Operators' and Miners' organizations of the Province have been asked, or at least have been given the opportunity, to submit their views and ideas relative to the proposed changes. The operators have already drafted out a number of changes which they feel would improve the Act from the standpoint of safety and practicability, and this paper has been prepared so that the general membership of the Rocky Mountain Branch of the Institute, which is composed largely of the operating and certificated officials of the mines, might have an opportunity to discuss, criticize, and improve upon the suggested changes which the operators are putting forward.

Jan 1, 1929

By J. R. Emery, D. F. Coates

"FOUR PAPERS ON CEMENTED BACKFILL were given at the Annual General Meeting of The Canadian Institute of Mining and Metallurgy in 1970:Weaver, W. S., and Luka, R., ""Laboratory Studies of Cement-Stabilized Mine Tailings"".Pasieka, A. R., Beattie, H. F., and Espley, G. H., ""Cemented Hydraulic Backill within the Falconbridge Group of Companies"".McLeod, P. C., and Schwartz, A., ""Consolidated Fill at Noranda Mines Limited (Geco Division)"".Clement, W. P., and Sokoloski, R., ""Pumping Cemented Backfill"".These four papers give the impression of a development in mining technology that has been substantially completed. Somewhat over ten years ago, The Inter-national Nickel Company of Canada, Limited and Falconbridge Nickel Mines Limited started experimenting with the addition of Portland cement to mill tailings to produce improved backfill and cheaper floors for scraping. Shortly after, the Canada Cement Company Limited (now Canada Cement Lafarge Ltd.), with full support of the two mining companies, started an extensive research program to provide the technologic-al data necessary to exploit what was obviously going to be a significant development in mining technology."

Jan 1, 1970

By R. A. Campbell

The electric smelting of five lowgrade Canadian manganese ores has been investigated at the Mines Branch, Department of Mines and Technical Surveys, Ottawa. Ferromanganese, silkomanganese, and spiegeleisen were produced 1by special smelting processes from these ores since the latter were too low grade to be treated by conventional smelting methods. In one case the results were considered to be sufficiently promising to justify the construction of a pilot plant, by the Company concerned, for the further development of the process.

Jan 1, 1956

By H. Utsunomiya, J. Su, K. S. Tamimi, S. Yue, M. Sanjari, L. Kestens, Hara, A. S. Kabir, R. Petrov

Manufacturing of thin sheet is difficult in industries. Some approaches, such as small-draft multi-pass rolling, intermediate annealing, isothermal rolling and high-speed rolling were proposed to overcome the deformability. In this study, different rolling speeds from 15 to 1000 m/min were employed to twin rolled cast AZ31B magnesium alloy to different reductions. The results show thatAZ31B sheets rolled at 15 m/min and 100 °C has fractured for reductions of more than 30% per pass. However, by increasing the rolling speed to 1000 m/min the rollability was improved significantly and the material can be rolled to reductions of more than 70% per pass. The high speed and heavily deformed materials are fully recrystallized even at 100 °C.

Jan 1, 2014

By Wm. L. Giachino

"Over the last 10 years, C-1-L has played a significant role in the major advances that have taken place in blasting technology, among them the following: development and introduction of capsensitive slurries; development of bulk slurry systems both for underground and open-pit operations; development of the TOE-DET and ANODET systems of delay blasting;introduction of the NONEL system of initiation;development of the Vertical Crater Retreat (VCR) system of mining.This paper identifies areasin which we foresee further developments in blasting technology over the next 10 years and outlines how and to what extent C-1-L will become involved."

Jan 1, 1980

By J. Talja

"Non-ferrous metal concentrates contain typically 7 – 12% water when received at the smelter. Removal of this water prior to smelting is always economically feasible because unnecessary heating of vapour (from 100 °C to 1200 °C) in the smelting furnace can thus be eliminated. This results in major reduction in CO2 emission and direct annual savings of several millions of dollars due to improved energy efficiency. Next step to further improve the energy efficiency, to gain substantial savings and simultaneously cut emissions is to select modern technology for the drying process. Consequently, all CO2 emission will be completely eliminated (from 40,000 tpy down to 0 tpy), NOx emission will be negligible, and the SO2 emission will be reduced by over 99 %. Switching of conventional direct heated drying technology to modern indirect steam drying brings, in addition to dramatic emission reduction, additional savings due to further improved energy efficiency. Direct energy savings count for 900 – 1300 MJ/t H2O, which depending on the concentrate feed rate and its moisture load can be worth several millions of dollars every year. Additional savings in operational expenses related to drying and gas cleaning may be worth a few million dollars more. Sustainability is a key issue today, and major savings together with significant emission reduction are readily available by proper technology selection for concentrate drying. INTRODUCTIONSustainability is a decisive principle in any process industry accompanied with emissions and high amount of energy. This is of significant importance in metal processing, including concentrate drying, where minimum impact on the environment, people and community are targeted, and all this with minimum cost, effort and resources. Therefore, special attention is paid to high energy efficiency, low energy consumption with preferable utilization of waste energy, safety issues, availability, level of maintenance, cost of maintenance, and emissions among other things.Non-ferrous metal concentrates can be dried using various techniques. Conventional drying based on direct heating, and use of fossil fuels for drying energy has almost entirely been replaced by steam drying. It is based on indirect heating and it has become the most dominant drying technology for copper concentrates during the last decade with over 90% of the market share of all new dryer installations. Among the steam dryers the Kumera Steam Dryer is the most pre-dominant technology with some 70% of all new dryer installations world-wide."

Jan 1, 2012

By K. W. Edwards

The formulation of a theoretical basis for the evaluation of in-situ coal through the use of geophysical logs is outlined. This involved the development of an approach to the interpretation of resistivity in environments having multiple conductive and non-conductive components. Utilizing this approach and other conventional interpretation techniques, a program was developed yielding accurate determinations of the in-situ percentages of coal, water and ash for the evaluation of coal deposits. Basic information obtained from the CWA program can be utilized in numerous aspects of total mine planning . Some examples of the practical application of this method are included.

Jan 1, 1978

By Eric Schraml

Wardrop Engineering and the Placer Dome?s Campbell Mine Design Team utilized leading edge directional raise boring techniques and an innovative, remote controlled application of steel fibre reinforced shotcrete ground support to achieve improved mine ventilation and a superior, safety focused secondary emergency egress. While more standardized methods may have provided a sufficient solution to either the requirement for a ventilation raise or for a traditional escape ladder way, innovative methodology ensured both objectives were met with a single, enhanced solution. Placer Dome committed to provide a solution that minimized energy consumption, optimized air delivery and facilitated an escape way focused on minimizing the negative physiological aspects associated with mine evacuation. The project was successful in providing a new airway, returning 47 m3/s (100,000 cfm) from the 39 Level to 30 Level, minimizing risk to the raise equipping crew and providing a fully equipped escape hoist. The resulting secure escape environment provided an efficient means of evacuating personnel working at depth without necessitating a potentially dangerous exhausting climb to surface. The project has substantiated, that optimized safety focused design can be achieved without jeopardizing project economics.

May 1, 2002

By E. A. Lowe, A. F. Bellamy, J. W. Smith

"In the autumn of 1977 Bethlehem management initiated feasibility studies on recovery of by-product molybdenum from concentrate produced at the existing Highland Valley mining operation. Over the fall and winter months test work was carried forward concurrent with design, flowsheet, equipment specification and cost studies. The decision was made to go ahead with a 200 ton-per-day treatment plant. Construction started in early 1978 and progressed to an initial start-up stage in mid-June. Full operational status was reached in August 1978. Operational results through August 1979 are presented. INTRODUCTIONBethlehem Copper Corporation operates a 20,000 ton-per-day Open Pit Mine and Flotation Plant located in the Highland Valley, some 30 air miles Southwest of Kamloops and 20 miles Southeast of Ashcroft, B.C.Two open pits are worked; the Iona Pit with limited reserves of higher Mo content, and the lower grade, more extensive Jersey Pit. Upwards of 150 tons per day of bornite-chalcopyrite bulk concentrate is produced, ranging 0.25% to 1.5% in molybdenum grade depending on the area mined."

Jan 1, 1980

By Stuart McTavish

"Noranda's Goldstream mine is a 1,500 ton per day copper-zinc mine located 60 miles north of Revelstoke, B.C.The orebody which contains 3.69% Cu and 2.69% Zn was discovered in 1972. Construction of the mine and mill was completed in 1982 and start up was achieved in May 1983.This paper will describe the flowsheet and related equipment 1n the crusher and mill, in particular the dewatering section where two Larox pressure filters are used to dry the concentrates.INTRODUCTIONThe Goldstrean property is located 60 miles north of Revelstoke, B.C. in the Goldstream River Valley (Figure #1). It was discovered during the construction of a logging road in 1972. Exploratory drilling was initiated in 1975, and in 1976 a portal was collared to obtain underground data. Samples were taken from the underground workings for metallurgical bench tests and a pilot plant run.Due to economic conditions, the decision to go into production was delayed until 1980. Concentrator construction and underground development progressed simultaneously during 1981 and 1982, and were completed by the end of 1982. Start up of the concentrator was achieved on May 2, 1983.The ore typically contains about 40% sulphides, which are chalcopyrite 10%, sphaletite 6%, pyrrhotite 20%, and pyrite less than 5%. The sulphide minerals have a high degree of intergrowth. Most of the sphalerite occurs in micron sized grains which are embedded in the pyrrhotite and, to a lesser degree in the chalcopyrite. There is also some fine dissemination of the chalcopyrite in the pyrrhotite. The waste rock is made up of about 30% quartz, 20% guange silicates, and 10% carbonates. The ore has a specific gravity of 3.2 and a natural pH of 8.2."

Jan 1, 1985

By O. M. Arafat, J. A. Finch

"The Functional Performance Equation calculated from a plant grinding survey defines two distinct ball mill circuit efficiencies and how they relate to total production rate through the target grind size. The survey data are also used to calculate a complete ball mill size distribution model, represented by the energy specific grinding rates, not just through the target grind size, but through all the size classes. Cyclone separation performance is represented by individual size recoveries to underflow. When these two unit operation performances are entered into the circuit modelling program (Streamline™), along with the circuit feed rate and size distribution, all the circuit survey size distributions and mass flows are perfectly regenerated by the program. The many issues associated with the historical Epstein (breakage-selection) models are eliminated. Once the circuit program is populated, pump and cyclone performance changes can be evaluated using a step-by-step procedure in order to maximize Classification System Efficiency. Mill water use and media sizing opportunities are also diagnosed in order to maximize Mill Grinding Efficiency at the size of interest. An example is provided. This circuit analysis and modelling system, and related training, is provided through a web-based application.IntroductionSince its development (McIvor, 1988), the Functional Performance Equation for ball milling has facilitated new understanding of industrial circuit cause and effect relationships, leading to significant strides in operational performance. Success stories of this refreshing approach to plant circuit performance improvement are now too numerous to list. Finch and McIvor (circa 1986) also discovered that the Functional Performance “Mill Grinding Rate” at the size of interest was the same cumulative grinding rate that is calculated from mill feed and discharge size distributions using a first-order rate equation. By calculating these cumulative grinding rates for all screen sizes, a complete ball mill model is generated (as used by Finch and Ramirez, 1981). Others in industry, Hinde and Kalala (2009), for example, have noted the same. Lacking the complexity needed to maintain their interest, most researchers have ignored this model, broadly opting instead for Epstein’s (1948) characterization of grinding as a chemical reaction, combining “selection rate” and “breakage size distribution” functions. The much simpler ball mill model presented here has previously been incorporated into a proprietary circuit modeling program (McIvor, 2005) and used for plant improvement work (for example, see McIvor and Finch, 2007, and McIvor, 2014). Now, by combining this extremely business-friendly ball mill model with optimization criteria from Functional Performance Analysis, a circuit modeling system (including the needed supplementary steps to assure successful plant implementation of circuit design changes) is at the disposal of every plant metallurgist, grinding equipment/material provider, and circuit designer."

Jan 1, 2017

By R. S. McCaffrey

In addition to its importance in agricultural production, Wisconsin is a very large manufacturing state and its rank in the metal working industries is probably first among the States of the Union per unit of population. The University of Wisconsin is a state supported institution and the Wisconsin tradition has always emphasized the relation of the University to the state and its responsibility to exercise its leader-ship where it might, in any and every way, for the development and benefit of the state and the community. The Department of Metallurgy of the University realized its responsibilities in the carrying out of the co-operative tradition and, two' years ago, an experiment was started in co-operative research between the University and certain of the industrial plants of the state. At the present time this work has so far progressed that it is no longer an experiment, and its results prove that this co-operative research may be carried on very advantageously and that, under the conditions existing in the state, the method employed has been satisfactory.

Jan 1, 1926

By S. Averill, B. Schreiner, V. Sopuck

The La Ronge. Kisseynew, Glennie Lake and Flin Flon domains. the main focu for gold exploration in the southeast part of the Saskatchewan Shield, were subject to continental glacial ice advances from the northeast during the Quaternary. Based on forty-four auger hole along with surficial mapping, the general Quaternary stratigraphy in this area is observed to be composed of a lower till unit , an overlying stratified unit of glaciofluvial sand and gravel and/or a glaciolacustrine silt-clay unit. an upper till. and an upper tratified unit. The lower till is commonly found throughout the geological domains except where it has been eroded in glaciofluvial or fluvial channels. Glacial Lake Agassiz fo rmerly covered most of these prospective domains. The lacustrine deposits associated with the lake impede surficial geochemical surveys including soil. lake sediment. and biogeochemical surveys. The approximate extent of clay cover can be predicted from beach elevations. For instance. in the Waddy Lake area. clay i not known to occur above about 1,400 feet (425 m) elevation. Exploration techniques are hampered by clay in at least one third of the volcanic belt. Thi s influence is indicated by the fact that nearly all gold prospect found to date are located above 1,400 feet (425 m) while the area of clay cover is vi rtually unexplored. The upper till i related to a minor ice readvance. This till is the medium often sampled during soil surveys in the area . lts value as a geochemical ampling medium is dependent on the extent of erosional contact with bedrock highs on the lower till. Those areas which are relatively free of lacustrine and fluvial deposits are those where surface geochemical methods work best. In the Waddy Lake volcanic belt approximately 25-50% of the area may be suitable for surficial surveys. The area of the Star Lake prospect occurs above the 1,500 foot (460 m) elevation and was not covered by Lake Agas iz. The effectivene of till sampling as a surface sampling medium was tested in those areas above the clay level. Till orientat ion surveys were carried out at the Star Lake property and the Tower Lake prospect (Waddy Lake area) within the La Ronge Domain . Gold grain counts and analy es of heavy mineral concent rate from 7 kg surface ti ll samples were used to delineate dispersion trains down-ice from mineralization. In addition, the clay fraction and a 30 g (-80 mesh) subsample from the same till sample, were analyzed for gold . In the Star Lake area, ice direction is subparallel to the strike of several narrow northeast trending auriferous structures. arrow dispersion trains down-ice from known

Jan 1, 1986

By N. Coli

The exhausted Santa Barbara open pit mine (Tuscany, Italy), owned by the main electric power company in Italy (ENEL S.p.A,) extracted lignite as a fuel for the Santa Barbara thermoelectric power plant. The mining activity led to the excavation of a wide slope (with maximum height of 200 m and a planar extension of about 1300 m x 500 m) in the Shale Limestone Chaotic Complex (SLCC) (Figure 1). Since the beginning of its excavation the slope underwent rotational landslides and diffuse instability phenomena. From a geotechnical point of view the SLCC represents a typical bimrock (block-in-matrix rock) (Medley 1994, Medley 2002, Medley 2007) characterized by a mixture of a highly sheared, scaly-fabric, clayey matrix and calcareous blocks ranging from a few millimetres to tens of metres in size. Since the geometrical properties of blocks (grain-size distribution, shape, orientation and volumetric proportion) have been proved to influence the mechanical behaviour of bimrocks (Lindquist & Goodman 1994, Goodman & Ahlgren 2000, Kim et al. 2004, Sonmez et al. 2006), the aim of the present study is to investigate the geometrical properties of calcareous blocks in order to properly characterize the mechanical behaviour of the SLCC bimrock and to further assess the stability of the slope. Block size-distribution and shape were investigated by means of advanced image analysis techniques of SLCC pictures taken in the field. Geostatistical semivariograms and variographic maps were also used in order to investigate the anisotropy of block spatial distribution. Finally, in-situ large sized sieving tests were carried out to investigate the volumetric block proportion within the clayey matrix.

May 1, 2009

By Eugene Nel, Johan Theron, Chris Martin, Hans Raabe

"Impala Platinum Limited is the world’s second largest platinum producer, producing more than 1.7 million ounces of the precious metal last year, much of this from the UG-2 reef located in the Bushveld Complex, South Africa. As part of Impala’s ongoing expansion programme, tonnage through their principal UG-2 processing facility, near Rustenburg, was increased 40% in 2001.To accommodate the increased throughput, the role of the existing primary mills was converted from conventional semi-autogenous grinding units, to attrition and selective grinding units, operating in fully autogenous mode. The finer chromite and coarser silicate components in the mill discharge are then separated by screening and processed in dedicated circuits downstream. This way, the need to spend considerable capital to increase primary grinding capacity was averted.In the last year, considerable work has been conducted to evaluate and optimise the two downstream circuits. This has involved an optimisation programme of sampling and diagnostic flotation testing, supported with QemSCAN analysis. This paper will describe the operation of the new circuit. It will also describe some of the more novel aspects and interesting findings from the optimisation programme.INTRODUCTIONThe South African platinum industry is the world’s largest producer of platinum and the world’s second largest producer of palladium. Located in a wide area north of Johannesburg, the industry mines ores from the Bushveld Complex, one of the world’s great mineral treasure chests, containing over 70 percent of the world’s platinum, as well as extensive reserves of the other PGE (platinum group elements), chrome, manganese and vanadium. The industry employs about 180,000 people in, predominantly, underground mines, which together form an almost unbroken circle of mining operations 200 km in diameter."

Jan 1, 2004