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By W. A. Lang

RESEARCH has been defined as the link between the present and the future. Science, wonderful though its achievements may be, has but scratched the surface of the unknown. Research is directing its attention to winning new facts in order that their application to the processes of today may open up new sources of wealth for the common benefit. Two classes of research investigations are often recognized-fundamental and applied, but these classes merge into each other and it is often hard to distinguish one from the other. Fundamental research is carried out primarily to develop basic facts, but frequently these are found to have immediate economic value, while applied research, specifically aimed at economic values, often necessitates a preliminary fundamental investigation. Both are essential and both should proceed by scientific method. It is obvious in fuel technology that a knowledge of the physical and chemical constitution of the various coals is fundamental to their industrial utilization, and further, a knowledge of the way these coals react under different conditions of temperature, atmosphere, etc., is necessary in solving such problems as storage, combustion, carbonization, gasification, or con-version to liquid fuels. The wide range of coals, the complexity, of their constitution, and the many uses for coal, makes fuel research no simple subject but one with unending possibilities. The Research Council of Alberta, formerly known as the Scientific and Industrial Research Council of Alberta, was established in 1919, to promote the development and conservation of the natural resources of the Province. The work of the Council was arranged in six major divisions: Fuels; Geology; Road Materials; Soils; Natural Gas; and Forest Products. The office and laboratories are located in the University of Alberta. The Council was financed until the depression of 1933 by a separate vote of the Legislature, but since then has been continued, though on a much smaller scale, as one of the activities of the University. It might, however, be noted that although the Council is now in abeyance, a skeleton organization has been maintained so that it can be brought back to active service as soon as conditions warrant. Annual reports are still submitted to the Legislature. Funds have not been made available, however, for the publication of the last five reports.

Jan 1, 1942

By The Staff

"IntroductionThis paper lists typical liner performance data for various grinding mills at the Noranda, Waite-Amulet, Pamour, and Hallnor mines, and concludes with a comparison of these data, based on wear per square foot of lined mill shell area. Flow-sheets for each of these plants will be found in the reference cited.General InformationTwenty-eight ball-mills and one rod-mill are used by the Noranda organization for grinding ore. These mills, which are shown in general outline in Plate IV, are all of the overflow type and have a cylindrical shell attached to dished heads.Most of them are serviced by hand-operated cranes and none by power cranes. During re-lining, portable tugger hoists are employed to lift the liners and, frequently, to install them in place.The mills vary in length and diameter and the ratio of end liner area to breast liner -area consequently ranges from 1. 6.75 in a 5 ft. by 14 ft. mill, to 1:2.28 in an 8 ft. by 8 ft. mill."

Jan 1, 1950

By L. Frost

"Since the late 1990s, increased prevalence of severe lung disease among US coal miners has been observed, particularly in central Appalachia where thin-seam mining is prevalent. While respirable silica exposures have been implicated in many cases, the available dust monitoring data from mines shows no explanatory trends. One possible factor could be differences in the relative toxicity of silica particles based on their surface condition. Previous research has indicated that particles with occluded surfaces (e.g., by a thin layer of clay) may be less toxic than those with non-occluded surfaces. However, this dust characteristic has not been investigated before now in central Appalachian mines. In the present study, 18 respirable dust samples from seven central Appalachian mines and two northern Appalachian mines were analyzed to assess the relative occurrence of surface-occluded silica. Results showed that the dust from central Appalachian mines actually had higher fractions of occluded silica, which may be due to extraction of large amounts of rock strata along with the coal. However, the central Appalachian mines also more silica particles overall (i.e., occluded + non-occluded) in terms of total number percentage of respirable particles.INTRODUCTIONResurgence of occupational lung disease among US coal miners, especially in the central Appalachian region, has been observed since the late 1990’s (Gibson, 2016; Zosky et al., 2016; Suarthana et al., 2011; Gamble et al., 2011; Antao et al., 2005; Attfield & Sexias, 1995). In addition to increased prevalence of simple Coal Workers’ Pneumoconiosis (CWP, or “black lung”), the prevalence of severe and rapidly progressive disease has risen dramatically (Almberg et al., 2018; Blackley et al., 2018a, 2018b, 2016, 2014; Graber et al., 2017; Cohen et al., 2016). While exposures to respirable silica have long been known to cause or play a role in diseases such as silicosis or progressive massive fibrosis (PMF), which is conventionally considered as the most advanced form of CWP, it is unclear whether silica is the only culprit in the recent outbreak of severe disease. Indeed, as disease rates have risen, both total respirable dust and silica concentrations generally appear to have declined since the late 1980s, based on regulatory monitoring data in the most affected mining districts (i.e., MSHA coal Districts 4, 5 and 12, which cover central WV, eastern KY and southwestern VA, and southern WV, respectively) (Figure 1). Of course, the latency of disease can vary and may be or more 10 years, but many of the most recent cases are likely to have resulted from exposures that occurred since the late 1980s."

Jan 1, 2019

Experimental Mine, Val d'Or, Quebec, Experiments on the ignition of sulphide dust clouds by explosives have been conducted in a 1 m3 explosion chamber. The explosives tested are ANFO, emulsion, aluminized emulsion and Detasheet. By controlling the composition of the ANFO and the emulsion explosive the oxygen balance could be changed in order to identify the dominant factors in the ignition of sulphide dust clouds by explosives. Experimental results, combined with theoretical calculations, show that the temperature of the detonation products is the most important parameter in the ignition of the dust cloud while the combustible detonation products are of secondary importance in the case of non-aluminized mining explosives. In the case of aluminized explosives and explosives having very negative oxygen balance the ignition of the dust cloud is assisted by the large amount of combustible detonation products.

Jan 1, 1993

"This generic study has been developed in response to the frequently asked question, ""That is the best treatment route for refractory gold ore?"". The study has developed operating and capital costs for many potential treatment routes and they are presented here in a generic form. All costs are in relation to the value of 1.00 given to the base case, a 1000 mtpd bio-oxidation plant, operating at 25% solids and 72 hours residence time.There is unfortunately no simple answer to the above quest ions. The treatment of refractory ores is a complex subject, with many variables, such as mineralogy, chemistry, environment and tonnage. However this study does offer information and relative numbers that we believe will be of assistance to gold metallurgists in obtaining a ""first shot"" at estimating costs.Equally, this technology is a rapidly evolving one. As more plants are commissioned, and test programs completed, better data is constantly being generated. For a generic study of this type to remain useful it will need regular updating and adjustment."

Jan 1, 1989

By D. G. Minnes

Many non-metallic minerals and structural materials are produced in Ontario to serve the needs of domestic manufacturers and export markets. In 1982 production was estimated to have a value of $765 million. Approximately 81 per cent of this was represented by structural materials, nearly 12.8 per cent by salt, and the remainder was other industrial minerals. Total mineral production in Ontario in 1982 was estimated at $3 .16 billion, down nearly $1.5 billion from 1980's high of $4.58 billion.

Jan 1, 1984

By W. D. Gould, A. Kapoor, K. Morin, P. Bédard

This paper presents the results of a research study that is being conducted by the Mine Effluents Program, Mining and Mineral Science Laboratory (MMSL), Natural Resources Canada aimed at evaluating biotechnology processes for the treatment of nitrogen compounds such as thiocyanide (CNS) and ammonia (NH4-N) which are present in gold mill effluents. A sequencing batch reactor (SBR) technology, commonly used for the biological treatment of municipal and industrial effluents, was used in this study. In the SBR process, the micro-organisms were able to degrade CNS to NH4-N and NH4-N to nitrate (NO3-N) at operating conditions of two 12 h treatment cycles per day, with pH maintained in the 7.4 to 7.6 range, and at room temperature (approximately 21°C) and also at 12 °C. The end products of CNS and NH4-N biological oxidation were NO3-N and sulphate (SO4) that are relatively non-toxic. Partial removal of NO3-N was achieved by biological denitrification reactions in the SBR process. The SBR process effluent was measured to be non-toxic to rainbow trout based on the 96 h acute toxicity test. The microbial consortium isolated from the SBR treating a simulated effluent was able to effectively oxidize CNS and NH4-N to NO3-N in water samples (under batch conditions) collected at three mine sites located in Quebec, the Northwest Territories, and Yukon.

Jan 1, 2004

By J. R. Goode

"Coarse ore sorting is here defined as the physical separation of a mixture of coarse (+3/8 inch) ore particles into two or more separate groups of total value greater than that of the unsorted ore. An ore will probably be sortable if the geology of the orebody and the mining practices employed meet conditions outlined in this paper.The paper points out how sorting can substantially reduce tonnage variable operating costs because sorting can double the mill head grade of amenable ores by rejecting waste rock from the mine output. The effect of sorting on ore reserves is outlined. It is also suggested that sorting is a low cost alternative to conventional expansion.The mode of operation of the Ore Sorters Kadel 13 Photometric and MK VI A Radiometric sorters is detailed. The report concludes with detailed descriptions of the photometric sorting plant operated by the Doornfontein Gold Mining Company is South Africa and the Radiometric Sorting Plant presently under construction at the Schwartzwalder mine of Cotter Corporation in Colorado."

Jan 1, 1975

By D. Mark Richards

Highland Valley Copper (HVC) is a large open pit copper mine in the southern interior of British Columbia. Machine guidance technology using GPS has been utilized at the mine since 1996 for blast hole drill navigation and since 2000 for shovel and dozer navigation. Since 1997, rock recognition has been part of the drilling process. This allowed the mine to develop a Mine to Mill strategy using the rock hardness information from drill monitoring systems to both refine drilling and blasting parameters as well as downstream crushing and grinding strategies. Although this preliminary effort has been very successful at HVC, the current intent is to gain further benefits through better use of existing information while also deriving an enhanced data set from monitoring production drills. In the latter case, the objective is to acquire and process drill variables in such a manner as to permit more detailed definition of rock mass characteristics. The subsequent focus will be to use the derived geotechnical and geological information as part of a practical process to more prescriptively blast the rock mass. Through the definition of domains based on drill monitored derived rock mass properties, the intent will be to enhance blast outcomes that lead to optimized downstream (from blasting through to concentration) processes in a more proactive and timely manner. This paper examines a proposed approach to be able to derive more accurate and consistent rock mass properties from production drilling. In addition, the discussion will identify potential benefits to be gained from process improvements that result in enhanced productivities, and crushing and grinding optimisation due to blasting strategies that are more closely matched to identify rock mass characteristics.

May 1, 2007

By Charles A. Taschereau

Burkina Faso ? Formerly known as Upper Volta; Country is landlocked and dry (Sahel sub-Sahara zone); ? Among poorest countries in the World, according to the United Nations Human Development Index (in 2005, 178 out of 179 countries; in 2009 173 out of 179); ? Population 13,9 Millions; Life expectancy is 51.4 years; Fertility rate 6.47 children/woman; Average age is16 years; literacy rate 23.6% and GDP per capita $1,213; ? French is official language; Politically stable country; very low criminality rate; corruption level low. Multiparty elections since early 90s; Legal and political systembased on French civil law system; ? Country just opened a few years ago to International mining companies, with a new mining code and investment code; ? No experienced labour; ? All new codes and laws; no established practices; Very limited economic development, mining is already main product of exportation and the country will become with Essakane a mineral economy (over 50% of total exports from mineral sources);

May 1, 2010

By C. J. A. Davie

"SUMMARY A practical application of nitric acid oxidation of sulphides, based on the principles of the Arseno process, has been developed for the Cinola ore. Development of the process has been based on testwork conducted by Bacon Donaldson of Vancouver and Hazen Research of Denver, and on conceptual engineering performed by Minproc Engineers of Denver.A comprehensive Stage II report for the project has been submitted to the B.C. permitting agencies, containing provisions for a zero discharge tailings impoundment system and prevention of acid mine drainage. Approval in principle is expected in early 1989.A feasibility study recently completed by Minproc Engineers and Davy McKee Corporation demonstrates that this project can be brought to production for a capital expenditure of C$120 million for a mill throughput of 6,000 tonnes/day and operated at a total direct operating cost of less than $20/tonne.INTRODUCTION The Cinola orebody was discovered in 1970. It is situated approximately in the centre of Graham Island, the largest of the Queen Charlotte Islands. It represents the mid to upper levels of a hydrothermal precious metals system, characterized by intense brecciation and silicification. Gold is associated with finely disseminated sulphides in a breccia matrix and in free form in numerous quartz veins.Ownership of the property has changed hands a number of times, and previous attempts to bring the property to production have failed. Two critical factors have frequently been blamed for difficulty in creating a successful project: namely, process and environment factors, hence the title of this paper.City Resources (Canada) Limited (""City"") acquired the property in 1986, and commenced an aggressive campaign to verify ore reserves, to carry out metallurgical research and to address environmental issues.PROJECT OVERVIEW When the Cinola orebody was discovered, the significance of hydrothermal mineraliza¬tion associated with crustal plate boundaries was not recognized, and for several years, the orebody was considered an uneconomic curiosity. If the type and location of orebody sought by many companies engaged in gold exploration were to be specified, it would probably be a description of the Cinola orebody - it is a large (greater than 1.5 million ounce), low grade (2.45 gm/tonne), refractory ore reserve associated with the Pacific rim crustal plate boundary. The industry appears to have recognized in the past few years that its future lies in the exploitation of such orebodies, and is prepared to come to grips with the technical problems associated with such ores. In this sense, the Cinola orebody might be considered to have come of age."

Jan 1, 1989

By H. R. Banks

"AbstractThe rod mill introduced into the Sullivan Concentrator flow in September, 1948, replaced two sets of 74 in. by 20 in. rolls and their accompanying screens. In addition to the work formerly done by the rolls, the rod mill is producing a finer product and one which provides more suitable feed for the primary ball mills. The object of the finer discharge from the •primary mills is to make possible a feed directly from the mills to a series of flotation machines where a large portion of the galena can be withdrawn from the circuit while the galena is still coarsely granular. The interposing of classifiers between grinding and flotation means the selective grinding of the galena.The author summarizes the work of •the rod mill through the first 5,000,000 tons and shows that the wear of lifters, liners, and rods is definitely below normal for the type and size of rock being handled. The rod mill, driven through a fluid coupling, has been subject to a range of speeds from 13.5 to 19. A pinion in the speed reducer was changed to allow the extending of the normal speed range of the fluid drive of approximately 4 r.p.m.Since the critical speed inside the liners •is 23.4, the range •in per cent of criticial is 57.7 to 81.2 per cent.The capacity of the mill increases with increasing speed but the character of the product remains approximately the same except when the feed rate is too high.Consumption of steel, power, and other operating data are presented.The author introduces certain fundamental observations on the principles involved •in comminution in order to support the special design and operation of the rod mill."

Jan 1, 1952

By Mike Rylatt

"The BHP Diamonds Inc. and Blackwater Group (Dia Met Minerals Ltd., Charles Fipke and Stewart Blusson) joint venture began production at Canada=s first diamond mine during the last quarter of 1998.Construction of the processing plant began in mid 1997. During the 1998 winter season, the heavy process plant equipment was delivered to the Ekati site, 300 km NE of Yellowknife, by the ice road. Towards mid 1998 the construction activities were complete and commissioning began. The mine officially opened in October 1998.Initial production of 9000 tpd kimberlite will be from the Panda pipe grading 1.09 ct/t at an average value of US$13O/ct.Processing starts with a gyratory crusher reducing the ROM kimberlite to 90% passing 15Omm before further reduction to minus 75mm in a WaterFlush crusher. The crusher product discharges into a 4m diameter x 7m long primary scrubber. After screening, the minus 75 +1 mm kimberlite is conveyed to a 250 ft feed bin ahead of the 1.7 m diameter x 1.1 m wide high pressure grinding roll. The HPGR produces 50% minus lmm in a single pass, the compacted flake product is dis-agglomerated in a secondary scrubber. The scrubber product is screened into a minus 25 +lmm heavy medium separation plant feed and conveyed to a 375t HMS feed bin ahead of two 150 HMS modules. Milled 270D ferrosilicon at a slurry density of 2.6 g/cc and HMS feed are pumped to three 420mm diameter cyclones. Heavy mineral concentrates, approximately 1 % of the plant headfeed, are pneumatically transported to the Recovery plant for final diamond recovery using wet high intensity magnetic separators and high intensity (attrition) milling prior to three stages of x-ray recovery. At full production, Ekati will produce approximately 2 kg/day of diamonds.This paper details the later commissioning phase and the first three months Oof operational activities during the build up to full production at the Ekati processing plant."

Jan 1, 1999

By S. P. Singh

"The geological features of a rock mass have a direct influence on its blasting characteristics. It has been observed that perimeter control techniques provide excellent results in massive crystalline formations but may give poor results in weak and or highly jointed formations.A field study was conducted with the objective of understanding the role played by the geological features of a rock mass in producing and controlling blast damage. The field work involved the assessment of blast damage at several operating mines and the blasting of drift rounds in a geologically dominant rock mass.The effect of rock strength, rock quality designation (RQD), joint parameters and hydrogeological conditions on blast damage is described below. The influence of number and thickness of weak layers on blast damage is also discussed below on the basis of quantitative data. In addition, critical particle velocity ranges for damage to different rock types have also been outlined in this paper."

Jan 1, 2001

By A. B. Cron, R. MacPhail, L. Melis, K. Armstong

"Mt. Milligan is a porphyry gold/copper deposit in north-central British Columbia. Diluted and mineable drill-indicated reserves total 449 million tons at an average grade of 0.013 oz gold/ton and 0.19% copper. Large-scale commercial development of the deposit will make Mt. Milligan Canada's third largest gold mine.Metallurgical investigations for the Mt. Milligan project were done in three phases: scoping tests in the first half of 1989; bench-scale work from October 1989 to April 1990; and a pilot plant program in May and June 1990. Various process alternatives for the recovery of gold and copper are described and results are presented. Net smelter return evaluations led to the selection of optimum process conditions for maximizing revenue from gold/copper flotation concentrates.The selected flotation circuit and basic design criteria are described. Forecast average recoveries over the presently-defined 20-year project life are 75.2% for gold and 90.5% for copper in a copper concentrate averaging 17.6% copper and 1.0 oz gold/ton. 1.0 PROJECT LOCATIONThe Mt. Milligan porphyry gold/copper deposit is located in northcentral British Columbia, 150 km north of Prince George, British Columbia. The site is at an elevation of 1,100 m in an area of logged, gently-rolling topography. Nearby communities include MacKenzie and Fort St. James. Climate in the area is moderate and there is direct road access to the property. A location map is presented in Figure 1-1."

Jan 1, 1991

By Dan Marshall, David H. Watkinson

Abstract - Cobalt, Ontario, is renowned for the 12.6 billion grams (445 million ounces) of silver produced from the area since discovery in 1903 by workers of the Timiskaming and Northern Ontario Railway. Native silver generally occurs with cobalt arsenides and sulfosalts in near-vertical carbonate veins cutting the Huronian sedimentary rocks of the Gowganda Formation, the Archean metavolcanics and/or the Nipissing diabase. All major deposits have been found within a few hundred meters of the unconformity between the Archean and Huronian rocks in general proximity to the Nipissing diabase and volcanogenic sulfide mounds within the Archean meta-volcanics. Silver has been mobilized from one or more of the local country rocks by hyper-saline brines and deposited in or near zones of mixing where the saline brines encounter paleometeoric water transported to depth along the unconformity or local structures. Previous work has shown that chloride complexes are the dominant ligands responsible for silver transport. These hypersaline brines, represented as halite-bearing fluid inclusions at room temperature, have been trapped as primary fluid inclusions within vein minerals. Pressure-temperature conditions of vein formation have been derived from mineral equilibria, maximum lithostat and fluid-inclusion studies. These data are consistent with vein formation occurring over the temperature range 300°C to 350°C, with pressures constrained between 60 Mpa and 136 Mpa (600 bars and 1360 bars).

Jan 1, 2000

By C. Larsen, D. Fragomeni, A. Vien, D. G. Fisher

"MOCCA is a Multivariable Optimal Constrained Control Algorithm developed specifically for non-square industrial control applications with practical difficulties such as interactions, time delays, constraints, modelling errors, etc. MOCCA consists of an off-line simulation/translation module, for tuning the control parameters, and an on-line module that implements the designed control law.This paper describes an evaluation of MOCCA on the Hemlo grinding circuit which comprises one open circuit ball mill and two closed circuit ball mills in series. In this case a 4x4 unconstrained control problem was considered. The manipulated variables included the fresh ore feed rate and three pump box water additions. The controlled variables were the grinding circuit product particle size and three pump box levels. In this application soft constraints were implemented through control action and control error weighting. The feedforward capability of MOCCA was used to compensate for a measured water flow disturbance to one of the pump boxes. MOCCA performed very well during plant evaluations when compared to the original classical multi-loop control strategy and proved to be quite robust. Perhaps most importantly, the process engineers and plant operators have a high level of comfort both in understanding MOCCA's general operating principles, and with its demonstrated performance."

Jan 1, 1991

By Nessetech Consulting, L. A. Cisternas, E. D. Galvez, S. H. Kuan, L. H. Saw

"In Malaysia, there were two rare earths processing plants namely Asian Rare Earth (ARE) and the Malaysian Rare Earth Corporation Plant (MAREC) in Perak, which were operated until 1992 and were subsequently closed due to problems pertaining to disposal of large amount of radioactive waste. Recently, Lynas Advanced Materials Plant (LAMP) has become one of the largest rare earths processing plant in the world producing rare earth elements (REE) in Gebeng, Pahang. The primary raw material is lanthanide concentrate (LC) which is imported from Mount Weld mine in Australia and shipped to Malaysia. LC is produced from lanthanide ore after mining and mineral processing. The ore has a lower impact than Bayan Obo, Mountain Pass and adsorbed clay deposits, given the small footprint of the mine itself and the remoteness of the location. The type of ore being mined (rare earth phosphates: carbonatite, monazite) may have higher thorium content than bastnasite ore from the Chinese or American mines but still far below radiation concerns. This paper was written to review the processing flowsheet at the Lynas Advanced Materials Plant (LAMP), the environmental impact associated with the processing of the said ores and the sustainability of the operation.INTRODUCTIONRare earth minerals are one of a set of 17 minerals or chemical elements which consists of yttrium and scandium, as well as the 15 lanthanide elements (lanthanum, cerium, praseodymium, neodymium, promethium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, and lutetium). Despite their importance, rare earth minerals rarely exist in economically viable concentrations and they are usually difficult to extract. Rare-earth minerals create strong magnets when added to magnetic elements such as iron, and are useful for the production of electronics systems as well as electric cars. They are also used extensively in automotive catalytic converters, fluid cracking catalysts in petroleum refining, wind turbines, phosphors in colour televisions and flat panel screens, displays for mobile phones and laptops, rechargeable batteries, and various medical devices. The elements are typically split into two subgroups: the cerium sub-group of ‘‘Light’’ rare earth elements (LREEs) which includes La to Eu and the yttrium sub-group of ‘‘Heavy’’ rare earth elements (HREEs) which include the remaining lanthanide elements, Gd to Lu, including yttrium (Gupta and Krishnamurthy, 1992; Jordens et al., 2013; Trifonov, 1963). Scandium, however, when it is classified as a rare earth element, is not included in either the LREE or HREE classifications (Gupta and Krishnamurthy, 1992; Jordens et al, 2013). Half of the world’s 110 million tons of reserves exist in China while other sizable deposits are found in Russia, United States, Brazil, India, Australia, Canada, and Greenland. The countries known to be actively mining REE are China, Russia, India, Brazil and Malaysia (Hao et al., 2015). Among these countries, China has the largest REE production, accounting for more than 93% of global supply (Yap, 2015). The critical metal report (Moss et al. 2011) listed 14 economically vital raw materials that are prone to supply disruption and concluded that supply disruption would threaten the goal for cleaner transport and sustainable energy since rare earth metals are used in products using green technology, such as hybrid/electric vehicles, carbon capture systems, wind power generation, low-energy lighting, and energy efficient flat-screen displays."

Jan 1, 2016

By André van Wageningen

Since the beginning of this century Boliden Mineral and Atlas Copco have worked together in stages on improving the accuracy and quality of drilling. Navigation of the drill rigs with IREDES has been in use in the Boliden mines for several years. Recently the capability of the system has extended with map navigation to more accurately follow the ore in cut&fill mines. The system allows for changes on the individual round level to follow the ore without changing the whole design for the heading. Those changes are done in a CAD-system and remove the need for face markings and will allow for even better accuracy in both height and wall position. All the information between the CAD-system and the drill rigs is exchanged using the IREDES standard. This paper describes the workflow and the use of the IREDES standard.

Oct 1, 2009

By Peter Mitschke, Friedrich Rosenstock, Heinrich Meiler

"The development of the Centrifugal Mill jointly by Chamber of Mines (Johannesburg) and LURGI GMBH (Frankfurt) had been described by L. Kitschen e.al. during the 14th IMPC at Toronto in October 1982. Further investigations, using a 55 kW semi-industrial mill, installed at LURGI's Research Laboratories, were concentrated on efficiency and wear in grinding.The test results showed, that efficiency increases when increasing the ball load between 60 and 80 % by volume. Furthermore, the efficiency is increased by speeding up the mill, thus increasing the centrifugal force to up to 14 times the force of gravity. Applying these findings to grinding of a Canadian iron ore spiral concentrate, a saving in grinding power of 30 % was experienced, when comparing with ordinary wet ball milling.Investigations of several shapes of the grinding chamber cross section and linings and several types of materials showed, that no increase of liner or ball wear will occur compared to conventional ball mills when choosing suitable lining patterns. 1. DEVELOPMENT OF THE CENTRIPUGAL MILLThe centrifugal mill was developed with the aim of finding a grinding unit that can operate at a higher power concentration than the conventional tumbling mills.LURGI felt the necessity for such a mill in connection with a hydrometallurgical process developed at the beginning of the seventies, which incorporated an activating grinding step as one of the essential process features. At that time, the Chamber of Mines in Johannesburg was investigating possibilities of underground wet grinding and preconcentration of gold ores aiming at a decrease of mining costs by reducing the quantities, especially for mines operating at depths up to 3600 m, by changing over from rope hoisting to hydraulic transportation systems. After the Chamber of Mines had initiated the development work on its own, in 1974 a cooperation between the two organisations was started."

Jan 1, 1985