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By Edward Hart

The specimen of glazy iron used for analysis was highly characteristic in appearance. It was made at one of the furnaces of the Glendon Iron Works, working a light burden of ore with a highly silicious cinder. There are very few records of analyses of this variety of iron. I have been able to find but the two given by Bell, and I add these to my analysis for comparison. Bell. 1. 2. Iron,......89.47* 88.18 90.70 Carbon, combined,.... 0.00 0.79 0.71 Graphite,......2.88 2.59 2 68 Silicon,......5.47 5 13 5.13 Manganese,.....1.54 0.77 0.56 Sulphur,......0.04 0.17 0.23 Phosphorus,.....0.60 1.12 1.12 Titanium,.....- 0.26 0.18 Calcium,......0.00 0.22 0.20 Magnesium,.....0.00 0.06 0.03 100.00 9929 101.54

By A. E. Aho

"The material presented in this paper will be subject to modification as new data become available, but it is presented in the hope that it will inspire more intensive mineral exploration and geologic studies of what appears to be one of Canada's richest mineral provinces. A metallogenic province 400 by 150 miles in extent, lying mostly northeast of Tintina trench, encompasses most of the base metal deposits of Yukon, as well as deposits of other metals. Its main features are northwesterly trending arcuate fold belts, with several orogenic axes, which include most of the metamorphosed rocks, granitic intrusives and mineralization; and which are modified by regional uplifts, northwest-striking fault trenches, and lesser transverse folding and faulting.The main base metal occurrences and their regional controls are summarized briefly. Most of the replacement-type deposits are localized in late Proterozoic to early Paleozoic rocks, particularly Lower Cambrian -probably because these are the most physically and chemically favourable hosts encountered in an appropriate temperature and pressure environment; perhaps because of early age of deposition. Most of the deposits also occur near heat sources or intrusives with associated structural uplift, which has, moreover, served to expose the older rocks. They also tend to occur near known or suspected regional fault trenches, such as Tintina, Macmillan and Hess, although this relationship may be fortuitous. In detail, they may be localized in fold axes, flat-lying beds or other appropriate structural traps. Vein-type deposits are fracture-controlled and localized by dilational localfties, the competence of wall rocks and ""damming"" effects.In the Anvil district, large stratiform iron-zinc-lead replacement deposits lie parallel to gently plunging flex-ures in phyllite in a zone parallel to the Tintina trench, along the southwest flank of the arch-like Anvil batholith. About 80 million tons of massive sulphide ore probably existed before erosion of the Faro orebody, the Vangorda deposit could have been of similar magnitude before erosion and much more tonnage probably remains to be discovered in the district. The Anvil deposits may differ from others found to date in Yukon, but resemble the Sullivan orebody of southeastern British Columbia in their large size, localization in essentially non-limy peptic to arena-ceous host rocks of Proterozoic or early Paleozoic age and proximity to the Rocky Mountain -Tintina trench sys-tem. These features suggest an origin from primordial subcrustal sources.More major ore deposits, not only of lead, zinc and copper but probably of other metals as well, will no doubt be found in similar environments in Yukon or Alaska. Thus, the base metal province of Yukon offers challenging opportunities for prospecting, development, field studies and basic research."

Jan 1, 1969

"IntroductionIn the 1970s, environmental concerns and associated liabilities were a new and unknown aspect of corporate risk. Today, social concerns and the associated conflicts that they can generate constitute a rapidly expanding aspect of risk. Although not a new phenomena — the Bougainville copper mine was forced into closure in 1988 — social risk has emerged as considerably more important, and increasingly visible, in the last few years. Social risk is now an aspect of all mining activities which needs to be calculated into project assessments, and to be managed throughout the life of a project. While social risk has a number of aspects at the corporate level, such as company image and shareholder relations, at the level of the individual project, its primary component is social acceptability, and the principal tool for managing it is the Social Licence to Operate.Social Risk in Latin AmericaThroughout Latin America there are newly modernized mineral codes and economic systems introduced over the last ten years which, together with new environmental legislation, look very much like regulations in developed countries. To the corporations, the existence of these instruments means that the risks from the environmental issues associated with the project are known; they are legislated, defined, quantifiable and hence manageable.It seems ironic that, just when comprehensive regulations for the environmental management of mining have been put in place throughout Latin America, there arise an increasing number of challenges to mining activities. For, in spite of the apparent guarantees provided by these new legislative reforms, communities in Latin America today are more frequently standing up and taking exception to the presence of mining companies, or the ways in which the companies are conducting themselves. The viability of projects becomes threatened because they are considered socially unacceptable, a phenomenon that we describe as social risk. These challenges are less about opposing mining activities than many people would think. Rather, they are based on an increasing desire on the part of the local population to have some measure of control over their own future, and to participate in the development process from the earliest stages."

Jan 1, 2000

By David Heydon

NAUTILUS MINERALS is a leader in the commercial exploration for and evaluation of seafloor massive sulfide (?SMS?) deposits. Nautilus has exploration licences covering 15,000 sq km of seafloor in Papua New Guinea and is evaluating other areas in the Western Pacific. The Nautilus Western Pacific Gold-Copper project is an interesting case study of the interaction of the disciplines of Science, Engineering and Environmental Science to solve and attend to the challenges of a project without precedence. The Science books of geology and marine biology with respect to seafloor massive sulfides are still being written or at best are thin volumes with recognition still we know very little at this time. Science?s early discoveries and study of these mineral processes on the seafloor provided invaluable data from which to develop an exploration strategy and the genesis of Nautilus itself. The Engineering required for development of such deposits is a combination of yet to be tested ?theory and engineering principles? and adaptation of best practice from other fields such as oil/gas and telecommunication cable laying. The Environmental guidelines for exploring these deposits, let alone mining them, is at the moment still being debated by a panel of experts chosen by the International Seabed Authority.

Jan 1, 2005

By Richard L. Gordon

Coal supply analysis has since about 1973 become a major activity of many scholars and consulting firms. The present paper is an effort to explain in as nontechnical fashion as possible the state of the art and what implications, if any, the research has for those actually engaged in producing coal or regulating the industry. l The discussion stresses the coal supply side of the models and makes limited comments about other elements in the analysis. To orient the appraisal, it is desirable to recall the features of coal supply that an adequate model should capture. The first considerations are the locational aspects of the industry. Transportation costs can, in some cases, exceed the production costs of coal, and thus any adequate model must incorporate a treatment of the economics of transporting coal from one location to another. A second major issue is that of the heterogeneity of coal; models should treat as well as possible such key differences among coals as their Btu and sulfur content. Third, we recognize that, with given technology and labor, capital, and supply costs, an expansion of the supply of a given type of coal in a specific region will occur only if prices rise. This is the familiar proposition of textbook economics that supply is an increasing function of price. Finally, over time, changes in technology, input cost, and depletion interact to cause changes in the price of given amounts of coal. Economics represents the net effect of this process by a shift over time in the supply curve. During the 1950s and 1960s, the trend was to reduce the production costs of a given output; subsequently costs rose sharply.

Jan 1, 1977

By Javier Illanes, Felipe Moroni

In recent years, implementation of Artificial Intelligence and Machine Learning model technology has gained ground in almost every aspect of human activities. The mining industry has not been foreign to these applications, with advantages including the creation of new optimization methods and the elimination of repetitive tasks. Those applications have been implemented in multiple operative areas, from preventive conveyor belt maintenance to energy optimization for minimizing environmental impact. The blasting process aims to use the energy liberated by the detonation of explosives to break the rock mass according to specifications that facilitate the comminution process. To optimize this process, the energy delivered must correspond to the necessary amount to exceed the tensional and compressional resistance of the rock mass. If the energy applied is insufficient, the rock will not reach the desired fragmentation level and the processing plant may incur additional costs. On the other hand, if the energy level required is exceeded, we incur increased blasting costs that correspond to excess explosive used. Optimization of this aspect of the mining process has major impact in the processing chain reflected in lower costs, efficient resources consumption and environmental impact. The Design for Outcome technology (DfO), developed by Orica, is used to characterize the rock mass in detail to classify, borehole by borehole, the rock mass relative hardness to deliver the adequate energy level to achieve optimal fragmentation. This technology uses information collected by drill sensors, producing data typically referred to as Measure While Drilling (MWD) data to classify the rock mass into domains that can later be used to apply optimal blast designs. In DfO, the data flow is fully automated, starting with the data produced by the drilling system and uploaded to the cloud, which is then domained using Machine Learning (ML) techniques, and then published for consumption using a web interface. Automated explosives loading rules are then generated for each rock mass domain, ensuring that for each borehole, the adequate explosive energy is delivered to achieve the desired fragmentation results with unprecedented accuracy. The application of machine learning techniques allows us to optimize the blasting process results by leveraging a deeper understanding of the rock mass. Applying these optimization techniques, we obtain considerable economic benefits, decrease resources consumption, and achieve a more sustainable mining operation. The application of DfO in a Chilean mining operation allowed the characterization of their rock mass into four domains and established specific explosive loading rules for each one. A 60kUSD reduction in explosives cost was achieved during the test period, while maintaining the desired fragmentation results and expected dig rate. These outcomes were the result of a comparison between the blasting costs used applying the technology mentioned above and a “traditional” classification of the rock mass with the corresponding blasting practices.

Jan 21, 2025

By X Hu, Z Pokrajcic, R Embry, P C. Stewart, J Carpenter, E Jones

Whilst the value of Pit to Plant and Mine to Mill optimisation has been proven since the 1990s, sustaining the productivity and efficiency gains typically requires ongoing test work, blast trials, plant surveys, and model calibration services. In contrast, the input to digital twin Pit to Plant or Mine to Mill optimisation is tens to hundreds of millions of tonnes of standard mine operating data. This paper presents a series of digital twin case studies from across the mine value chain, including machine learning testing methodology, model accuracy statistics and the application of Shapley Additive Explanations (SHAP) for model interpretation. These case studies demonstrate how machine learning and data fusion ore tracking connects hundreds of millions of tonnes of downstream performance data to produce digital twin models (operating models that are continuously updated and integrated into the wider Mine to Mill/Pit to Plant ore tracking system). Digital twin modelling software has been used to add block model variables for dig-rate, crusher and mill throughput, recovery (tailings grade), lump yield, product grade and product quality, fines yield and fines in lump. Block-by-block predictions are added to the geological resource and grade control block models as new block model variables. These new block model variables are used across all mine planning time horizons from life-of-mine planning to daily schedules. In addition to the materials handling and geometallurgical prediction case studies, the paper also presents digital twin case studies for drill and blast simulation and plant set point optimisation. The case studies show how digital twin simulation enables drill and blast engineers to simulate the effect of different blast designs in different blast domains using the mines operating data. Plant set point optimisation applies mathematical optimisation algorithms to the machine learning model to provide live operational decision support to metallurgists and plant operators. The digital twin machine learning case studies demonstrate a digital and sustainable paradigm for Mine to Mill and Pit to Plant optimisation.

Jun 22, 2022

By Adam Levy, Thomas Novak, Sampurna Arya, Joseph Sottile, Kozo Saito

The use of a woven wire-mesh screen as part of a flooded-bed dust-scrubbing system is popular in the underground coal mining industry. It is used in combination with a demister (mist eliminator) to remove dust from the dust-laden air. A study was conducted to measure the pressure drop across a flooded-bed, wire-mesh screen at different airflow rates in one-phase (dry) and two-phase (wet) conditions. Two empirical relationships between pressure drop and air velocity were developed for dry and wet conditions, respectively. In both cases, the form of the empirical relationships was found to be similar to relationships given by Sabri Ergun for high velocity, non-Darcy, single- and multi-phase flow through porous media. The experiments were repeated on a reduced-scale model of the wire-mesh screen, and the pressure-velocity relationships obtained from the full-scale prototype experiments were tested. The test results show validation of the full-scale empirical formulae on the small-scale model with an insignificant variation. This paper presents the empirical equations for pressure drop across the wire-mesh screen in dry and wet conditions. Researchers can use these equations as a tool to predict total pressure drops for wire-mesh screens of different scale sizes.

By L. C. Graton

[CONTENTS PAGE INTRODUCTION AND ACKNOWLEDGMENTS. By George M. Fowler2 Question 1-Is Structural Deformation of Some Character Always Necessary for the Migration of Mineralizing Solutions, Especially in Limestone or Other Dense Rock? DISCUSSION by: A. M. Bateman 10 S. F. Kelly 15 C. H. Behre, Jr 8, 13 G. B. Langford 13 T. M. Broderick11 H. E. McKinstry6 R. H. Clarke 13 D. H. McLaughlin8 J. D. Forrester for M. H. Gidel . . . 4 W. H. Newhouse13 G. M. Fowler 2, 6, 11 R. H. Sales 6 L. C. Graton 11 Edward Sampson 12 R. D. Hoffman 10 J. S. Stevenson 7 I. B. Joralemon11 L. B. Wright 2 Question 2-What Are Some of the Chemical and Physical Characteristics in Certain Beds within a Limestone Formation that Determine Their Favorable or Unfavorable Aspects as Reservoirs for Ore and Other Introduced Minerals? DISCUSSION by: G. W. Bain 17G. M. Fowler 21 C. H. Behre, Jr21L. C. Graton18 J. S. Brown 16G. F. Loughlin18 E. L. Bruce 19R. H. Sales 19 R. H. Clarke 20A. K. Snelgrove 20 Question 3-Are There Any Criteria by Which One Can Determine When Mining Operations Have Reached the Roots of an Ore Deposit? DISCUSSION by: J. M. Boutwell29G. B. Langford 29 T. M. Broderick28G. F. Loughlin25 E. Y. Dougherty27R. H. Sales 24 G. M. Fowler 22F. A. Thomson 26 I. B. Joralemon 22Edward Wisser 30 General S. F. Kelly35 References36

Jan 1, 1940

By K. K. Kershner

This report describes an investigation by the Bureau of Mines designed to provide background data for extending and improving the applications of chlorine metallurgy in extracting metals from ores. Optimum conditions are given tor chloridizing galena, sphalerite, and chalcocite by contact with chlorine gas. Petrographic and chemical analyses of the sulfides used in the experiments are listed. Graphs are furnished showing the extent of chloridization of each metal sulfide over the temperature range of the observations. In each case, the first tests were made with the reaction chamber at room temperature. This temperature was increased by regular increments in succeeding tests until the temperature was reached at which quantitative conversion of the sulfide to chloride was observed. The data are also plotted for screen-size fractions of the sulfide minerals investigated. Data show that the extent of metal chloride formation was affected by chloridization time, particle size of the sample, and usually, the temperature of the reaction chamber. At 300° to 400° C. an anomaly was noted for both galena and sphalerite. The temperature at which this anomaly was observed varied according to the particle size of the mineral. Comparisons are made between the chloridizing characteristics of the mineral sulfides and their chemically prepared counterparts.

Jan 1, 1961

By Arthur L. Crawford

PLAGER gold is perhaps the most difficult of the common mineral deposits to evaluate. Not only are the erratic pay streaks a source of never-ending uncertainty, but the spotty distribution of the gold in iso¬lated nuggets is a perpetual source of error and disappointment to the sampler. Experienced engineers have long realized this difficulty and have been wary in predicting assay values except in the most general terms, and then only after extensive and usually expensive sampling. During the past year I have had the opportunity of checking a number of gold placers, and from the results obtained I believe that the microscope may be employed to advantage in placer sampling.

Jan 1, 1933

By J. C. White

"During the early development of the Mattabi Mine in 1970, discussions with the Ontario Government revealed their policy of prohibiting, as much as possible, the development of new, isolated, single-industry townsites. Subsequently, Mattabi located its first housing in the Township of Ignace, which is situated 50 miles from the site of the mine and plant. Over 200 employees now commute 100 miles daily to and from work.This paper describes the experience gained and discusses the advantages and disadvantages of a remote townsite."

Jan 1, 1976

By Benjamin W. Haynes

The Bureau of Mines, in cooperation with the National Oceanic and Atmospheric Administration (NOAA), has updated a 1977 NOAA report prepared by Dames & Moore entitled, "Description of Manganese Nodule Processing Activities for Environmental Studies." This updated report contains detailed flowsheets and descriptions of the five potential first-generation nodule recovery schemes now considered most likely to be used by industry; they are high-temperature gas reduction and ammoniacal leach, Cuprion ammoniacal leach, high-temperature and high-pressure H2S04 leach, reduction and HCI leach, and smelting and H2S04 leach. The first three processes are three-metal recovery schemes (Cu, Ni, and Co) with the option of Mn recovery from the tailings. The remaining two processes are four-metal (Cu, Ni, Co, and Mn) recovery schemes. All except the HCI process are assumed to use a nodule feed rate of 3 million tons per year (dry basis). Final metal products are Co powder and cathode Cu and Ni. A minor amount of Ni is also recovered as powder, and some Cu and Zn are recovered as mixed sulfides. Manganese in the four-metal processes is recovered as either manganese metal or ferromanganese.

Jan 1, 1983

By Paul L. Russell

THIS is a progress report of an experiment being undertaken in cooperation with the Bethlehem Steel Corp., the Crucible Steel Co., and the Rock Bit Sales and Service Co., involving heat treatment of the shank ends of drill steel. This experiment is being conducted by the U. S. Bureau of Mines in its experimental mine, Mining Research Branch, Bluemont, Va. The purpose of the experiment is to determine the effect of an increase in the time the steel soaks in the furnace during the hardening heat. It has been thought that increasing this time produces a soft zone below the lugs resulting in a metallurgical notch that causes early failure. Each of the steel companies furnished enough 11/4 - in. straight carbon, hollow, round steel to make up 10 sets of drill steel, in each instance the steel bars were from the same heat. These sets of drill steel, consisting of 2-ft, 4-ft, 6-ft, and 8-ft lengths were fabricated by the Rock Bit Sales and Service Co. Special attention was given to the forging of the steel to produce the best rods possible. The heat treatment of all thread ends was identical and followed the best practice. The heat treatment of the shank ends of five sets of steel from each company produced a soft zone 2 to 4 in. in front of the lugs. It was decided that possibly the best way to obtain this effect was not to overlap the hardening heat but to let the steel soak for an additional 30 min before quenching. Therefore the only variable in the test steels is the length of time the shank ends were in the furnace. The remaining drill steel shanks were treated as follows: Heat treatment in pyrometer-controlled furnace at 1550°F. Quenching oil at 105°F to 125°F temperature. Areas for heat treatment were; shanks, 11 in.; threads, 9 in. Time at heat, standard practice, 20 min for 11/4-in. steel. Actual drilling tests were made in greenstone, (a metamorphosed basaltic rock), and in epidosite. Greenstone has a specific gravity of 2.96 and a compressive strength of 44,200 psi. Epidosite has a specific gravity of 3.26 and a compressive strength of 63,100 psi. All drilling tests were made using a 31/2-in. column-mounted, automatic feed drifter, with a controlled air pressure of 90 psi at the throttle. Tungsten-carbide bits of 2 in. diameter were used for all drilling. Contrary to expectations the drill steels that were allowed to soak for the additional 30 min before quenching performed better than the steels that were heat treated according to standard practice. This performance, as shown in Table I, was especially noticeable in the drilling of epidosite. The "longheat" drill steels furnished by Company "A" drilled 154 pct more minutes than the "standard-heat" steel. Expressed in feet, the "long-heat" steel drilled 114.60 ft more before failure than the "standard-heat" steel. The "long-heat" steel furnished by Company "B" drilled 37 pet more minutes or 60.39 ft more before failure than the "standard-heat" drill steel. The effect of the long heat treatment was not as evident when the steels were drilling in greenstone (Table II). In greenstone, the increase in minutes drilled by the "long-heat" steel over the "standard-heat" steel was 47 pet and 1 pet, respectively, for Companies "A" and "B."

Jan 1, 1952

By C. S. Lord

"The Regal Silver mine is 5 miles north-northwest of Albert canyon; a station on the main line of the Canadian Pacific railway; 21 miles east of Revelstoke; British Columbia.Development, commenced in 1918, comprises more than 8,000 feet of workings from six adits, one of which extends into the Regal Silver property from the adjacent Snowflake ground. Production has been limited to a little tungsten concentrate recovered recently from a few r..undred tons of ore treated in a small underground mill. The property has received some attention as a possible source of tin. The deposits are large quartz veins containing irregular sulphide bodies. Ore minerals normally make up less than 1 per cent of the veins and include pyrite, galena, sphalerite, scheelite, and stannite. The veins are approximately parallel with the bedding of the enclosing graphitic, siliceous to calcareous, slates and argillites. These strata are of Precambrian age, strike about northwest, and dip northeast. No other rocks are known in the vicinity of the workings . Granitic rocks, intrusive into t'he sediments, outcrop 4 miles to the southwest and 7 miles to the northeast and may underlie the property at no great depth."

Jan 1, 1954

By W. D. Dietzman

This Bureau of Mines report presents a profitability analysis of producing crude oil by waterflooding. Included are the estimated costs of installation of water injection and producing equipment for waterfloods at 2,000 and 4,000 feet and the estimated annual operational expenses for each in west Texas. Using these cost estimates as a base for selecting a range of costs that are indicative of producing crude oil by waterflooding, a simulation technique was derived for determining the profitability under various conditions. Because of the large number of combinations of variables used in this study, a high-speed digital computer was utilized for the calculations. The variables include operational expenses, capitalized costs, price of the oil, annual production, and leasehold acquisition cost. The results obtained from the simulations are presented Fn the appendix. In addition, a nomographical approach was chosen for presentation of the profitability. Five nomographs are presented that can be used for fast estimation of the discounted cash flow (DCF) rate of return that might be expected from a prospective or active operation under various sets of assumed conditions.

Jan 1, 1974

By C. M. WEILD

ATTENTION has been turned recently to the exploration and development of certain large blanket-deposits of brown iron-ore in Cuba. The most conspicuous of these to-day, and the one upon which the most light has been shed, is the Mayari deposit, situated about 15 miles south of Nipe bay. Here the Spanish-American Co. has sole control over 18,500 acres of ore-bearing lands, reported by its engineers to contain 500,000,000 tons of ore; and the necessary plant and equipment, with docks and railways, is now under construction for the early marketing of this ore. A similar deposit, and undoubtedly the next to be exploited, is the ore-field at Moa bay, where 13,000 to 15,000 acres of ore-lands, immediately adjacent to the shores of an excellent harbor, have been generously covered by numerous mining-claims, practically all controlled by four large interests. This deposit is now estimated to contain approximately 350,000,000 tons, on the basis of dried ore ready for shipment, a figure which may be increased when the western limits of the ore-deposit have been more accurately defined. Other deposits of the same type, but smaller and less accessible, are those at Cubitas, situated from 12 to 15 miles north of Camaguey city, and at Taco bay and Navas, points lying a few miles west of Baracoa. The area of the Cubitas deposit is said to be 6,000 acres, and the yield of ore is estimated at 150,000,000 tons. The Baracoa. deposits are less well known, but preliminary estimates have placed their joint ore-reserves at 40,000,000 tons. Accepting the above tonnages as reasonably correct, we conclude that the deposits enumerated give promise of adding about 1,000,000,000 tons of iron-ore to the world's supply; they have, therefore, to be considered in any attempt to fore-

Aug 1, 1909

By E. J. Harris

Data obtained from mine ventilation pressure and quantity surveys are required to accurately diagnose ventilation problems, project future air quantity needs, and to locate conditions adversely affecting the efficiency of a mine ventilation system. A method for making mine ventilation pressure surveys with aneroid altimeters was presented in Bureau of Mines Information Circular 7809, and a description of field calculation technique is presented. This report supplements Information Circular 7809 by developing the information obtained during a mine ventilation pressure survey into a single equation suitable, with appropriate modification, for use with desk-top calculators and digital computers. The equation can be used to calculate the ventilation pres sure from the base station to any underground station, or between any two underground stations, and can be programed for semiautomatic sequential calculation using a desk-top calculator. An example of application to a programed desk-top calculator is provided in the appendix.

Jan 1, 1973

By E. H. Rose

IN these days of the spectacular in research and technological accomplishment, it is easy and natural to overlook some of the applications to everyday life of recent developments of a more pedestrian kind, or to fail to realize that sometimes two or three of the latter may be combined to serve a novel purpose in fields other than those in which they grew. The present remarks are to point out three such developments which might be combined to apply to an everyday function of the A.I.M.E. as an organization. By its Constitution, the A.I.M.E. is organized "to promote the arts and sciences connected with . . . minerals and metals, and the welfare of those employed in these industries . . .; to hold meetings for social intercourse and the reading and discussion of professional papers, and to circulate . . . among its members the information thus obtained . . .; and to . . . maintain . . . a library." By these words of Article I the profession of mining and metallurgy is recognized to involve many arts and sciences, of which the art and science of exchanging information is a leading one. As to methods of preparing or securing papers, the Constitution is silent.

Jan 1, 1944

By H. C. Voges

The concentration of cassiterite at Iscor's Uis Mine is described, and information is given on aspects of the concentration of iron ore at Thabazimbi and Sishen Mines. At Uis, a very Iow-grade tin ore is concentrated by three-stage jigging, spiral concentration, and tabling to give a high-grade concentrate with a recovery of 80 per cent of the tin. A Iow-grade tantalite-columbite concentrate is also produced. The possibility of recovering mica, the use of sluice boxes instead of spirals, and the recovery of cassiterite from minus 45 µm material are being investigated. At the two iron-ore mines, heavy-medium separation is applied to size fractions larger than 0,5 mm. The types of ferrosilicon and the circuits used for the recovery of ferrosilicon from the various dilute-medium circuits are described. The spiral-concentration plant being installed at Thabazimbi for the treatment of the minus 0,5 mm portion of the ore is described.

Jan 1, 1982