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By J. S. Wakeman

INTRODUCTION The primary purpose of comminution circuits in the mineral industry is to reduce an ore to a particle size that will permit separation of the valuable minerals from its gangue constituents. Wide variations in the mineral content and physical characteristics can and do occur throughout a given mineral deposit From the standpoint of their effects on the comminution characteristics of an orebody, these variations may not be identified by the normal sampling and analysis procedures utilized to delimit an orebody and to characterize its grade distribution. The proper design of a comminution circuit for a mineral deposit is very important to the success of that enterprise. It is also an expensive unit process both from the standpoint of capital and operating costs. It is, therefore, essential that any sampling program be designed to identify the variations that may occur that will affect this circuit. Because of the variety of comminution systems that are available, it is also essential that the sampling and subsequent evaluation program be sufficiently comprehensive to identify potentially inappropriate systems or flowsheets. It would be impossible to describe in a single chapter the techniques and approaches that should be utilized for sampling every type of orebody. Each orebody is unique and requires a sampling and testing program designed to its specific requirements for exploration, characterization and circuit design. The following is a general discussion of the guidelines to be used and considerations to be made in establishing such a program. SAMPLE SELECTION When sampling an ore deposit for the purposes of equipment and flowsheet selection for comminution, it is important that the sample composites for grind testing be chosen on the basis of how they will affect the comminution circuit rather than just how they might affect the subsequent metallurgical operations. For example, grindability, classification and liberation size characteristics are more important to the comminution circuit than ore grade. Mineral deposits may contain a multiplicity of ore types that can vary extensively in the dissemination of minerals and optimum liberation size requirements; and may also vary as much as 100% in ore hardness. The accumulation of samples for grind characterization should be done in such a way as to allow the identification of this variation. A proper mineralogical evaluation of the samples obtained to characterize an ore deposit can be a great aid in identifying the individual ore types within the deposit

Jan 1, 1982

By Charles J. Johnson

The United States is totally dependent on imports for all primary chromite and most ferrochrome supplies. Although the United States imports chromite and ferrochrome from a number of countries, the long-term future of chromite supplies appears to lie in southern Africa (Republic of South Africa and Zimbabwe) where 88 percent of known world reserves exist. Floreover, low mining costs and the availability of low-cost electricity for ferrochrome production gives South Africa a comparative advantage over most other chromite and ferrochrome-producing nations. A well-known problem faced by the United States is that when viewed from a longer-term perspective, the major sources of supply of metallurgical grade chromite and ferrochrome may be subject to disruption. The three countries that have caused the greatest concern have been the Republic of South Africa, the Soviet Union, and Zimbabwe. South Africa presents a particularly difficult problem because it may be subject to internal political unrest and/or U. N, economic sanctions. South Africa has increased its share of world chromium production from about 30 percent in 1968 to 62 percent in 1978.1

Jan 1, 1982

Council and Standing Committees - 1981/82 President: G. Y. Nisbet. Senior Vice-President: Prof. A. N. Brown. Junior Vice-President: Prof. R. P. King. Honorary Treasurer: Prof. D. G. Krige. Immediate Past President: Dr P. R. Joehens. Members of Council: B. C. Alberts, J. D. Austin, P. T. Fewell, C. E. Fivaz, J. J. Geldenhuys, Dr A. K. Haines, P. N. Harris, H. E. James, C. G. Knobbs, Dr B. K. Love¬day, Dr J. Lurie, C. S. MacPhail, D. G. Malan, J. C. Mostert, G. C. Thompson, Dr H. Wagner. Chairman, Witbank/Middelburg Branch: B. Rohrmann. Chairman, Orange Free State/Klerksdorp Branch: K. F. W. Eick. Chairman, Materials Engineering Specialist Division: G. Pienaar. Past Presidents serving on Council: Dr M. G. Atmore, H. Britten, Prof. D. D. Howat, Dr J. P. Hugo, D. G. Maxwell, Prof. R. P. Plewman, Dr R. E. Robinson, Prof. M. D. G. Salamon, P. W. J. van Rensburg, D. A. Viljoen, P. A. von Wielligh. Standing Committee Chairmen: Constitution, Rules and Policy, Dr P. R. Jochens; Membership, Prof. R. P. King; Training, Career Guidance and Education, P. A. von Wielligh; Journal, Prof. A. N. Brown; Monograph Series, D. G. Malan; Technical Programme - Metallurgy, C. E. Fivaz; Technical Programme - Mining, P. N. Harris; SAIMM Schools - Metallurgy, Dr B. K. Loveday; SAIMM Schools - Mining, J. D. Austin; 1982 CMMI Congress, Dr M. G. Atmore; Awards, Dr P. R. Jochens; Adjudication, Dr P. R. Joehens; Phoenix National Committee, Dr M. G. Atmore; Excursions, J. C. Mostert; Mines and Works, Prof. A. N. Brown; World Mining Congress - National Committee, Prof. R. P. Plewman.

Jan 1, 1982

By A. P. L. Kotzé

This paper gives a brief description of the control measures used in the establishment of the Grootegeluk Coal Mine, near Ellisras in the Transvaal. Specific reference is made to the planning offunds, cost and financial control, and economic evaluation.

Jan 1, 1982

By Clintford R. Jones, Om P. Pande

This chapter presents a survey of instrumentation and control systems used on ball mill circuits from the past to the present. It is based on the concept of optimization of plant practice, and addresses the influence of the circuit design on the control strategy and on the instrumentation philosophy. Methods of optimization of the grinding circuit, within the constraints of the mill design requirements, are reviewed. The modern use of automation and circuit optimization is critically reviewed for known and possible conceptual control loops. A comparative study of circuit variations due to instrument hardware, location and installation is provided. Future trends i.e., computer control (DDC) and the effects on both the control stratagems and the optimization stratagems are described.

Jan 1, 1982

SACPE has asked the Journal to bring the following points to the notice of members who are about register with SACPE. When to Apply There is no set time to apply for registration. Engineers should apply when they believe that their training has met all the requirements of Policy Statement No. 1/3. Pitfalls Remember that it is the applicants' training that must be evaluated, and this requires the avoidance in the application of vague generalities such as 'My duties were design plant including its economic evaluation' or 'I was engaged in . . Requirements An example of what is required can perhaps best illustrate the point.

Jan 1, 1982

By J. D. Anthony

The Australian continent possesses significant reserves of a wide range of minerals, including bauxite, coal, copper, diamonds, gold, iron ore, lead, manganese, mineral sands, nickel, phosphate, silver, tin, uranium, and zinc. Australia's identified economic resources of many minerals are very large as indicated in Table 1. A sophisticated and highly experienced mineral industry is now an established feature of the Australian economy and Australia is the world's largest exporter of iron ore, alumina, mineral sands and refined lead and amongst the leading suppliers of many other commodities such as coal, lead and zinc ores/concentrates, nickel, refined zinc, tungsten concentrates and bauxite. The industry exports 70% of its production. This is reflected in the value of Australian mineral exports which have grown from about $200m in 1960/61, comprising 10% of total export receipts, to about $1265m or 29% of export income in 1970/71 to around $7061 representing 37% of Australia's total export income in 1980/81. Details of the more significant minerals are as follows: Japan (42.1%) USA (11.3%) ASEAN (6.3%) UK (5.9%) F.R. Germany (3.8%) Republic of Korea (3.4%) New Zealand (2.6%) Also see Table 2. AUSTRALIA'S MINERAL RESOURCES POLICIES Federal and State Governments' Responsibilities Australia has a federal system of government comprising six States, a self-governing Territory and a Federal Government. Under the Australian federal system the Constitution sets down the powers of the Federal Government. All powers not assigned to the Federal Government in the Australian Constitution reside automatically with the States. Certain of these broad powers result in the Federal Government having a significant influence on resources development. For example, in being responsible for economic management, the Federal Government's fiscal and monetary policies have an important effect on industry as well as on State finances. In particular, the taxation regime employed by the Federal Government is of direct importance to decision-makers in the resources industry. The Federal Government is responsible also under the Constitution for external trade matters; and international trade and commodity matters are increasingly important in Australia's international relationships. Foreign investment is another area where the Federal Government has a role to ensure that national interests are protected. This foreign investment power flows from the Federal Government's control of foreign exchange movements into and out of Australia. However, before enlarging on these and others of the Federal Government's powers and policies, it should be emphasized that the State governments, by virtue of their wide powers to regulate matters within their own boundaries, are more directly involved in the day-to-day administration and regulation of mining operations. For instance, the powers of the State governments include the responsibility-for the granting of exploration rights and mining leases, the approval of mining operations and the levying of royalties and other like charges. Administrative arrangements covering the granting of minerals and petroleum exploration and development titles vary from State to State. Before development rights are granted, State governments consider environment protection and rehabilitation aspects of development proposals. The provision of infrastructure within State borders is a matter primarily of State government responsibility. It is usual practice in Australia for State governments to construct and operate infrastructure services such. as railways, ports and electricity generation and transmission. The States may also provide certain public services such as electricity. and water, port and loading facilities, communications, health and education services which form part of the infrastructure of mining operations. In remote areas the mining companies themselves usually are expected to provide much of this infrastructure. However, the Federal Government is primarily responsible in some fields, such as telecommunications and parts of the railways network. State governments carry out preliminary exploration and geological mapping and some are directly involved in the mining of coal for power generation. The Federal Government's responsibilities in addition to economic management, taxation, international relations, foreign capital and investment, include regulation of exports, environmental matters and matters affecting the Aboriginals of the Northern Territory. FEDERAL GOVERNMENT POLICIES The continued sound development of the minerals and energy resources sector is regarded by the Federal Government as being of very great importance. However, the Government does not seek to participate directly in resource developments. It sees its role rather as that of establishing a sound economic and policy climate in which private companies can identify opportunities, seek out customers and marshall the necessary capital for the development of resource projects.

Jan 1, 1982

By Theodore R. Butkovich, Jesse L. Yow

Geological storage of spent-fuel assemblies from an operating nuclear reactor has been underway since the Spring of 1980 at the U.S. Department of Energy's Nevada Test Site. The primary objective of this generic test is to evaluate granite as a medium for deep geological storage of high level reactor waste and to provide data on thermal and thermomechanical behavior of granite from imposed heat loads.(l) The underground installation in the Climax stock granite was sited at about 420 m below the surface and 145 m above the existing water table. As shown in Figure 1, three parallel drifts were excavated spaced on approximately 10 m centers. Seventeen storage holes were drilled at the central drift on 3 m centers in which eleven spent fuel canisters and six thermally identical electrical simulators were emplaced. Electrical resistance heaters were emplaced in vertical holes in the floor of the side drifts on 6 m centers. The thermal output of these heaters is being periodically adjusted to simulate the thermal response of a large storage array. Rock and ventilation air temperatures are being measured continuously in the drifts and throughout the rock surrounding the excavations. Measurements of drift deformation have been made routinely since the emplacement of the spent fuel. Both vertical and horizontal measurements are being taken at five locations along the heater drifts and at six locations along the central canister drift (Fig. 1). Two types of instrumentaton are being used: convergence wire extensometers which are monitored automatically, and a manually operated tape extensometer with which measurements are taken periodically. The tape extensometer measurements were initiated about 6 weeks following fuel emplacement. The lack of a temperature correcting capability for the convergence wire extensometers make that data unavailable for analysis at this time.

Jan 1, 1982

Engineering availability of the 120/200 tonne Wabco haulpak fleet at Mt. Whaleback was in the mid fifties and unstable. The project to achieve a reliable 66% during 1980 highlighted "plannable" maintenance, short cycle scheduling, condition monitoring, backlog control, and, above all, the importance of involving all affected people. It is not sufficient for consultants to design systems and make them work. The people who use the system must understand it, support it and "own" it. In this way, they will develop it and improve results after the outside help has been withdrawn INTRODUCTION In early 1979, PA proposed a programme to improve engineering availability of the Mt. Newman Mining fleet of 70 Wabco haulpak trucks of which 53 were 120 tonne and 17 were 200 tonne units. (Subsequently five 200 tonne trucks from Hamersley Iron were added to the fleet). The ore truck workshop was also responsible for 75 tonne trucks used as water trucks and general purpose vehicles. The need for action was clear. The fleet was achieving availability in the "mid fifties" with wide variations indicating that the fleet was becoming unreliable. Projected tonnages required a reliable 66% availability to be

Jan 1, 1982

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982

By Robert W. Freedman

This report describes sampling and analytical procedures used for measurement of sulfates in diesel tailpipes and in the diluted exhaust within dilution tunnels. A variety of methods exist for sulfate analysis for such systems, including ion exchange. Two chemical methods used by the Bureau of Mines are described in detail. These are based upon spectrophotometric measurement of chloranilic acid using barium chloranilate. The procedures are rapid and relatively inexpensive. In general, ion exchange is preferred by many analysts for sulfate analysis. However, it is more complex and expensive than chloranilic acid procedures, which are adequate for exhaust analysis.

Jan 1, 1982

[Page Vernal Mortensen, RMCMI President 1982-1983 2 RMCMI Officers 1982-1983 4 Treasurer's Report 198 1-82 5 Remembrance of Deceased Members 6 Roster of Advertisers 7 President Ira E. McKeever's Address 9 1982 New Member Listing 10 "Which Shall it be - Pity or Pride?" Keynote Address, Dr. William S. Banowsky 17 "Don't Desert the American Dream - Fulfill it!" Carl Terzian 22 "The Image of the Coal Industry" Symposium, Charles W. Margolf, Chairman 33 The Honorable Michael Enzi 34 Harris D. Sherman 38 Robert Golten 40 Ralph Looney 43 "Sure You Have an Image - But What Kind?", Carl Terzian 46 Resolutions 77 Advertisements 79 Acknowledgment, Appointment 111 Invitation to 1983 RMCMI Meeting 112]

Jan 1, 1982

By Jorgen Elbrond

In a stream of ore in an underground mine or in a beneficiation plant bins are installed between machines or machine system. When the upstream machine is stopped the downstream machine can continue operation for a while and vice versa. The paper describes a procedure for calculating the total capacity of a system consisting of two machines with an intermediary bin as a function of the bin's live volume and of the installed machine capacities and their production variations, which are defined. Extensions to several machines in parallel and in series are shown as well as practical examples.

Jan 1, 1982

US 4,195,426-Manganese nodules are recovered from relatively great depths on the ocean floor using a self- propelled remote-controlled vehicle having a V-shaped tubular structure with a system of crawlers at its apexes. Underneath each side of the V-shaped structure is a scraping system for gathering nodules and directing them into a tubular conveying system for elevation to the surface ship. A given area of sea bed is fully mined in a single pass of the vehicle. V. Banzoli, V. Di Tella, and P Vielmo, assigned to Tecnomare, SPA. Apr. 1, 1980. 5 pp. 137-60) Filed. 3-31-78 (892,197). Priority: Italy, 4-1-77 (84119A/77).

Jan 1, 1982

By James W. Mahar

The following paper summarizes our observations on building response to mine subsidence and techniques for mitigation of building damage. The subsidence cases are located in Illinois. The general description of the geologic and mine conditions are primarily for those sites. Data on building response and mitigation measures were collected under grants supported by the Abandoned Mined Lands Reclamation Council (AMLRC) of Illinois and the U. S. Bureau of Mines, in Twin Cities, Minnesota. Case histories include pit and sag subsidence primarily beneath abandoned room and pillar mines. The majority of the paper deals with structures affected by sag subsidence. Most of the structures are one and two story homes. The first section of the paper summarizes the typical geologic and mining conditions at the sites. Building response to pit and sag subsidence follows the first section. Emphasis is placed on the behavior of concrete and masonry foundations, and wood frame and masonry superstructures. The third section describes mitigation techniques used to prevent or minimize building damage. A summary of the observations and critical parameters is given at the end of the paper.

Jan 1, 1982

By E. F. W. Buermann

This paper, which is meant to be read in conjunction with the other papers on the Grootegeluk Coal Project in this Issue (J. S. Afr. Inst. Mm. Metal/., vol. 82, no. 12. Dec. 1982) deals with the extent to which civil-engineering infrastructure had to be provided for that project, near Ellisras in the Transvaal.

Jan 1, 1982

Adsorption of acrylamide based homo and copolymers on hematite was investigated as a function of phe nature of the polymer charge and functionality of the polymer. Effect of addition of sodium dodecylsulfonate and dodecylamine hydrochloride was also studied and was determined to result in an increase or decrease in the amount of polymer adsorbed depending on, the charge characteristics of the surfactant and the polymer, pH of the suspension, concentration of the various species and the order in which these species were added to the system. The surfactant adsorption under given conditions on the other hand, was found not to be affected by the presence of the polymer molecules. The data is analyzed to elucidate the mechanism of adsorption of polyacrylanide type polymers on hematite both with and without the surfactant species king present in the system.

Jan 1, 1982

By Kerry Burns

Contrary to active subsidence, which occurs concurrently with mining operations, or is completed within a few days following coal extraction, delayed subsidence may take many years to appear at the surface after coal mines are abandoned. There are two principal morphological types of delayed subsidence: troughs, which are shallow depressions, and sinks, which are steep-sided crown pits. Both types are damaging to surface structures, and a variety of methods have been introduced to deal with the problem, ranging from subsidence insurance to site restitution. In planning insurance or restitution measures, a predictive model is of value in estimating the magnitude of the problem and the size of long-term budgetary commitments. Only one model is known, which was developed for the Bureau of Mines by GAI Consultants of Monroeville (l,2,3). The GAI model is presented in qualitative terms. This report develops a formal basis for the model and tests a numerical implementation on one of the best-described study areas, Allleqheny County in Pennsylvania.

Jan 1, 1982

By L. W. Brandt

As part of its objective to expand the body of mineral information as a basis for new technology, the Bureau of Mines conducted research on the fundamental behavior exhibited by phosphate clay waste in settling ponds. A semiempirical equation used to describe the compaction of ceramic powders in a single-acting die was applied to aqueous phosphatic clay waste and attapulgite slurries. This equation, [*V = a1 e ?k1/P + a2e ? k2/P] was found to describe the compaction of an attapulgite gel and a phosphate slime gel by a moving screen. [*V] is the ratio of the compaction achieved at a given pressure, P, to the compaction achieved at a pres-sure sufficient to remove all space between particles. The constant al represents the fraction of compaction achieved at low pressure by rearrangement of floes to higher packing density, and a2 represents the fraction of compaction achieved at higher pressure resulting from removal of voids within floes. K1 and K2 are constants determined from the experimental data. Both the low-pressure and high-pressure compaction mechanisms were observed in the compaction of the clays. These two compaction mechanisms offer an explanation for the observation that impounded slimes initially dewater rapidly and then dewater at a much slower rate.

Jan 1, 1982

By K. H. Singh, J. N. Szuck, J. A. Riddell

"Hydraulic rock drilling equipment has been in use at Falconbridge over the past two years in both production and development situations. This paper deals with the experience gained in the application of hydraulic drilling in the company's mines and discusses the benefits and problems encountered during their use. The paper primarily focuses on technical, operating, maintenance and economic aspects of the machines, and does not attempt to compare the performances of different machines from the various manufacturers.IntroductionThe Sudbury Operations of Falconbridge Nickel Mines Limited are comprised of five operating mines and two mines under development. All the production comes from underground mines, mostly at depths below 1000 metres. The company, faced with increases in operating costs and difficult mining conditions, has continued to seek solutions with the help of new mining technology.The development of electric-hydraulic drilling machines in Europe had been pursued with great interest and, in 1979, a decision was made to test these machines to prove their technical and economic viability under operating conditions. Since then, a number of electric-hydraulic machines have been evaluated in different situations and currently nine hydraulic machines are being used in the company's various mines. These machines are comprised of two-boom drilling jumbos for development, one-boom machines for longhole drilling and a large-hole-diameter drilling rig for blasthole drilling. One hydraulic jumbo has also been used in a cut-and-fill stope."

Jan 1, 1982