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By William A. Kennedy, Jonathan R. Stahl

This paper deals with the phenomenon of water held in a leach dump due to capillarity. Water is shown to be retained in the fine pores of the ore as well as in the interstices between the rock and soil particles. Upon drainage, Chino leach dump material shows two distinct capillary systems and a double capillary curve is often obtained. Both the igneous and the sedimentary rocks composing the leach material are shown to have appreciable porosity but little permeability. Fluid flow is, therefore, restricted to the interstices between the rock and soil particles. The irreducible water saturation for the aggregate is found to be 884 for the -48 mesh material and 235 for the448 mesh to one inch material. The composite sample of minus one inch dump material had an irreducible water saturation of 52 percent. The irreducible water saturation in the fine pores of the ore was found to be between 73 and 76 percent. Very coarse pores or channels between large rocks exhibit essentially zero capillary retained water. The presence of fine material in a dump can cause high water saturations to be retained and these saturations may be mistaken for perched water tables. Perched water tables can be drained but capillary water will be retained. Capillary pressure data can aid in distinguishing between perched water tables and capillary retained water.

Jan 1, 1974

By P. I. Lipman

Largely forgotten by today's environmentalists and mineralogists is a pioneer scientist of the nineteenth century named Ellen Swallow. Fortunately, the memory of her accomplishments has been resurrected by Robert Clarke in his biography, Ellen Swallow: The Woman Who Founded Ecology. Her direct contributions to the field of mining included authoring First Lessons in Minerals and an analysis of the rare mineral samarskite which indicated the presence of an insoluble residue; her findings led to the eventual discovery of samarium and gadolinium. While enjoying the distinction of being the first woman student at the Massachusetts Institute of Technology, she successfully isolated vanadium in an ore which other experts had examined without detecting the metal.

Jan 1, 1974

By J. Leja, N. Sheikh

The stability of lead ethyl xanthate precipitate in aqueous environment of different pH (4.5 to 10.5) and at temperatures 25°C-60°C was investigated. Dissolution leads to a wide variation of pH, xanthate, and lead ions concentration in solution and to a deposition of solid products of reactions. X-ray diffraction patterns of these solids enabled identification of Pb(OH)3, PbCO3, and PbS as constituents of the remaining undecomposed Pb(EtX)1, together with some unidentified compounds (which give rise to intensive peaks with d values of 2.82A and 1.71A, and numerous peaks of lesser intensity).

Jan 1, 1974

By R. W. Smith

An amine used as a collector in a commercial flotation process is usually a rather impure substance. The differences in ionization constants and solubilities of various amines undoubtedly affect their collecting power or strength. This investigation explores some of the differences among several amines of similar (although not precisely the same) chain lengths. An attempt is made to relate the differences to both observed contact angle and Hallimond tube flotation behavior in quartz systems.

Jan 1, 1974

By E. T. Turkdogan, B. B. Rice

Desulfurization of limestone during and subsequent to calcination has been investigated using U.S. Steel's Rogers City quarry-Michigan limestone cut to 25-30-mm diam spheroidal shapes. The experimental observations indicated that the sulfur present as iron pyrite in commercial limestone is oxidized partly to SO, during calcination and partly converted to sulfides (FeS, CaS) and CaSO4. If calcination is carried out under oxidizing conditions, most of the sulfur is converted to CaSO4, which can be removed from burnt lime readily in CO,-CO mixtures, the higher the CO content the faster is the rate of reaction. In the 30-mm-diam spheroids gas diffusion in the pores of limestone and burnt lime is fast relative to rates of the desulfurizing reactions. Over the temperature range investigated, e.g., 850° to 1200°C, there is internal desulfurization.

Jan 1, 1974

By D. R. Piteau, A. MacG. Robertson

Strength, permeability, and deformational properties of a rock mass are influenced and often controlled by the geological discontinuities within the mass. These properties are often determined by physical tests conducted within and on portions of the rock mass under consideration. Any extrapolation of these test results to other portions of the rock mass assumes that a similar pattern of discontinuities, having similar properties, exists throughout the region of extrapolaion. A survey in which various joint properties of interest are measured may be conducted to sample the joint population of the mass. Suitable data manipulation and handling techniques are developed to permit the definition of the joint population of the rock mass. The validity of the extrapolation of test results may then be assessed.

Jan 1, 1974

By Fathi Habashi

Chalcopyrite can be readily leached with HNO3, but the recovery of elemental sulfur does not exceed 50% under the most favorable conditions. Preheating at 500°C in a slightly reducing atmosphere increases the recovery of elemental sulfur to about 65%. Chalcopyrite can also be treated with HNO3 in a pressure reactor at 110°C to solubilize selectively the copper while iron remains in the residue as an oxide. The recovery of elemental sulfur also improved when preheated chalcopyrite is treated in this way. Stainless steel should be an adequate material of construction.

Jan 1, 1974

By F. A. Olson, S. L. Pohlman

A unique method of measuring weight loss as a function 3 of time, with a sensitivity of 10-5 grams, while leaching copper minerals with a flowing acid leach solution has been developed. Kinetic results obtained coupled with visual and microprobe analyses show topochemical reaction for the leaching of chrysocolla with sulfuric acid. The kinetics follow a shrinking core model and show ion diffusion through a product layer, chemical reaction at the unreacted core interface and mass transfer through the boundary layer as being important.

Jan 1, 1974

By Tuncel M. Yegulalp, Peter G. Zambas

In planning an underground room-and-pillar mine, the selection of the shaft or portal location and the orientation of the main haulage arteries is of paramount importance, particularly in view of the high dependence of the cost of truck haulage on the proper definition of these parameters. In an effort to facilitate this selection a computer program was written which, by relating the truck characteristics to the areal configuration of the property or ore body, derives the volume-weighted total fuel and time requirements for hauling ore from every panel within the property to a specified portal or shaft location through a predetermined gridwork of haulage drifts. By varying the size and orientation of the gridwork and the location of the portal or shaft access, an infinite number of configurations can be investigated. The results of this analysis can be plotted to indicate the optimum conditions.

Jan 1, 1974

By M. E. Wadsworth, A. E. Lewis, R. L. Braun

Experimental results obtained in laboratory leaching studies of primary copper sulfide ore in sulfuric acid systems pressurized with oxygen are interpreted by a computerized geometric model involving the movement of a reaction zone through the ore fragments. Physical properties of the ore, including size, shape, and mineral content, are considered. The leaching mechanism involves mixed kinetics and includes a surface reaction within a moving reaction zone plus pore diffusion of dissolved oxygen through the reacted portion of the ore fragment to the reaction zone. The results are applicable to conditions that would exist in nuclear solution mining or similar processes in which the ore is converted into rubble and then inundated by a leach solution adequately supplied with oxidants. Experimental results at 90°C are correlated with the model, which includes temperature-dependent parameters.

Jan 1, 1974

By W. J. C. Venter

The use of activated carbon to improve the selectivity in the separation of base metal minerals from bulk concentrates played an important role in the development of separation techniques employed at Tsumeb Corp.'s Tsumeb and Kombat mines. The Kombat mill fiowsheet and metallurgical data are given with particular reference made to the separation techniques using activated carbon. The mine's historical background, geology, and mining methods are described briefly.

Jan 1, 1974

By Paul M. Musgrove, Larry S. Diaz

Recent tests conducted at Inspiration Consolidated Copper Co. examined some aspects of the value of a continuous measurement of particle size to the operation and control of a mill grinding circuit. Inspiration's control objectives and kinds of control systems developed in recent years to attain these objectives are outlined. A description is given of the arrangement of the test circuit at Inspiration and also of the systems used to measure particle size of the cyclone overflow product in these tests. Use of on-line size measurement for the analysis and improvement of grinding circuit performance is illustrated by relating how two important relationships were detected. Finally, the performance of a particle-size-based control system is described, including preliminary conclusions as to increased productivity.

Jan 1, 1974

By Duane H. Haley

The century we live in has been an eventful time for the Third World, particularly the country of Peru. Although it will take one or two generations more to see its end and fully evaluate its scope, it is already clear that during the twentieth century, Peru has entered a dynamic industrial, economic, social, and political revolution. This century has seen the end of old governments, and the introduction of reforms which radically change complex traditional patterns. It also has marked the beginning of an era in which the government has elected to undertake, as a national effort, most of the future economic growth of Peru. For the most part, large multinational mining companies, which have helped to discover and put into operation large mineral and ore deposits in Peru, have been sympathetic toward this philosophy. Most big foreign companies, in addition to capital, brought with them to Peru an efficient technology, modern management, and an effective organization for the further processing, sales, and distribution of refined commodities. Nationalization of all basic resources, including mining, is the, trend-not, it is hoped, to the detriment of established technology and production.

Jan 1, 1974

By Charles H. Jacoby

The solution mining of evaporites has a history of approximately 5,000 years. The insitu leaching of metalliferous ore will have many of the same characteristic problems which have confronted industry for years in the production of evaporite minerals. Basically we will be converting the less soluble forms of valuable metals into their more soluble salts and producing these in much the same manner as, for example, sodium chloride. There are a number of problems which we are faced with that are more complex and complicated and, therefore, will require a higher degree of sophistication than previously employed. One of our most important undertakings will be the clearcut definition of the problems involved. While a great deal of expertise can be drawn from the solution mining of evaporites and the oil industry, problems peculiar to the hydrometallurgical field will need to be solved. One of these is the introduction of permeability into an impermeable rock so as to expose the sought after values of metals which by volume are infinitesimal when compared with sodium chloride, potash or other type water soluble mineralization. After establishing this permeability which will be miniscule when compared to a solution cavity, there will be the maintenance of this permeability. In general, salt deposits are of a somewhat uniform chemical composition and thus their chemistry was relatively simple. Each metalliferous ore body is somewhat unique in its chemistry and will need to be treated accordingly.

Jan 1, 1974

By N. S. Parate

Detailed analysis is given of the influence of water on the strength of limestone. The mechanism involved in strength reduction is described. Such analysis is of importance in geological, civil, constructional, mining, and metallurgical engineering and is closely associated with the rock mechanics involved in these areas. Mine dumping, slope stability, excavations, sedimentation, etc., are very much affected by the presence of water. Tensile stresses, which have an important role in the development and propagation of fissures, are produced by water in cracks. The development of fissures can be responsible over a long period of time for an ultimate, catastrophic failure.

Jan 1, 1974

By R. E. Ford, P. Tarassoff, P. H. Jennings

Copper oxide ore may be leached at all sizes from run-of-mine down to pulp, and consideration must be given to all available methods in determining the most economical one. Heap leaching was evaluated in a pilot plant at Gaspe Copper Mines, Ltd. which was designed to simultaneously leach two 1200-ton dumps of ore. The plant was operated for two years, in part under severe winter conditions. Two modes of leaching were investigated: acid leaching in which sulfuric acid was added externally to the leach solution, and pyritic leaching in which pyrite concentrate was added to the dump and acid was generated in situ by bacterial action. The pilot plant operation is described, and the results are compared with laboratory data obtained in 6-in.-diam columns. It is concluded that pyritic leaching offers certain operating advantages over acid leaching when copper is recovered by cementation in that iron buildup in the solution is prevented.

Jan 1, 1974

By Robert L. Braun, Arthur E. Lewis

A contained nuclear explosion is proposed to produce a chimney of broken ore well below the water table. After the chimney is filled with water and reaches hydrostatic equilibrium, oxygen, under pressure, is introduced near the bottom of the mass of broken rock. The increase in solubility of oxygen at high hydrostatic pressure is sufficient to initiate the oxidation of the primary sulfides, chalcopyrite and pyrite. The oxidation and dissolution of these sulfides produces enough heat to increase the temperature of the ore and water in the chimney as much as 100° to 150°C. The rate of dissolution of chalcopyrite exposed to oxygen-saturated solutions becomes so rapid under these conditions that the rate of copper extraction becomes limited by the accessibility of chalcopyrite to the solutions. Means of solution control and distribution of oxygen in the chimney have been examined in some detail. A calculational model utilizing experimentally determined solubility rates is utilized to estimate the temperature rise in the chimney and the rate of copper recovery as a function of initial temperature, sulfide content of ore, and size of ore particles. It is concluded that the high pressure and high temperature obtainable in a large ore mass broken by nuclear explosives promise the rapid and economic recovery of minerals not considered soluble by conventional in-situ leaching methods. The method should be broadly applicable to the kinds of deep deposits that must be depended on for future production and with minimum disruption of the environment.

Jan 1, 1974

By D. F. Lascelles

D. F. Lascelles (School of Earth Sciences, MacQuarie University, North Ryde, N. S. W., Australia)- The paper contains many misconceptions commonly held by both geologists and soil scientists with regard to soil processes. The analogy between supergene copper enrichment and "nickel laterite" deposits is quite apt and the use of nomenclature from the former in describing supergene nickel deposits is justified. However, care must be exercised with regard to the notable differences in

Jan 1, 1974

By John F. McElhiney, Hosseim Kazemi

This chapter is a review of fluid flow and mass trans- port in fractured rocks. The topics include: single-phase and multiple-phase flow theory, formation productivity or injectivity improvement by artificial fracturing, and mass transport associated with fracture acidizing. Possible extension and application of such ideas to in situ mining in fractured rocks are presented.

Jan 1, 1974

By Johannes Moeljono, Werner Wenzel, Heinrich Wilhelm Gudenhau

As an important mechanism for increasing production of the suction-draft-sinter process, it has been shown that gas permeability through the sinter layer plays an important role. Methods to increase production rates have been indicated and suggestions for carrying out the process have been made to improve the rate of production, reduce the fuel consumption, and at the same time obtain a uniform sinter. Laboratory experiments were conducted at the Institute for Ferrous Metallurgy of the Technical University at Aachen to illustrate these methods. Methods of Increasing Gas Penetration Through Sinter Layers The following are of fundamental importance in determining the process cycle during the sintering of iron ores: 1) Generation of maximum temperature, since its form and range determine sinter quality. 2) Propagation velocity of the temperature maximum which controls the attainable output. 3) The convective heat transfer which influences the velocity of travel of the temperature maximum.

Jan 1, 1974