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By D. M. S. Bhatia

Five sulfide minerals from the Magiwnt mine, southeast Missouri were analyzed for 31 trace elements in over 300 samples by laser microprobe spectrographic analysis of polished sections. The concentration of several trace elements shows a pattern of progressive variation with depth (space) and variation with different paragenetic stages (time) of each mineral. Factor analysis of the geochemical data shows sympathetic correlation both in space and in time of Bi, Cd, Ge, and Sn in galena and sphalerite, and Ni and Co in sphalerite and marcasite.

Jan 1, 1979

By T. D. Wheelock

The effect of various flotation depressants and surface treatments on the floatability of coal derived pyrites in the presence of XIBC was investigated with a modified Hallimond tube microflotation cell. The floatability of pyrite particles which had been cleaned with hot dilute (5%) hydrochloric acid was relatively large. However, the floatability of such particles was reduced greatly by the addition of specific depressants such as calcium hydroxide and also by treating the pyrite with an aerated warm alkaline solution. Although this treatment and these depressants also had some effect on the floatability of coal particles, the effect was much less than on the pyrite particles.

Jan 1, 1979

By T. G. Carnahan

The Bureau of Mines investigated a flotation-nitric acid leach procedure as part of the goal to maximize minerals and metals recovered from primary and secondary domestic resources. Studies were conducted on an ore that contained carbon-bearing and sulfide mineralization that rendered a portion of the ore refractory (resistant) to conventional leaching technology. The procedure investigated for treating the ore consisted of the following: (1) separation by flotation of the carbonaceous and sulfidic components from the ore, (2) leaching the flotation concentrate with nitric acid at 100° to 110° C, (3) leaching the flotation tailings with sulfuric acid, and (4) processing the combined leached slurries in a conventional manner to recover yellow cake. In step 2, HN03 is converted to gaseous products from which it is regenerated by reacting these products with air and water for further leaching. An overall uranium extraction of 96 pct was achieved by this procedure.

Jan 1, 1979

By Michael A. Toole, O&apos

INTRODUCTION The tremendous capital investment required to produce a low grade ore deposit demands a reliable answer to the question: "How much does it cost to drill a well to produce the uranium that geologists have indicated is there in the ground?" However, you will find the answers given will be many and varied, depending on whether they come from the operating company, the drilling contractor, a geologist, a reservoir engineer, purchasing agent, or whoever. Each generally considers only a limited area of the total operation. The operating company usually depends upon the drilling contractors, service companies, and consultants to supply expertise. Because it is often difficult to see the "whole picture" or even to agree upon what the "whole picture" is, planning a well program and its costs is often done piecemeal. Frequently, costs "saved" in one area of the program are needlessly spent in another, because the effect of one area upon the other was overlooked. Since the drilling fluid is such an influential part of the drilling program, it should be given utmost consideration when planning the overall program. As W. D. Lacabanne wrote in 1954: "The drilling fluid system is understandably called the heart of the rotary oil drilling rig. Any other type of rotary rig.... should benefit by the incorporation of mud fluids in the drilling scheme." And G. R. Gray mentions that "The driller recognizes the drilling fluid as one of the useful tools available to solve drilling problems." However, in minerals drilling, only in recent years has the drilling fluid been considered as more than a tool to get through special problem areas. Although there are many similarities between drilling for oil and gas and drilling for minerals, the differences in the drilling equipment used justifies designing specific fluids for the minerals drilling industry. NL Baroid/NL Industries, Inc. has been a leader in introducing such fluids and in providing technical know-how to the minerals drilling industry. The purpose of this paper is: (1) to discuss the selection of drilling fluids to meet specific drilling conditions during both exploration and production and (2) to show the interrelationship among factors present in the exploration and production phases that influence total well costs. DRILLING FLUIDS FOR DRILLING PROBLEMS The drilling fluid is a tool that can be used to improve drilling performance by improving hole cutting, cleaning, stability, and formation productivity. Properly formulated and maintained drilling fluids enable the drilling operation to be carried out with increased efficiency and lower total (overall) costs. However, it should be noted that not all drilling problems can be solved by even the most carefully prepared and maintained drilling fluids. Of the many possible drilling problems encountered in a well before reaching target depth, this paper will discuss only those most likely to be present in the shallow [61 to 610 m (200 to 2000 ft)] drilling operations in South Texas. LOST CIRCULATION Loss of circulation is the most common problem encountered in drilling. Because the losses occur under varied conditions, it is often difficult to determine the exact causes. "Lost circulation" or "lost returns" means the partial or complete loss of drilling fluid to voids in the formation. "Loss of water" while drilling with water may take place into any permeable section and should be distinguished from "water loss" or filtration of fluid through the filter cake of mud solids laid down on a permeable formation. "Loss of water" can frequently be stopped by the addition of colloidal sized clay particles such as high yield bentonites, whereas "water loss" may be controlled with organic polymers. Subsurface conditions that lead to loss of circulation can be classified as: (1) natural fractures, (2) induced fractures, (3) unconsolidated or highly permeable formations (loose gravel), and (4) cavernous formations (crevices and channels). Loss of circulation may occur whenever the borehole pressure exceeds the formation pressure. The greater the differential pressure, the more likely it is that circulation may be lost. To stop loss of whole mud, voids must be bridged so that a filter cake can be laid down on the permeable section. The plugging material must be of the proper size and shape to offer greater resistance to the fluid flow around it than the flow up the annulus. A plugging composition that satisfies these requirements may not be able to be handled by the small rig pump available.

Jan 1, 1979

By Robert R. Dorfler

We ought not look back unless it is to de- rive from past errors, and for the purpose of profiting by dear bought experience. - George Washington During the mid 1960's, the application of automation was introduced to Climax by two process control companies. In 1969 Climax decided to seriously consider improved control of selected areas of their milling process after preliminary research had been completed on two rougher ball mill grinding circuits. In 1971 the Climax Mill Department developed a direct digital control scheme for rougher milling, designed a remote control center for handling process water, planned to automate the central steam heating facility for energy conservation, and convert other plant areas to automation. All twenty rougher grinding mills and the industrial water system were automated by 1977. The idea of automating central heating and other areas was abandoned although some fuel conservation items were installed at the heating plant. During this period from 1971 to 1978, the mill capacity was expanded from 39,000 metric tons per day to 43,000 metric tons per day and cyclone classification was introduced to rougher milling. Ore quality changes degraded the milling recovery from over 90% to less than 85%. This report describes the procedure the mill used in developing the automatic process and the occurances that affected the timing and fina1 control logic. The report deals primarily with the automation of the ball mill grinding, classification and flotation process as this was the bulk of the seven-year project.

Jan 1, 1979

By Isobel Clark

The problem of the estimation of ore reserves is essentially a simple one to describe. Given a set of sample data, at specified locations within a deposit, how can we estimate the value (or quantity) of ore in unsampled areas. The question may be posed of a whole deposit (global) or it may be more desirable to estimate smaller volumes within the planned mine area, e.g. stopes or blocks (local). Many methods have been evolved to tackle this problem, from hand-contouring of values by the mine geologist to extremely sophisticated geomathematical analysis. The main difficulty with any estimation method in this context is that it is almost impossible to check whether the "predicted" value bears a close relationship with the "actual" value. The only reliable way to decide if an estimation method has "worked" is to test the eventual value of ore against the predicted value. This is, more often than not, impossible - even allowing for the time factor involved. To know the "actual" value of a mined block it has to be sampled intensely, and these values with their positions recorded accurately. Alternatively, blocks may be passed through the concentration process individually and these results recorded. In most producing mines neither of these alternatives are practicable or seen to be-important. Another problem with comparing in-situ (so-called) mineable reserves with production figures is the introduction of many variables into the concentration process -- dilution, wastage, possible stockpiling, mill recoveries and so on.

Jan 1, 1979

By S. Venter, W. E. Stumpf

Some of the factors that govern the choice of a nuclear fuel are briefly discussed, special reference being made to the introduction of advanced carbide fuels into fast-breeder programmes. One of these factors, i.e. the compatibility of carbide fuels with stainless-steel cladding, is discussed in depth. A very sensitive technique for the study of compatibility interactions between fuel and cladding is described in respect to the effects of particle size, specific surface area and surface oxidation of the fuel,and microstructure of the cladding on the compatibility behaviour of the cladding with the fuels. Finally, the need for the development of modified or stabilized uranium carbide fuels is discussed, and some results are presented to show the effects of small amounts of sulphur in these fuels on their compatibility with stainless-steel cladding materials.

Jan 1, 1979

By T. E. Bernard

The CO2-absorbent canisters used in four approved rescue breathing apparatus were investigated. A breathing machine was used to simulate human expiration with gas flow rates of 26, 37, and 48 1/min of 3.5% CO2 in air. The exit gas CO2 concentration, the pressure drop across the canister, and the exit-gas temperature were monitored. The absorbent capacities of the packed-bed canister designs were found to be dependent on flow rate within the range studied, while the capacities of the other designs were less affected. The radial canister had the least resistance to breathing while the complex bed design proved to be the most effective in utilization of the chemical. The overall results indicated that LiOH (lithium hydroxide) has the highest capacity for CO2 absorption among the absorbents tested. It can be used in a simple packed-bed design while maintaining acceptable levels of resistance and exit-gas temperature. Examination of oxygen supply with respect to CO2-absorption capacity suggested that it is desirable to closely match CO2-absorption capacity with the avail-able O2 supply to minimize the size and weight of rescue breathing apparatus.

Jan 1, 1979

By H. Wesley Peirce

Although not generally recognized, Arizona has rock salt deposits unique in the United States. This uniqueness stems from a combination of two factors: (1) relatively youthful geologic age and (2) nonmarine origin. Although Arizona shares one deposit with Nevada (Figure 1, No. I) there are three others within the State (Nos. 2, 4, 5) that are believed to be both late Cenozoic in age (less than 15 million years) and nonmarine in origin. The only other recognized nonmarine salt deposits in the U.S. are much older, being in the early Cenozoic (Eocene) Green River Formation of Colorado and Wyoming. According to Johnson and Gonzales (1), the remaining rock salt deposits in the United States are marine and either Paleozoic or Mesozoic in age. Of the seven localities shown in Figure 1, six in the Basin and Range geologic province are believed to represent nomarine late Cenozoic phenomena and one (No. 7) in the Colorado Plateau geologic province is Paleozoic (Permian) in age and marine in origin. The following comments are intended to update the general geologic highlights of these deposits and to summarize the nature of their present utilization.

Jan 1, 1979

By Edward R. Rose

This paper summarizes and emphasizes the potential importance of Canadian rare-earth occurrences, and recommends that efforts to locate and evaluate rare-earth deposits should be increased. Increasing world markets, depending on intensive applied research into the numerous unique and remarkable chemical and physical properties of the rare-earth elements (REE), are developing; their properties and uses are becoming better known; methods of separation are much improved. The REE group comprises a Cerium (Light) subgroup of 7 metals and an Yttrium (Heavy) subgroup of 9 metals. REE are trace elements in many rocks and minerals, and major constituents of more than 50 rare-earth minerals, many of which are difficult to detect and identify. They occur preferentially in acidic and alkaline igneous and metamorphic rocks, including carbonatites, as well as in placer deposits, certain uranium deposits, phosphate rocks and others. The main ores now are bastnaesite (in Precambrian carbonatite), monazite and xenotime (in Recent beach sands) as well as uraninite and brannerite (in Huronian quartz-pebble conglomerate) and loperite (perovskite) and apatite (in alkaline complexes). World resources are summarized. Twenty mines in 1973 produced an estimated world total of about 31,000 tons of contained rare-earth oxides (REO), 19,341 tons of which came from one mine at Mountain Pass, California. A selected fifteen, of 315 or more Canadian occurrences, are briefly described and compared, and their relative merits indicated. Their abundance and variety suggest the possibility of finding high-grade deposits in many geological terranes in Canada.

Jan 1, 1979

By Larry B. Bramlett

Regional radiometric, magnetic and geologic data point to Copper Mountain as an area of general uranium favorability. Sub-regional radiometric and magnetic data direct interest to a specific section of an overthrust Precambrian granite. Detailed magnetic and resistivity surveys in this area show local targets of interest, one of which corresponds to Rocky Mountain Energy's North Canning deposit. On the basis of these data a second and previously untested target was drilled resulting in the intersection of uranium horizons similar to those at North Canning. This integrated geophysical approach can be used for uranium exploration in geologically similar areas.

Jan 1, 1979

By J. A. Ryder

Compressed air is a relatively inefficient yet very convenient vehicle for transmitting mechanical energy. It is inefficient when compared to, say, hydraulic or electric energy systems since compressor and pneumatic machine efficiencies are quite low (in the range 20-65%) and reticulation losses can be quite high unless adequate pipe diameters are used to minimize friction drops. It is convenient in that capital and maintenance costs of pipes and machines are exceptionally low, the equipment is flexible and lightweight, the technological level is simple, the form of the energy supply is intrinsic- ally safe, and as an additional minor but psychologically important benefit, it provides a ready source of cooling and air supply for emergency use in deep hot mines. It is for these reasons that compressed air is a premier source of energy for many forms of underground equipment, in particular hand or rig-mounted rockdrills, some forms of rock- handling equipment, and a host of minor applications including agitators, small-lift pumps and temporary f am installations. In a typical S. African deep-level gold or platinum mine, compressed air generation accounts for 15% of the total mine electrical energy bill - more than is used for hoisting. In these mines it is not uncommon for over 100 km of underground compressed air piping to be installed, primarily to supply handheld rockdrills.

Jan 1, 1979

By E. Steel

The asbestifom habit is most commonly developed in certain amphiboles and chrysotile, but other minerals may also crystallize with this unususual habit, The habit may be characterized by 1) a fibril structure, single or twinned crystals of very small widths (generally less than 0.5 inn) which have gram with a common fiber axis direction but which are disoriented in the other crystallographic directions, 2) anomalous optical properties, primarily parallel extinction, 3) unusual tensile strength, 4) high aspect ratio, and 5) flexibility. In addition, there is evidence to indicate that some amphibole asbestos may have unusual surface properties.

Jan 1, 1979

By Stephen R. Hunt

This paper summarizes some preliminary results of the Illinois State Geological Surveys current investigation into surface subsidence resulting from coal mining in Illinois. The purpose of the study is to characterize-the vertical movements that may result from various types of underground coal mining. In general there is relatively little published information about subsidence from room-and-pillar mining as compared with longwall mining. The findings of this study, based on mining operations in a variety of geologic settings, delineate the magnitude, shape, and position of the subsidence profile. Comparisons of case histories of subsidence are based primarily on the extraction ratio and the general geometry of the mine (depth, panel width, and mining height).

Jan 1, 1979

By R. C. Troxell

Alternative methods of analyzing data acquired by the Morenci copper concentrator process control instrument-computer system are presented. Experimental measures of ore characteristics, for proposed feed forward control, are introduced. These include on-line indexes of ore hardness, ore density, ore dusting, and ore color. Comparison of metallurgical results before and after computerized process control implementation, allowing for differing ore grades, oxidation, hardness, and fineness of grind, also is described.

Jan 1, 1979

By Paul H. Earl

This paper discusses the evolution of a modeling methodology for explaining price behavior in the aluminum industry. Three generations are described, each utilizing as a foundation a microeconomic stages-of-processing approach. The second generation represents an improvement over the initial version, by incorporating more rigorous specifications of energy cost, and market strength (demand-supply balance) as well as endogenous treatment of market strength. International linkages across prices, costs, and markets, are the major extensions in the third generation. The discussion covers theoretical considerations, data problems and limitations, and model specifications. Simulation and forecasting properties of the models are also addressed.

Jan 1, 1979

By Paul M. Bommer

Abstract. This cater presents the development of and results from a computer model of in-situ uranium leaching. This model uses a streamline-concentration balance approach and is useful with a vide range of reservoirs. It can be used with any type of veil system, in a reservoir with or without boundaries, and with any form of descriptive kinetics. The model also includes the effects of dispersion and consumption of oxidant by minerals other than uranium. The effects of areal sweep, variable uranium concentrations, variable permeability, and the presence of oxidant consumers on uranium production are shown and discussed.

Jan 1, 1979

By R. B. Dunn

Whilst coalmining in the United Kingdom has been synonymous with longwall mining practice there have been changes in recent times which have enabled not only an extension in the length of the face to be worked but also in the ability to extract both thick and thinner seams. Additionally the industry has taken a positive view in the extension of retreat methods of extraction applied for different reasons both to particularly thick and specially thin seams. To permit development of a flexible programme to meet these diverse needs, it has been necessary to design machinery along with mining systems specially suited to these requirements. In reviewing current UK thinking special emphasis is made on the extraction of thinner seams generally of higher quality coal at moderate depths with a commentary on some recent results.

Jan 1, 1979

By D. C. McLean

One of the few innovations in hydrometallurgy in recent years has been the utilization of the chemistry of basic iron sulfates called jarosites. These have been used to make iron-zinc separations in the processing of zinc concentrates and are a very important factor in both the Duval and Cymet copper chloride processes as a means of preventing iron build-up in the closed leaching circuits. Copper oxychlorides are kindred compounds in that they are insoluble basic salts that form at low pH (1.5 to 3) and precipitate selectively from many base metal solutions. They have been reported in the chemical literature as far back as 1860, and a few of them are known in their mineralogical forms (particularly atacamite) usually as nuisance minerals because of their chloride content. Several patents describe their synthesis and use as fungicides and insecticides, and papers have discussed their formation as corrosion pro¬ducts on copper and brass piping (14).

Jan 1, 1979

By Rudolf Fahn

Bentonites are best suited for the preparation of acid activated clays with efficient adsorption properties. They are weathering products of acid volcanic ashes and their natural deposits are world-wide spread. The main constituent of bentonite is the aluminium hydrosilicate nontmorillonite with a high ability to swell. Süd-Chemie owns bentonite deposits in Germany and subsidiaries in Italy, Mexico and Arizona.

Jan 1, 1979