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By E. R. DeMen

In late 1965 General Mills announced the availability of a new liquid ion exchange reagent, LIX®-64, for the recovery of copper from various solutions, such as dump leach liquors. Acceptance of this material by the copper industry has been gratifying. A number of pilot plants have been operated, and at this writing there are four commercial plants either in operation or under construction. The properties and operating characteristics of this reagent have been described in previous papers.1,2 LIX-64 is quite effective and selective for copper extractions although partially limited in pH ranges, losing extraction efficiency as the acidity of the feed solution increases to below pH 1.0. Also, the LIX-64 content in the kerosine carrier was limited to about 10 volume percent (except for special cases) because of rapidly decreasing phase disengagement rates above this content. This in turn led to large plant capital costs, as the organic flow rates had to be in- creased (rather than LIX-64 content) to extract the copper from high content liquors. This was true in all circuits where the feed copper content ran above 2.0 g/l copper. A reagent was needed which would extract copper from more acidic liquors (or higher copper content liquors) and which exhibited improved phase disengagement characteristics with reagent contents up to 30 volume percent. General Mills is pleased to announce the availability in commercial quantities of a new and improved reagent, L+-64~. This reagent broadens the pH range in which copper can be extracted, and exhibits superior phase disengagement characteristics. The improvement in the reagent has been noted in laboratory circuits, as well as pilot plant runs and commercial operations.

Jan 1, 1970

By Richard F. Roethe

Surface coal mining productivity in the U.S. and Illinois has shown a general declining trend since 1969. The U.S. Department of Energy conducted an analysis in 1980 of the causes of declining productivity in different states. This paper presents a detailed analysis of changes in overall productivity and productivity in different functions such as overburden preparation, overburden stripping, reclamation, coal handling, etc. during the period 1970-1982. Statistical analysys techniques including multiple regression were utilized in the study.

Jan 1, 1983

By S.K. SHARMA, ANKUSH GALAV, G.S.P. SINGH

This paper proposes a hydromechanically coupled numerical modeling approach to quantify the influence of various parameters on the mechanical and hydraulic performance of protective water barrier pillars (PWBP). The results are validated for two case studies having pillar widths of 16 and 42 m at cover depths of 136 and 190 m and water heads of 25 and 141 m. The outcome can be significantly helpful in the rational design of these pillars in underground coal mines.

Mar 1, 2023

By Roy H. Werner

The environmental demands on the mining industry coupled with rising production costs have created a need for a low cost sludge removal system. The HYDRA* system meets these demands by offering a unique means of removing settled solids from the bottom of a clarifier or a thickener. This underflow system combines experience and proven concepts to form a low cost sludge removal system. The HYDRA system incorporates a flexible design that can be adapted to any settling area. The components are readily available and cost less than a conventional clarifier or thickener. Existing technology developed by preparation engineers provides for retrieval and recovery of mine preparation plant refuse. However, past retrieval methods have been extremely costly. The HYDRA system, because of its low cost, makes the complete process of retrieval and recovery economically feasible. This allows wasted resources to be converted to a saleable product.

Jan 1, 1975

By Terry O. Arney

Ore Reserve Models are well established evaluation and mine planning tools. BY definition, these models are made up of regularly sized blocks, arranged in a three dimensional matrix. Two dimensions correspond to north and east directions, and the third, to the depth or elevation. The dimensions of the blocks need not be equal, but generally at least two of the dimensions are equal. The blocks are located in space by coordinates which are generally translated into index values for computer applications. Each block will have quantitative attributes, such as grades, densities, rock characteristics, etc. assigned to it. The process of assigning values to each block in the three dimensional matrix is the process of ore reserve model development. One of several interpolation procedures may be employed to predict the value of a block, based on surrounding data. Block value models have several uses. The utilization of block models in ore reserve computations is quite common. Here, ore reserves may be calculated by level or by cross-section for the entire deposit. For each ore reserve calculation, multiple cut-off grades may be analyzed to determine the ore reserves under different cut-off conditions. The other major use of block value models is in mine simulation. Through simulation, profitable studies that analyze the effect of alternate ore removal sequences can be undertaken to determine economic optimality. Other studies that are undertaken in mine simulation problems include the evaluation of mine layout, pit slope effects, and the impact of varying cut-off grades.

Jan 1, 1974

By Hayward B. Oblad

The effects of eight independent variables on froth flotation product yield, ash content, and coal recovery were studied using laboratory batch flotation of 0.6 am x 0 coal. The eight flotation variables investigated were air feed rate, pre-dispersion of collector oil, impeller speed, product collection time, initial solids concentration, collector conditioning time, frother (methyl isobutyl carbinol) concentration, and collector (No. 2 fuel oil) dosage. The two-level Plackett-Burman screening design and the three-level Box-Behnken design were used. Within the ranges studied, air feed rate had no effect on product yield. Pre-dispersion of collector oil, impeller speed, product collection time, initial solids concentration, and collector conditioning time showed only minor effects on the product yield and quality. Frother concentration (mg/L) in the process water and collector oil dosage (g/kg) were shown to be the dominant independent variables in coal froth flotation. Flotation experiments that vary initial solids concentration at constant frother dosage (g/kg) confound the effects of frother concentration (mg/L) and solids concentration. The dominating effects of frother concentration and oil dosage on coal recovery and froth product ash content are illustrated with three-dimensional plots. The relationship between froth product ash and coal recovery is also clearly illustrated by the flotation data.

Jan 1, 1985

By Andrew W. Jenike

There used to be a time when bins were designed for total volume and placed in any available place of the plant. Poke holes were provided and feed was maintained by manual prodding, lancing, hammering, and by various mechanical flow-profiting devices. Little thought was given to what occurred inside the bins and why materials did not flow. Indeed, such mental effort was hard to justify while low-cost manual labor was plentiful, quality standards low, and rates of feed moderate. The past fifteen years have seen a drastic change in these conditions. We all know that labor for hard manual work is becoming unavailable at any wage, level. Standards of product uniformity are continuously rising. This uniformity is just as important in a fine ore feed to ball mills as it is in a cattle feed or in a flour mix. Rates of feed now frequently exceed 2,000 tons per hour per feeder. At that rate there is no time for, lancing or prodding. An efficient storage, plant contains a known available volume of bulk solid, and feeds it at the required time, at the prescribed rate, and without degradation of the product. A storage bin may also perform other functions such as blending of different grades, degasification of aerated, powders, isolation of different gaseous media. A contact bed of particles flowing by gravity in counter-current with a gas or liquid may be used as a continuous reactor. Gas or liquid pressures can be simply contained by, a sufficient head of flowing solid.

Jan 1, 1968

By Y. K. Yen, J. D. Miller, C. L. Lin

A PC image-based, on-line coarse particle size analysis system is being developed for the control of crushing and grinding circuits. Initial results had indicated that the system is accurate when tested with irregularly shaped particles which are stationary and do not overlap with each other. Now the system has been successfully tested in the dynamic mode with a moving belt conveyor. On-line size analysis for actual plant operations is discussed and includes: (1) the video system with respect to lighting and data acquisition requirements for a rapidly moving belt and, (2) image sampling, specifically the number of observations needed for accurate sampling and the total time required to perform the calculations for a representative data set.

Jan 1, 1993

By Lawrence E. Mannion

In southwest Wyoming lies buried the world's largest source of natural sodium carbonate, or soda ash. Perhaps a hundred billion tons of trona (sodium sesquicarbonate) are contained in ancient lake beds in the Green River basin'). There the Green River Formation encloses more than 40 extensive beds of trona. At least 25 of these exceed 3 feet (1 meter) in thickness and most of them are more than 300 square miles in extent. Five have been exposed in mines and lie between 800 and 1500 feet below the surface. Others lie at depths of from 400 to 3500 feet. Three companies have underground mines that supply trona to adjacent soda ash plants. These are the FMC Corporation, Allied Chemical Corporation, and Stauffer Chemical Company. A fourth, Texasgulf Corporation, has a mine under development. In 1974, annual soda ash capacity in the Green River area was approximately 4,300,000 tons, which requires the mining of about 7,500,000 tons of trona.

Jan 1, 1975

By Miguel Angel Ibarra

This paper describes the results of a digital computer simulation study in which the impact of the proposed truck dispatching on the overall mine productivity was investigated for an operating open pit mine. In the study, the existing operation was first simulated for a one-month period, using both the actual time study data and the computed cycle times. By adjusting certain input parameters to the simulation program, the actual one month production was first duplicated through simulation. Afterwards, the operation was again simulated in a dispatch mode. Comparison of simulation results under the dispatch mode, with the initial base case simulation results, showed a definite improvement in overall productivity with dispatching; i.e., approximately 10% gain for the operation. As expected, the results also showed that the extent of possible improvement did vary with the particular pit configuration being investigated.

Jan 1, 1980

By K. Hajmrle

The production of nickel coated mica composite powder by hydrogen reduction of a nickel ammine sulphate solution, followed by the production of molded plastic samples containing Ni/Mica is described. Sample preparation by injection or compression molding is outlined and the better results in compression molding are explained by the combination of better particle-to-particle contact, less particle breakage during processing, and more random particle distribution in the plastic. Three volume resistivity measurement techniques are described and compared. Two of them (conductive paint and silver-rubber electrodes) are found reliable and are used throughout the work. The influence of nickel content and particle size of Ni/Mica on volume resistivity is evaluated and the optimum product defined. One of the most important assets of Ni/Mica, its ease of injection molding, is demonstrated by the good electrical properties obtained with little optimization of the injection molding process. Surface roughness of molded plastics with and without Ni/Mica is briefly discussed. Shielding effectiveness of Ni/Mica in four plastics (PP, ABS, PBT and PC) is presented and correlated to volume resistivity data for the same materials. The addition of 15 to 50 weight % Ni/Mica (3 to 16 volume %) to plastics and subsequent injection or compression molding produces composite materials having low volume resistivities (0.03 to 1 ohm.cm) and high shielding effectiveness (40 to 70 dB).

Jan 1, 1988

By K. Thirumalai

The Bureau of Mines has developed and tested a new concept of combining thermal and hydraulic energy processes for hard rock cutting. The study shows that this novel combination method overcomes the fragmentation limitations of the thermal process in nonspalling rocks and the cuttability limitations of the hydraulic process in high-strength rocks. The method effectively cuts hard rocks at moderate hydraulic pressures (below 30,000 psi). Theoretical predictions of the rock damage process are made and are correlated with experimental results obtained by using both single pulse and continuous water jet hydraulic systems. Traversing point heating and line heating techniques were used for heating rocks preceding the continuous jet impingement. Heating induces structural weakness of the rock material and assists fragmentation by the water jet impingement. The thermohydraulic process is effective if the significant depth of heat penetration induced by the surface heating exceeds the cutting depth produced by the jet impingement. Hydraulic specific fragmentation energy values reduce by about an order of magnitude using the combination technique. The process efficiency and the rate of themohydraulic hard rock cutting increases significantly by increasing the intensity and duration of heating.

Jan 1, 1973

By Bernard A. Kilgore

Kaolin is a hydrated aluminum silicate mined primarily in middle Georgia along the "fall line", the location of the coast line in prehistoric times. It is used extensively as a filler for paper, insecticides, tires, plastics, a pigment for paints, as a coating for fine gloss paper, and for high grade ceramic products, such as catalytic converters. During its journey from the open pit mine to its final use, kaolin takes many forms, and must be handled in many different ways. The purpose of this presentation is to follow kaolin through its process and briefly describe some of the methods Georgia Kaolin Company, one of the world's largest kaolin producers, uses to handle and convey its product and some of the peculiarities involved.

Jan 1, 1983

By William Petruk

Lithium bearing lepidolites from three deposits in the province of Goias in Brazil were investigated to determine whether there is a correlation between the lithium content of the mineral and the colour of lepidolite and associated tourmaline. Such a correlation can be a useful guide to field geologists for outlining high grade ore zones. It was found that mauve-pink lepidolite associated with pink tourmaline, and brownish lepidolite associated with black tourmaline have high lithium contents, but the colour of lepidolite is not due to lithium. The pink colour of lepidolite and tourmaline is likely to Mn3+, and the brownish tint of lepidolite and black colour of tourmaline to Fe3+. Lepido lites appear to be lithium-rich when the lepidolite and associated tourmaline contain relatively high amounts of Mn3+ and/or-Fe3+.

Jan 1, 1985

By Lee S. Richardson

Silicon is usually considered to be a useful metallic alloying element. To be more truthful, it is not a metal at all, but a semiconductor, whose electrical resistance (when pure) is high and decreases with temperature. We will join the metallurgists, at least for this paper, and refer to it as a metal. In its commercially available form, silicon is metallic in appearance, brittle, with a density of 2.33, less than that of aluminum. Silicon dioxide or quartz has a high heat of formation, which not only makes the metal a useful reductant for other materials, but also makes it difficult to reduce from its ore. The melting point is 1412°C, slightly less than steel, but substantially higher than aluminum or cast iron. The alloys of silicon with iron, usually called ferrosilicons, have some unique advantages. The melting points of most alloys are substantially below those of iron or silicon (Fig. 1). The two major compounds formed (FeSi and FeSi2) help somewhat in the reduction of silicon by their energies of formation, but the influence of these phases on the mechanical properties is more important. Four major groups of alloys are made -- silicon metal (>95% silicon), 75-85% ferrosilicon, 50% ferrosilicon, and silvery pig iron (12-22% silicon). The alloys between 50 and 65% silicon and between 25 and 40% silicon are normally avoided because of structural instabilities, presumably of the two compounds, leading to disintegration of the alloys on cooling.

Jan 1, 1974

By Joseph F. Shirley

A froth flotation plant to recover by-product molybdenite must be designed specifically for the selected separation process and the type of ore being treated. However, some general rules concerning by-product molybdenite plant design can be suggested that would be valid for most processes. The term by-product molybdenite in this paper is limited to the recovery of molybdenite from copper porphyry ores, which essentially amounts to selectively separating molybdenite from copper and iron sulfide concentrates. In addition, most of the discussions would apply only to the almost universally used approach of floating the molybdenite and depressing the copper and iron sulfide minerals.

Jan 1, 1979

By Shosei Serata

In the past, salt cavities for storage of liquid and gaseous fuels have been developed and operated using practical experience as a guide rather than rock mechanics principles and practices. Although many salt cavities are still operating satisfactorily. some of them are beginning to show various problems associated with long-term deterioration of the cavities. This paper describes a major breakthrough in the rock mechanics design of solution cavities which is the development and application of the REM computer simulation system. From the computer simulation analysis, the long-term deterioration process of cavities can be related to the basic parameters of rock mechanics design and the storage operations. The computer simulation system is also used for optimizing cavity design and operational specifications. This optimization technique is explained by its application to the three basic storage systems: 1) open dry storage system for liquids and solids 2) open wet storage system for liquids 3) pressurized storage system for gases, liquids and solids The effectiveness of the optimization technique is illustrated with some field examples by showing the direct interaction between the computer simulation system and field data of a test well including tectonic stress conditions, material property coefficients and geological anomalies.

Jan 1, 1974

By Bruce Kennedy, Dan Nilsson

Mining means drilling and blasting in order to break down the rock, loading and transport, and often also crushing the ore down to a suitable size. These operations can be done in open pits or in underground mines, and also, to a lesser extent, in marine mining. The same operations are also used in various types of construction, i.e., for roads, water power stations, etc. Before beginning a detailed economic analysis of the factors which enter into deciding whether to mine by open-pit or underground mining, and at what point a change should be made from open-pit to underground mining, or vice versa, it is of interest to consider some general factors.

Jan 1, 1982

By W. F. Riggs

INTRODUCTION Flotation equipment is becoming more definitive in design as well as greater in dimension. The last ten years have witnessed the implementation of large flotation cells ranging in size from 28 to 85 cubic meters. However, small plants still operate with cells as small as 3 cubic meters. These changes have increased the operational sensitivity of the flotation system to the chemical reagents used. No scientific study has been undertaken to develop the relationship between the size of equipment and the response of reagents in the flotation system. Hence, this article is an attempt to present several observations from past experience for the purpose of stimulating future research in an area previously ignored and perhaps subsequently not used to advantage. CONVENTIONAL FLOTATION Recent advances in conventional flotation cell design have been made in two areas: a. Flotation cells are becoming larger, and b. Basic design of flotation cells has changed. They can be classified into two types: deep cell and shallow draft cell. Size and design changes of flotation cells have a greater effect on frother performance than on the performance of other chemical reagents. Hence, the discussion in the following sections is restricted to the impact of frothers in the flotation system. Flotation Cell Size The advent of increasing flotation cell size has resulted in the increase of frother consumption. There appears to be a correlation between reduced horsepower (kilowatt) consumption and increased frother consumption per ton of ore processed in the circuit. This is more prevalent when the frother chemistry remains unchanged. Another reason for increased frother consumption is the increased distance between the rotating central shaft and the lip of the cell for larger flotation machines. Increasing this distance results in increased surface area corresponding to the larger cell size. Reduced power input per ton combined with the need for longer, stronger load support of the froth bubble as a result of increasing cell size has resulted in the development of a new series of stronger and more persistent frothers. By the same token, these newer, stronger frothers are difficult to control when applied to the smaller cells. This is true even at lower dosages because the break point between too much frother and not enough frother for optimum metallurgy is normally very narrow. This problem is often exaggerated when operators have established an optimum setting for pulp level and air for the particular frother in use. Generally, the tendency is to operate the flotation cells simply by adjusting frother dosage. The increase in frother strength to accommodate the large cells often results in the realization, after a retrofit, that the existing pump box or sump which is still handling the same volume of concentrate is no longer adequate in size. Flotation Cell Design The two most common flotation cell designs installed during the past ten years are the deep cell and the shallow draft cell. The deep cell provides for complete mixing of air and pulp at the bottom of the cell. The shallow draft cell does all the mixing/pumping in the bottom haft of the cell whereas the mixing of the air is performed further up the shaft and is brought into contact with the pulp midway up the vortex. There are many preferences for one or the other. It is the author's contention that both designs have very valid concepts and must simply be suited to the particular situation as required by the operator. The following comments are subjective observations which should be explored in greater detail. The deep cell mixes both air and pulp together at the bottom of the cell requiring a full depth ascending of the homogenized air to the surface to form the froth layer. This design, in combination with charged air, provides for good concentrate grade control under adverse conditions of selectivity, especially when faced with a fine grind and a slime-laden gangue. A selective frother can be applied without a competitive loss in recovery. One of the conditions for good selectivity in this environment is operating at medium pulp solids concentration in the range of twenty-six to thirty-four per cent (26-34%). When a higher solids concentration is used in combination with a coarse grind, it becomes difficult to maintain the same recovery with a selective frother due to higher pulp viscosity. This condition sometimes results in an unacceptable coalescence of the air bubbles as they ascend the full height of the deep cell. The increased pulp viscosity at higher solids concentration can also retard the flotation kinetics. The combination of decreased surface area of dispersed air and slower kinetics can result in reduced recovery causing coarse particles to continue to drop

Jan 1, 1989

Though the mining industry is beset with problems-a broad slump in metal prices, a rash of acquisitions and takeover attempts, rising capital costs, and an aggressive Canadian energy program-there was an under-current of optimism at the 1981 AMC conference that's been missing at industry meetings in recent years. The industry anticipates a turnaround in the 1980s, buoyed perhaps by the new spirit of cooperation from the Reagan administration. For the first time in years, it appears that Washington and the mining industry share mutual goals for developing the nation's resources. A number of prominent Reagan officials were on hand during the three-day conference in Denver, September 28-30, to reassure conferees that restrictions plaguing energy and minerals development would be eased. Interior Secretary James Watt and other government speakers promised cooperation in bringing balance to federal public lands policies, a review of regulations that have hampered the industry, and prompt action on domestic minerals policy. Daniel N. Miller, Jr., assistant interior secretary for energy and minerals, said, "It is our intent to dismantle the overhearing bureaucracy that has stifled mineral and energy exploration. We know that Interior's rules have shackled the mining industry in recent years, and we know that those rules must be eased." Miller noted that the administration will not permit mining on national park lands or wildlife refuges, but added that "we must assess a variety of uses of public lands ... we will restore lands to multiple use where practical." EPA administrator Anne Gorsuch assured industry representatives that the administration intends to work within environmental laws and with Congress to review and revise water, soil, and air pollution policies. "We have a strong commitment to see that there are major mid-course corrections" of air regulations, Gorsuch said. Support from these "new friends in Washington" will be crucial in light of the serious problems pressuring the industry. Copper prices have plunged to almost three-year lows and prices for molybdenum, gold, and silver have slumped. Earnings are down and today's high interest rates prevent a quick turnaround. Companies are on edge after the recent takeovers of Kennecott, St. Joe Minerals, and Texasgulf Though the companies may benefit from the major injection of capital that large energy firms can provide, many observers fear the new parent companies won't be willing or able to survive the cyclical metal markets. Arco and Gulf Resources, for example, have been criticized for closing Anaconda's Montana copper facility and the Bunker Hill unit in Idaho, respectively. Canada's national energy program has brought additional pressure on the industry. This policy, which emphasizes Canadian majority ownership of the country's energy sources, resulted in acquisition of Texasgulf's Kidd Creek lead-zinc-silver complex by Canadian and French interests. In response, the American Mining Congress adopted two resolutions on takeovers. One calls for the US government to review laws regulating tender offers and takeovers "to better ensure that principles of fairness and sound investment policy govern such transactions.'' The other asks the government to demand "fairness and reciprocity" as a basis for US policy governing international trade in minerals and investment relations with other countries. AMC's shopping list included four other priority goals, aimed primarily at the Interior Department: • Prompt implementation of Interior's efforts to bring order and balance to rules governing access to public lands for exploration and development. • Statement by the President of a comprehensive and coherent domestic minerals policy. • Amendment of the Clean Air Act to remove impediments to productivity and barriers to economic development that are not necessary to essential goals of the act. • Development of new approaches to better achieve worker health and safety in the most cost-effective manner without penalizing productivity. Almost 6000 mining industry executives attended the 1981 convention-the largest in AMC's 84-year history. As in years past, the conference offered a wide spectrum of presentations-nearly 100 papers in 26 sessions-ranging from commodity forecasts to the latest technical achievements. New Administration Stockpile Goals The minerals availability session included a presentation on management of the minerals stockpile by Paul K. Kruege r of the Federal Emergency Management Agency. Krueger notes that rather than providing incentives for development of a domestic raw materials industry, the government has "a history of providing disincentives to industry." In mining industries, he adds, the rate of productivity growth has been -6% over the last six or seven years. Krueger feels there will be a major change under the Reagan administration. In March 1981, FEMA began the first purchase program for the national defense stockpile in over 20 years. The stockpile is sadly out of balance, Krueger adds. Stockpile materials are

Jan 12, 1981