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By V. A. Mironenko

The combined study of ground water regime and rock deformations has resulted in the theoretical substantiation of the common principles for analysis of the hydrodynamic and geomechanical processes Within the scope of unique scientific direction -hydrogeomechanics (Mironenko and Shestakov, 1974). The hydrogeomechanical models are widely used now for the analysis and forecasting the extremely important processes connected with the safe and efficient mining operations, as well as with the protection of geological medium. Among these processes are: -deformations of the open-pit slopes and spoil dumps; -consolidation of rocks due to the ground-water pressure drop; -water-end-rock material inrush into mine workings caused by deformations of the undermined rock mass; -geodynamical processes due to the changes in ground water regime; -artificial hydrofracturing in rocks; -transformations of clay linings under the tailing ponds and other technical water basins.

Jan 1, 1990

By M. William Lallman

Potash production from natural brines of the Bonneville Salt Flats has a comparatively long history dating back to the start of World War I. However, it vas sot until the late 1930's that a successful commercial potash operation was achieved by a firm known as Bonneville Ltd. While improvements in operating techniques, pond design and equipment have been incorporated as they became available it should he understood that the basic technology developed in the late 30's and early 1940's by Bonneville Ltd, for potash production has not been changed significantly. The purpose of this paper is to present a brief review of the history, geology and hydrology of the Bonneville Potash operations and discuss the cur¬rent methods employed for brine collection, solar evaporation and the recovery of potash and other brine chemicals. A detailed study of the hydrogeology of the Bonneville Salt Flats wan made by L. J. Turk,1 Ph.D. thesis for Stanford University in 1969, under the auspices, of Kaiser Chemicals the Industrial Chemicals Division of Kaiser Aluminum & Chemical Corporation. Turk's thesis furnished much of the information presented in this paper.

Jan 1, 1976

By John D. Price

In the constant search for ways and means of improving the quality of coke and thus making its use at the blast-fornace more satisfactory and economical, it has become increasingly evident that the present laboratory tests do not show the full picture of a coke's value as a blast-furnace fuel. This fact was recognized by Dr. A. C. Pieldner thirty-five years ago: (Ref. 1) here is perhaps no phase of fuel technicology which has aroused more discussion or regarding which there is more difference of opinion than the properties of coke which make it most suitable for blast-furnaces and other uses." Dr. Fieldner followed this assertion with a statement to the effect that men who write on this subject today (1923) have, because of conflicting experimental evidence brought forth in recent years, far less positive opinions on the matter than did writers of some years past. One is led to wonder if these statements are not just as true now as they were when first made.

Jan 1, 1959

By L. John Minnick

A revised and expanded edition of a previous paper** dealing with reactions of calcium and magnesium oxides and hydroxides with pulverized coal fly ash is presented. Lime-fly ash specimens were cured at constant temperature and subjected to X-ray diffractometry, differential thermal analysis, pozzolanic reactivity tests, and microscopical investigations. Bars of limefly ash were subjected to cycles of wetting and drying, and measurements of length change were recorded. A discussion of variations within and among types of lime and types of fly ash is presented. The nature of the pozzolanic reaction is reviewed, particularly as related to compounds which are used up and formed during the aging process. The relationship between the pozzolanic reaction and the resultant physical properties of the mixtures is examined.

Jan 1, 1968

By M. S. Fraley

As we compete for close margins in wholesale sales, the effects of both quality and price have a major impact on the cost of producing electricity.SO2 emission allowances have traded as low as$60/ton to as high as $215/ton over the last three years. This price spread in emission allowances clearly demonstrates the correlation between the quality of fuels versus the price utilities will be willing to pay for them. This paper provides an overview of the effects of the qualities of fuel, coupled with transportation as well as environmental concerns on the price of fuel and the ability to compete in a deregulated electric market.

Jan 1, 2000

By L. Barry Phelps

The application of an open-pit Materials Handling Simulator (OPMHS) to analyze mine planning and scheduling problems in large surface mines is discussed. The mine chosen for this application employed a large stripping dragline working in tandem with a shovel-truck haulback system for removing overburden. Large bottom-dump trucks were employed behind a coal loading shovel to transport the exposed coal out of the pit. Specifically, the current operations and the recommendations for short term and long term improvements were simulated on OPMHS. The effects of changing the operating parameters of the equipment on the total system were evaluated. Several alternatives were also studied for the best use of the existing equipment if the current operating parameters could not be improved upon. The results of the application are discussed.

Jan 1, 1978

By Fred Delabbio, Sverker Hartwig

As openpit copper operations transition from surface mines to underground, the speed of underground infrastructure construction prior to production is critical for maximizing the value of the project. Typically, the preferred underground bulk mining method is block caving. In preparation for future underground projects, Rio Tinto made the strategic decision to invest in a step-change program that would develop system solutions to reduce the construction time of block caves. The program focused on improving safety and doubling or more the construction speed of both vertical shafts and horizontal infrastructure compared to existing drill-and-blast rates. After an extensive selection process, Rio Tinto selected the Atlas Copco mobile miner machine as one of the concepts to proceed with for construction of horizontal infrastructure for access and footprint. In addition to un-derground drilling and hauling equipment, Atlas Copco?s Robbins mobile miner concept (a previous attempt at horizontal mechanical excavation) completed trials at Mount Isa, Pasminco and Taisei. Rio Tinto selected the new Atlas Copco mobile miner machine concept for a number of reasons including the use of proven technology from the three previous mobile miner machines and other commercial products, as well as the ability to install complete ground support typical with high rock stress conditions at approximately 1,500 to 2,000 m (4,900 to 6,500 ft) depth. Atlas Copco, with support from Rowa, the Swiss company that specializes in back up systems for tunnel boring machines (TBM), is advancing the detail design of the access version of a tunneling system on behalf of Rio Tinto. Because of the different requirements between an excavation system for access tunnels and that for tunnels on the footprint, two different versions of the mobile miner machine technology were envisioned. The access and the footprint versions of the Atlas Copco mobile miner machine share a majority of key technologies and systems. Therefore, it was possible to conduct a performance conformation test using a full-scale version of the access machine that would also mitigate the technical risks for the footprint version. To alleviate confusion, this article focuses on the access version of the Atlas

Jul 1, 2010

By Harlan L. Kebel

Gypsum, the dihydrate form of calcium sulfate, has a history of usefulness to man dating back several thousand years, and a worldwide industry has been built on the mining and processing of this versatile industrial mineral. However, anhydrite, the other prin¬cipal calcium sulfate mineral, has very limited use, so much so that separate statistics for it are not always kept, but are usually included with those for gypsum. Although often found in close association, the two minerals have important chemical differences in that anhydrite is the anhy¬drous form of calcium sulfate (CaSO4) whereas gypsum is the dihydrate (CaSo4.2H20). These two molecules of combined water result in significant differences in hardness, density, and solubility of the two minerals. Of most importance, however, is the difference in thermal properties wherein gypsum, upon the application of a modest amount of heat, can be converted to the hemihydrate of calcium sulfate (CaSO4 '21H20) or plaster of paris, an intermediate product upon which is based over 90% of the value of all calcium sulfate end products. Anhydrite, on the other hand, is inert at these temperatures and its uses have been limited to only those few cases where calcium sulfate in the anhydrous form may have an advan¬tage. The earliest known use of gypsum plaster dates back some 5000 years to the time of the Pharaohs of Egypt who had discovered that gypsum rock, when exposed to fire, broke down into a powder which, when mixed with water, would form a putty that could be plastered on a rough mud brick or stone wall to make a smooth finish. It was used down through the centuries in a limited way for ornamental purposes, but did not achieve wide acceptance because of the quick (25 to 30 min) setting or hardening time which made it difficult to use. The first real understanding of gypsum chemistry was developed in France about 1755, and the gradual growth of its present utilization dates from that time. In the United States, the first utilization of gypsum was to grind it to a fine material for use as a soil conditioner at about the time of the Revolutionary War, and the term land plaster for ground gypsum was coined and has remained in use. Another cementitious material-lime or calcium oxide-had become the usual plastering material, but by about 1870 a method for retarding the set of gypsum plaster was discovered; today it has almost completely replaced lime as a plastering material. In recent years, gypsum products sold in the United States have reached a total valuation of approximately $2 Gpy as illustrated in [Table 1].

Jan 1, 1994

By Yunxing Cao, Xinsheng Zhang, Bingbing Meng, Shuaifang Guo, Li Wang, Junsheng Zhang

During the initial process of mining a longwall working face, it is often found that the roof will not collapse readily, which increases the risk of later roof collapse disasters. Explosive and hydraulic fracturing are common roof weakening techniques; however, they have certain limitations. In the present study, CO2 fracturing was used for roof weakening during the initial mining phase in the Changcun coal mine, China, which is a novel strategy. First, by analyzing the lithological characteristics of the working face and applying combined beam theory, the breaking spans of the top coal, immediate roof, and main roof were determined before weakening. An F-35 CO2 fracturing device with a rated pressure of 270 MPa was used, which provides fracturing energy equivalent to 0.968 kg of TNT. The fracture radius of the main roof was studied by ANSYS/ LS-DYNA combined with the hanging roof-breaking theory to determine the optimal layout of CO2 fracturing drills. The results show that the breaking spans of the top coal, immediate roof, and main roof were reduced by 3.99 m, 7.66 m, and 22.03 m, respectively. The main roof collapsed as the working face advanced, eliminating the chance of later roof collapse disasters. Compared with hydraulic fracturing and explosives, CO2 fracturing is safer and more practical, giving it significant application potential.

Nov 23, 2023

By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025

By A. L. Hinde

The recovery of heavy minerals by gravity concentration during grinding is practised widely in the minerals industry. Studies have shown that the grade and recovery of the concentrate depends not only on the performance of the concentrator but also on the degree of liberation achieved in the mills and the scavenging action of the hydrocyclones closing the grinding circuit. In the current study, consideration is given to the development of mathematical models to quantify and unify the operations of comminution, liberation, classification and concentration. The models are based on test work done at production scale with gold ore.

Jan 1, 1985

By Dongjie Zhang, Fengyu Ren, Xudong Li, Yanjun Zhou, Yang Liu, Rongxing He, Jianli Cao

Based on the limiting-equilibrium analysis of roof processive caving in hanging wall caving method and the critical medium column theory, a new model of subsidence prediction caused by sublevel caving mining method was proposed in this study, considering the drawing influence and the dynamic process of filling granular media. Meanwhile, the distribution rules for lateral pressure with different orebody dip were studied under drawing ore, and subsequently complemented the model. This model indicated that the surface subsidence scope decreased as the unit weight of crack rock and the orebody dip increased. In addition, the height of critical medium column showed a decreasing trend as cohesion of rock mass, the internal friction angle and the unit weight of rock mass. Also, the method of predicting the scope of surface subsidence in the Dabeishan Iron Mine was applied. The results showed that the relative errors are less than 9% and the prediction method could be used in practical application.

Feb 24, 2022

By Michael F. Roach, Joseph K. Cavey, Gary E. Taylor

A rigorous horizontal drilling and chemical grouting program was specified beneath the Hollywood Freeway (U.S. Route 101) section of Los Angeles Metrorail Contract C-311.Twin 6.67-m (22-ft.) diameter starter tunnels were to be conventionally mined through amixed alluvial and bedrock face consisting of silty sand, gravel, and weathered sandstone and siltstone of the Topanga Group. The contact between the alluvium and bedrock dipped toward the Crossover Excavation where the horizontal drilling and grouting operations were performed. The intent of this grouting program was to stabilize the mixed face to minimize ground loss and surface settlement, and to reduce groundwater inflow into the tunnel headings. Given the highly variable mixed face conditions, horizontal drilling up to 86 m (284 ft.) resulted in upward trending trajectories which likely followed the bedrock contact. Chemical grouting was performed in a primary, secondary and tertiary, three dimensional sequence. Evaluation of the primary and secondary grouting parameters indicated where tertiary grouting was required. Grouting pressures induced a small rock failure at the tunnel heading as well as increased stresses on the tiebacks of the excavation.

Jan 1, 1997

By F. Turatti

Rio Tinto is one of the world's largest mining companies, involved in every stage of metal and mineral production, producing aluminium, copper, diamonds, coal, iron ore, uranium, gold and industrial minerals. Operations are in more than 50 countries in multiple continents and vary in location between large urban centres, regional industrial complexes and remote regions. A risk-based strategy was developed by Rio Tinto to manage its air quality impacts on a global scale. The strategy consists of three objectives ? improving air quality performance, developing industry leading practices and engaging and influencing in air issues. This paper discusses three major successes achieved this approach. Firstly, how air shed resources are managed in constrained air sheds. Secondly, how financial modelling is used to value air quality constraints, and thirdly, how a rigorous and comprehensive e-learning course is used to improve the overall level of air management knowledge of Rio Tinto?s environment managers.

Feb 27, 2013

By Xinghai Lei, Nan Wang, Xiangyang Jin, Yuqi Ren, Yang Li

The upward mining method, as an effective mining method, is widely employed in close-multiple coal seams to extend the service life of coal mines and improve the recovery rate of residual coal resources. However, the upward mining feasibility of the upper coal seam is related to the height of caved zone of interlayer strata after lower coal seam extraction. Therefore, it is extremely important to determine the height of the caved zone after the lower coal seam. The No. 9 coal seam (upper coal seam) and the No. 12- 1 coal seam (lower coal seam) in the Qianjiaying coal mine are selected as the research object. The characteristics of the interlayer strata structure field, fracture field, and subsidence field are studied using UDEC numerical modeling, in which the height of the caved zone is gotten after the No. 12- 1 coal seam extraction. Furthermore, the height of the caved zone is verified by onsite detection of GPR and BTVI. In the numerical modeling, the height of the caved zone is 19.6 m. And the height of caved zone is 14.7 m and 15.4–21.2 m, respectively, by using the onsite detection of GPR and BTVI. The heights of the caved zone onsite detection results are consistent with the numerical modeling result. The No. 9 coal seam is always located above the caved zone after the No. 12- 1 coal seam extraction. Consequently, the upward mining of the No. 9 coal seam is feasible.

Jun 28, 2023

By Francis J. Quinn

The Natural Gas Act, of 1938, which put interstate pipelines under the jurisdiction of the Federal Power Commission, did not place a protective competitive shield around such companies - nor does any provision of the act guarantee them a profit. Natural-gas pipelines are competitive with each other and also with the coal and oil industries. Gas distributing companies must compete not only with the coal and oil industries, but also with the electric industry. Natural gas has captured markets from oil, which had taken them from coal. Oil men contend that gas prices have: been, held to an artifically low level by regulation. The electric industry is moving into the space-heating market, which pleases the coal people because the coal industry's largest customer since losing the railroads to dieselization has been the electric companies. The coal industry is attempting to monopolize the industrial and electric generating market through government intervention, and this is being done under the guise of concern for the national welfare through advocation of a "National Fuels Policy purporting to, further the cause of fuel conservation. Such a policy is contrary to American principles and would result in the individual's loss of freedom of choice and ultimately, in less reserves of preferred fuels because of diminished exploration efforts.

Jan 1, 1961

By Miguel Reyes, Bruce Whisner, Joseph Bickson, Lincan Yan, David Yantek, Justin Srednicki, Nicholas Damiano, Eric Bauer

Built-in-place (BIP) refuge alternatives (RAs) are designed to provide a secure space for miners who cannot escape during a mine emergency. Heat and humidity buildup within RAs may expose miners to physiological hazards such as heat stress. To minimize the risk of heat stress, Title 30 Code of Federal Regulations (CFR), or 30 CFR, mandates a maximum allowable apparent temperature (AT) for an occupied RA of 35 °C (95 °F). The National Institute for Occupational Safety and Health (NIOSH) has conducted extensive research on the thermal environment of occupied RAs intended for use in underground coal mines. NIOSH research has demonstrated that a fully occupied BIP RA can exceed the AT limit by more than 5.6 °C (10 °F) in mines with elevated mine strata and air temperatures. In this circumstance, an RA cooling system could provide a solution. This paper provides an overview of test methodology and findings as well as guidance on improving the performance of a cryogenic air system prototype by optimizing the flow rate, increasing the tank storage capacity, and improving the efficiency of the heat exchanger of the cryogenic system. This may enable BIP RAs to meet the 35 °C (95 °F) AT limit in mines with elevated temperatures. The information in this paper is useful for RA manufacturers and mines that may choose to implement a cryogenic air system as a heat mitigation strategy.

By R. E. Hamilton

It is more than ten years since the first fully automated process using a computer started operation. Computer control has become common in a number of process industries, yet in spite of the tremendous incentives which ere present, there are only a few computer installations in the mining industry and none of these has announced successful control of a process. Recognizing that one of the reasons for this slow progress is the lack of adequate mathematical models of the various processes involved, the author's company started a project in the summer of 1966 to develop such models. It was early recognized that the existence of a major disturbance input, in the form of the mineral composition of the feed prevents most flotation plants from attaining a steady state condition. This makes the custom¬ary method of developing correlations from steady state plant data inapplicable and requires a more fundamental approach.

Jan 1, 1968

By Sheridan A. Glen

As the Federal government along with individual states continue to grapple with the job of refining a comprehensive energy policy, coal continually stands out as an energy source which heralds a combination of old and new capabilities like an energy planners prophecy, but which is plagued with serious environmental constraints. To determine what level of coal utilization is ultimately possible for states East of the Mississippi, whose high sulfur content coal presents the most paramount of challenges, one must consider product availability, via existing transportation modes, the developing industrial markets and the ability of coal to meet the challenge of becoming an environmentally acceptable fuel. Gasification is emerging as a form of utilization, which during the next twenty years stands a good chance of being able to meet the challenge of making coal an environmentally clean, easily transport-able and usable fuel. It can be argued that, of all the potential ways of utilizing high sulfur coal, coal gasification is perhaps the most expensive, the most financially risky and carries environmental liabilities of its own. Synthetic gas and oil markets will undeniably be a function of price and demand, which, for the purposes of this paper, I'm assuming will begin to merge in the late 1980's and into the 1990's. This is also presuming that public utility commissions will allow favorable price structure ruling so that gasified coal products can be rolled into their respective rate base, much the same as synthetic natural gas from petroleum by-products are currently being priced. The comparative economic markets of coal to gas pro-duct have plenty of time to mature. There is an approximate twelve-year lead time needed to bring coal gasification plants on line which will be able to compete in the market place for natural gas and oil customers.

Jan 1, 1977

By James Paone

Drillability of rocks by mechanical means is closely related to the physical properties of the respective rocks, Various approaches by previous investigators on rock drillability are presented, as well as recent techniques studied by the Bureau of Mines. The studies show drillability concepts based on (1) theoretical drilling equations derived from laboratory drilling experiments extended to field drilling results and on (2) a statistical method where multiple regression analysis is used to develop a prediction equation for drillability.

Jan 1, 1966