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By V. F. Parry, W. S. Landers

"INTRODUCTION The primary object of this investigation was to determine changes in physical and chemical properties of subbituminous lump coal while in storage for 8 months in a typical residence and to demonstrate how this fuel may be stored without degradation or spontaneous combustion. The second object of the study was to determine how the stored coal performed in a hand-fired furnace operated under practical conditions.The investigation revealed that if care is exercised in placing sub-bituminous lump coal in a closed bin, no significant slacking or degrada¬tion occurs, no hazards arise, and over-all indicated efficiencies of about 65 to 69 percent can be obtained under practical,firing conditions that the average home owner can meet.Owing to the war emergency, much attention is being given to the proper storage of coal, and campaigns are being conducted to increase the quantity of coal being stored to relieve transportation and production overloads. Ordinarily, coal dealers do not recommend storage of subbituminous coal in homes owing to deterioration of the coal and to possible hazards from spontaneous combustion. This practice has grown from some troubles that have been experienced, which can be traced to improper preparation, improper bins, and poor technique in placing coal in a bin. There is no good reason why subbiturninous lump coal cannot be stored safely in homes."

Jun 1, 1944

By Kirsi M. Riihilahti

The oxidation characteristics of solid copper matte particles under simulated Kennecott-Outokumpu Flash Converting conditions are presented. This project is concerned with the determination of the effects of operating variables on the reaction of the particles. Experiments were carried out in a large laboratory-scale flash furnace with 72 wt-% Cu matte by varying initial particle size, temperature, oxygen partial pressure, oxygen-to-matte mass ratio and residence time. Chemical analysis was used to study the oxidation extent and copper volatilization. Particle fragmentation was examined. Fractional conversion and sulfur removal slightly decreased with initial particle size, while a higher oxygen-to-matte mass ratio mainly resulted in higher fractional conversion and more efficient sulfur removal. The fractional conversion values represented the overall extent of oxidation more closely than degree of sulfur removal.

Jan 1, 1997

By Manuel Llosa Pautrat

El presente estudio señala la interpretación de los balances de una empresa minera de acuerdo con las disposiciones legales existentes y la práctica establecida en el país. En esta interpretación de balances se ha utilizado ciertos índices como el de balance general, cuenta de ganancias y pérdidas, balance con las ganancias y pérdidas, origen y aplicación de fondos, donde la experiencia resulte de mayor utilidad en el análisis de compañías mineras. Dentro de los índices de balance general están las fuentes del capital, distribución y la inversión del mismo. Entre los índices que analizan la cuenta de ganancias y pérdidas está el control de costo y resultados de la operación. Los índices que relacionan el balance con las ganancias y pérdidas son los coeficientes de rotación, rotación de inventario y distribución de los accionistas. Finalmente, el índice del origen y aplicacíón de fondos, indica la procedencia de los nuevos fondos ingresados en el ejercicio considerado (origen) y hacia dónde se destinan (aplicación).

Aug 20, 1963

By H Ishikawa, R Halomoan, S Palaniandy

The Karara iron ore project is a magnetite operation consist of open pit mining and concentrator to produce high-grade magnetite concentrate. The concentrator has adopted three stages of comminution, ie fine crushing in the high pressure grinding rolls (HPGR), primary ball milling and fine grinding in the TowerMill plus magnetic separation in between these comminution devices. Since 2014, the concentrator has increased the plant feed rate by 18 per cent. Meanwhile, the ore hardness has increased by 13 per cent to a Bond work index value of 15 kWh/t that led to a coarser flotation feed. Karara Mine has decided to shift the comminution workload from the primary ball mill to the TowerMill circuit by bypassing the 100 µm fine screen in between the ball mill and TowerMill circuits. This action has increased the circuit feed particle size distribution with a top size close to 1 mm. The specific energy consumption of the TowerMill circuit was approximately 3.4 kWh/t, and the circuit product sizes (P80) were ranged between 38 and 45 µm. A joint process improvement exercise was carried out to reduce the circuit product size closer to the magnetite liberation size, ie 35 µm. Among the activities were circuit audit, recommendation for improvement, modelling and simulation, multicomponent analysis, implementation of recommendations and quantification of the improvement. One of the key findings was the density effect of multicomponent minerals in the hydrocyclone. The analysis revealed that the low density coarser gangue minerals were bypassed to the hydrocyclone overflow stream that has resulted in a coarser particle size distribution. Meanwhile, more than 20 per cent of fine (-35 µm) high-density magnetite particles were recycled back to the mill through the hydrocyclone underflow stream and increased the circulating load. Based on these outcomes, several recommendations such as conversion to bottom feed configuration, use of smaller grinding media, high operating hydrocyclone pressure and additional grinding power to the TowerMill circuit were made to improve the overall circuit performances. Karara Mine has prioritised to implement those recommendations that have a minimal financial implication. Full-scale plant trials with bottom feed configuration and 17 mm grinding media were conducted to evaluate its performances. These trials have indicated that the grinding efficiency in the TowerMill was enhanced by 10 – 30 per cent. In May 2017, all the five TowerMills were converted to the bottom feed configuration. This paper discusses the impact of shifting the comminution workload load from the primary ball mills to TowerMill circuit and the performances enhancement of the TowerMill circuit. CITATION:Palaniandy, S, Halomoan, R and Ishikawa, H, 2018. Shifting the comminution workload from the primary ball mill to TowerMill circuit, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 163–176 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

Through a contract, the Bureau of Mines has funded the development of an Automated Breathing Metabolic Simulator (ABMS). The ABMS simulates man in all of the breathing and metabolic parameters for monitoring support and resuscitation equipment. For the first time, complete breathing and metabolic simulation are incorporated in the same device. Breathing rate, breathing depth, breath velocity contour, oxygen uptake, and carbon dioxide release are all variable over wide ranges, simulating conditions from sleep to hard work with respiratory exchange ratios covering the range of hypoventilation to hyperventilation. In addition, all of these parameters are remotely controlled to facilitate the use of the device in hostile test environments. The exhaled breath is also at body temperature and completely saturated. The simulation in faith¬ful to the extent of having a variable functional residual capacity and an anatomical dead space equivalent to that of humans. The ABMS will be used as a stand-in for humans in test and validation of respiratory equipment, permitting more extensive and safer evaluation in hazardous environments where human testing would have to be limited. In addition, it will greatly reduce the cost of prolonged testing in cases where simulation chambers with human subjects require three shifts of crews, including standby physicians. Perhaps most importantly, it will provide a calculated and reproducible test and validation facility. The ABMS is under complete computer control. Through a typewriter terminal the test sequence can be input into the computer which will then automatically adjust the ABMS to simulate any desired sequence of metabolic activities for time durations up to 15 hours. The computer also monitors the test procedures and provides test results printout.

Jan 1, 1973

By R M. Arellano, D M. W Harney, M Makhuvha

Mineral resource and ore reserve estimates are founded on two sources of data: tonnage and grade. The tonnage is a product of volume and density; both of which are estimates. Density impacts numerous operational factors, which include, but are not limited to, mine design, mine planning, equipment selection and operational performance. Hence, density is a significant parameter and its determination requires similar care as the measurement of grade. Selecting an appropriate method to determine density, and ensuring its rigorous application, thus reduces risk and can improve operational performance, which in turn increases profit margin.Different Anglo American sites use a variety of practices and protocols to determine density, which is highly dependent on the physical characteristics of the orebody, local conditions and historical practices. Also, individual sites sometimes execute the same method in a slightly different way, which may also affect the outcome of the measurements. In order to gain a better understanding of how density is determined at Anglo American projects and operations, a review of these techniques was undertaken. The objective of the study was to identify and share good practices across the company, as well as to look for improvement opportunities, where applicable. Ten different methods of measuring density, applied to nine different commodities, were identified and described. An additional technique was recently developed by Anglo American Technical Solutions. The core pycnometer is a large gas displacement pycnometer capable of measuring density at high accuracy on full pieces of intact core.This paper provides an overview of methods used to determine density within the Anglo American Group, including quality control and quality assurance aspects. It is not the purpose of this paper to identify a preferred method, but to highlight the importance of choosing the best suited practice for a project or mine site. In addition, a case study comparing two different density determination methods applied to the same rock samples from the Los Bronces Copper mine was undertaken and the results of that study are presented here.Selecting the most appropriate method to determine density and comparing results from two or more techniques against each other, together with other suitable quality control procedures, is considered to be of utmost importance for all mining operations and exploration projects.CITATION:Makhuvha, M, Arellano, R M and Harney, D M W, 2014. Determination of bulk density in Anglo American plc, methods and impacts, with a case study from Los Bronces Mine, in Proceedings Ninth International Mining Geology Conference 2014 , pp 85–96 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 18, 2014

By Gerald W. Elger

This report compares the quality of zirconium metal prepared by batch reduction of zirconium tetrachloride by (1) sodium, (2) magnesium, and (3) mixtures of sodium and magnesium. Criteria for quality are based on chemical analyses and hardness testing of zirconium arc-melted from sponge. The best quality zirconium with respect to low oxygen content and hardness numbers was prepared by reaction of zirconium tetrachloride with a mixture of sodium and magnesium. It was found that this reaction could be successfully carried out by two methods: (1) addition of sodium and magnesium before the initial reaction and (2) periodic injection of sodium during reaction of zirconium tetrachloride with magnesium. The largest quantity of metal was found to be recovered from experiments in which a mixture of sodium and magnesium was used. Magnesium appeared to be a better reductant than sodium because magnesium-reduced zirconium contained less oxygen and exhibited lower hardness numbers than sodium-reduced metal.

Jan 1, 1962

By Launa G. Mallett, Charles Vaught, Dana C. Reinke, Lisa J. Steiner, Lynn L. Rethi, Kathleen M. Kowalski-Trakofler, Jr. Brnich, William J. Wiehagen

Safety and health professionals recognize that training is a critical element of any effective safety and health program. An extensive literature survey has led the authors to conclude that we are at the beginning of a revolution in training due to changes in the demographics of the workforce, the rapid growth of technology, and the universal ascendance of the information age. Of present major concern in the mining industry is how to provide appropriate training for an aging workforce and concurrently develop training for the expected influx of new and less experienced miners as older workers retire. This report explores the key issues in the changing safety and health training area as identified by the multidisciplinary team of NIOSH researchers who conducted the literature survey. Issues include generational differences between newer mine workers and the present workforce with respect to their physical, psychological, social, and cultural characteristics; their learning styles and work expectations; and the impact of technology. Some preliminary conclusions are offered for future training needs.

Jul 1, 2004

By W. D. Hausel

The Wyoming craton in the western United States is a favorable terrane for diamond deposits. The craton hosts a variety of ultramafic, ultrabasic, and ultrapotassic rocks. Additionally, a few hundred 'kimberlitic' heavy mineral anomalies and some geophysical and remote sensing anomalies indicate the presence of undiscovered, mantle-derived, pipes in the craton. The Wyoming craton is separated into a Wyoming 'archon' known as the Wyoming Province, and the Colorado 'proton' known as the Colorado Province. The 'archon' underlies much of Montana and Wyoming and continues north into Alberta and Saskatchewan; the Colorado 'proton' underlies much of Colorado and a small portion of Wyoming. Although most exploration geologists would consider the 'archon' the most favorable terrane for commercial diamond deposits, the 'proton' has produced more than 120,000 diamonds, while the 'archon' has not been very productive.

Jan 1, 1996

By G. A. Bezuidenhout, S. Bradshaw, W. Malan

"Currently, the matted-based collection process is most widely used for platinum group metal (PGM) recovery. However, because PGM-containing concentrates are becoming more enriched with UG2 (Upper Group 2) low-grade concentrates, this is expected to be integrated or replaced with an alloy collection process.The reduction LG (low-grade) concentrates with silicon carbide (SiC) was investigated. The purpose of the study was to ascertain the feasibility of using SiC as reductant with regard to metal fall, PGM grade in the alloy, slag composition, and overall PGM recovery, and if possible, the integration of such a process in the current matte-based collection process. Rowland and Easterns LG concentrate samples from Lonmin were analysed by Xray diffraction (XRD), X-ray fluorescence (XRF), and inductively coupled plasma mass spectrometry (ICP-MS). It was found that SiO2 and MgO are the most abundant oxides and Pd is the most abundant of the PGMs. Sulphide-bearing minerals such as chalcopyrite were detected in low concentrations (below 1%), and Cr2O3 concentrations are between 2-4%. SiC reduction of Rowland and Easterns concentrate were conducted at 1600°C with reductant to concentrate ratios ranging from 2.5 to 3.5 kg SiC per 100 kg concentrate.The reduction experiments revealed that PGM recoveries from Rowland concentrate were poor. SEM images showed entrained metal prills in the slag phase. The slag viscosity at the end of the melt was calculated by using FactSage, and the results indicated that the viscosity was higher than 4 poise, which is above that of Easterns slag. PGM recoveries for Easterns concentrate were significantly better. More than 85% of the Ir and Pd and almost 60% of the Pt were recovered in a test with a reductant to concentrate ratio of 3.5 kg SiC per 100 kg Easterns concentrate. At this reductant to concentrate ratio, Fe recovery was also the highest, at 66%. SEM imaging of a slag sample revealed few or no metal prills entrained. The FeO content in the initial concentrate charge was then increased by adding Peirce-Smith converter slag in order to decrease the slag viscosity and further increase PGM recovery. A test was conducted with the addition of 10 kg converter slag per 100 kg Easterns concentrate. The reductant to concentrate ratio was kept at 3.5 kg SiC per 100 kg Easterns concentrate. The Ir and Pd recoveries were more than 95%, while Pt recovery was almost 70%. Fe recovery increased to 76%. On the basis of these results an optimum feed ratio between Easterns and Rowland concentrates and Peirce-Smith converter slag were calculated. FactSage predicted that the concentrate charge should consist of 70-80% Easterns concentrate with 20-30 kg converter slag per 100 kg LG concentrate. SiC reduction of this optimum LG concentrate charge is expected to recover more than 90% of all PGMs. Cr and Si concentrations in the alloy will be below 1% in total.The effectiveness of SiC as reductant was also compared to carbon reduction. Carbon reduction of an optimum concentrate charge at the same reductant to concentrate ratio resulted in a marginally higher metal fall than SiC reduction. However, gas emissions and energy requirements are higher for carbon reduction.The study has shown that base metals and PGMs can be recovered in an iron alloy by SiC reduction of LG concentrate with converter slag additions. Integration of such a process into the matte-based collection process could be considered as a future alternative for smelting UG2 LG concentrates."

Jan 1, 2014

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 S. Mohammadnejad, M. Olizadeh, B. Mehrabi

A new method using a combination of comprehensive mineralogical and analytical approach which includes optical and electrical microscopy and several analytical techniques with diagnostic leaching has been used to characterize the associations and distribution of gold in a variety of minerals from the Zarshuran refractory gold ore, NW Iran. Zarshuran ore with an average of 7.9 g/t Au-grade and about 8% arsenic with gold recovery less than 20% in direct cyanidation is considered as high arsenic, high au-grade refractory gold ore. In most of the refractory ores, gold is associated with arsenopyrite and co-para genetic ore minerals, while in Zarshuran ore; gold is associated with orpiment, realgar and arsenian-pyrite. Considering its mineralogy and As content, it can be considered as the most difficult refractory ore for characterization and processing. Results from the mineralogical examination and diagnostic leaches indicate that there is only a small amount of free gold (17-19%) that is present in cyanide-soluble sulfo-arsenides compounds, predominantly orpiment and realgar. Diagnostic leaches also indicate that little gold is occluded within the silicate structure (14%). Overall, the gold is mostly included in sulfides, arsenic sulfides and sulfo-arsenides (50%). The results also have shown how the technique can be used to gain a good initial understanding of potential metallurgical problems for a refractory gold ore.

Jan 1, 2005

By L. R. Burdick

This paper presents a review of published investigation dealing with the importance of sulfur compounds in the deterioration of materials or providing some basis for estimating the extent of loss shareable to such air pollution. Materials included are cement, stone, metals, paint, leather, paper, sand cloth. The investigations may be divided into two classes, one of the laboratory type in which the sulfur content and the humidity of the air were controlled and the other dealing with the exposure of materials to atmospheres not under control. The first type of work has shown that cement is subject to deterioration by the action of sulfur dioxide gas. The experiments with stone indicate that although limestone takes up sulfur dioxide, from the air, moist sulfur dioxide-air mixtures alone cannot be used for establishing- the comparative weathering- qualities of the different types of stone by accelerated test methods. Laboratory tests indicate that sulfur compounds in the air accelerate the corrosion of iron, steel, zinc, copper, and nickel at normal air temperatures and at certain relative humidities. It has also been indicated that certain types of paint are, affected by high sulfur dioxide concentrations, and that paper is attacked by sulfur dioxide in the atmosphere. The investigations of the second type show the amount or variation of corrosion in different localities and under different types of exposure. The investigations (10) (18)4/ during which sulfur determinations were made indicate that sulfur dioxide is a main controlling factor in the corrosion of iron and steel but according to Quick (18) may not be for some nonferrous metals. In general, the laboratory tests do not Jive definite data on the loss due to sulfur compounds at the concentrations normally found in the air. The data from atmospheric exposures are not complete from the standpoint of the exact effect of the sulfur compounds. Damage to materials so exposed is affected by factors such as other chemical contaminants, humidity, rainfall, solid deposits, and sunlight. A simple scheme has been devised in Great Britain which is considered to provide a measure of the attack of sulfur compound, on building materials (1). Small cylinders coated

Jan 1, 1939

By S. H. Ash

The paramount responsibility of Government is to protect the general welfare. One of the chief functions of the Bureau of Mines is to investigate and publicize methods of increasing safety and efficiency in mining operations. In an industrial civilization, energy resources constitute the foundation of a sound economic structure (14).4/ Coal is only one source of energy, but it provides more than half the energy consumed in the United States.

Jan 1, 1946

By Ludwig Schmidt

This report, the second of a series, presents the results of laboratory corrosion studies which were made in connection with a one-year test on aluminum lease tanks conducted by the United States Bureau of Mines. Part 1 of the report contains the results of the field tests. The studies were made on an oil lease in a so-called "sour district," near Borger, Tex., where free hydrogen sulphide accompanied the production of oil, gas, and salt water. Steel tanks previously used on the lease had suffered severe corrosion, because steel is inherently susceptible to attack by hydrogen sulphide. Because of the high resistivity of aluminum to the action of hydrogen sulphide, it was believed that this metal had promising possibilities as a material for the construction of lease tanks in "sour districts." The results of the one-year field test proved that aluminum lease tanks will withstand corrosion by hydrosulphide, but it as found that aluminum was susceptible to attack by salt water, which was invariably present in certain portions of the tanks, and that hydrogen sulphide accelerated this salt-water corrosion in an indirect manner, as will be explained hereinafter. In order to study corrosion conditions encountered in the tanks during the test period, a laboratory was maintained at the site of the aluminum lease tanks.

Jan 1, 1931

By Thomas A. Phillips

This publication is an economic evaluation of the Bureau of Mines electrolytic process for recovering lead from scrap lead-acid batteries. In this process, scrap batteries are crushed and separated into metal and sludge fractions. The metal fraction is cast as anodes and electro- refined. Lead in the sludge fraction is converted to lead carbonate by reaction with an ammonium carbonate-ammonium bisulfite solution. The lead carbonate is then dissolved in a fluosilicic acid electrolyte from which pure lead metal is electrowon. A cost estimate is presented for a plant capable of processing 10,000 scrap batteries per day. The fixed capital cost for this plant is estimated to he $14 million on a fourth quarter 1984 basis. Operating costs are estimated to be $0.15/lb Pb recovered. Assuming a lead selling price of $0.17/lb, the interest rate of return on investment after taxes is 11 pct. A lead selling price of about $0.21/lb is needed to obtain a 20-pct-interest rate of return.

Jan 1, 1986

By Ravi S. Bellur-Ramaswamy, Daniel A. Tortorelli, Robert Haber, Nahil A. Sobh

We optimize continuous quench process parameters to produce functionally graded aluminum alloy extrudates. To perform this task, an optimization problem is defined and solved using a standard nonlinear programming algorithm. Ingredients of this algorithm include 1) the process parameters to be optimized, 2) a cost function: the weighted average of the precipitate number density distribution, 3) constraint functions to limit the temperature gradient (and hence distortion and residual stress) and exit temperature, and 4) their sensitivities with respect to the process parameters. The cost and constraint functions are dependent on the temperature and precipitate size which are obtained by balancing energy to determine the temperature distribution and by using a reaction-rate theory to determine the precipitate particle sizes and their distributions. Both the temperature and the precipitate models are solved via the discontinuous Galerkin finite element method. The energy balance incorporates nonlinear boundary conditions and material properties. The temperature field is then used in the reaction rate model which has as many as 105 degrees of- freedom per finite element node. After computing the temperature and precipitate size distributions we must compute their sensitivities. This seemingly intractable computational task is resolved thanks to the discontinuous Galerkin finite element formulation and the direct differentiation sensitivity method. A three-dimension example is provided to demonstrate the algorithm.

Jan 1, 2001

By K. C. Dean

During investigation of the occurrence of manganese deposits in the western United States, examining engineers of the Bureau of Mines collected samples from several properties in Montana. Extensive laboratory tests were made to determine the amenability of these ores to standard ore-dressing methods of concentration to produce marketable-grade products. The Tzarena claim, one of the properties sampled, is on the western end of the Rama or Black Chief vein in the city of Butte, Silver Bow County, Mont., on the southwestern periphery of the mining district. The Black Chief 'WAR system contains one of the largest and most extensive known rhodochrosite deposits in the world. Test work was conducted on two samples of Tzarena ore. Sample 1 is representative of a vain 5 feet wide on the 150-foot level of the Tzarena shaft. Sample 2 is representative of a vein 8 feet wide in the 100-foot level of the shaft. The Minnie Jane mine, 1/2 mile northwest of the Tzarena claim, contains ore similar in mineralogical composition to Tzarena ore but differing materially in manganese content and to some extent in physical characteristics. Ore-dressing investigations were made on three samples of Minnie Jane ore. Sample 1 represented stock-piled ore, sample 2 represented ore from Minnie Jane mine having a considerable sulfide content, and sample 3 represented low-grade ore.

Jan 1, 1951

By Rodger C. Smith

The topic chat has been assigned to me ?Economic and Political Climate of the Potash Industry? is a function of two basic facts: 1. Potassium is absolutely essential to plant and animal growth. Along with nitrogen and phosphorus it is one of three major plant nutrients, the three nutrients required in largest quantities for plant growth. 2. United States is unequivocally an "have not" nation with regard to potassium. Quantity of potassium ores is limited and, more disturbing, the cost of production at all U.S. potash mines is marginal in comparison with the major producing countries, i.e. Canada and U.S.S.R.

Jan 1, 1983

By D. J. MacDonald

As part of a U.S. Bureau of Mines program seeking improvements to the Bayer process, a typical Jamaican bauxite was heated at temperatures up to 500° C in hydrogen, and its leachability under Bayer process conditions was measured and properties of its leached residue were observed. The objectives were to find ways to decrease the amount of organic carbon in bauxite or in leach liquor derived from it without impairing its leachability, and to improve the leached residue's filterability. Techniques employed included heating bauxite under pressure in an autoclave with hydrogen, and in flowing hydrogen at ambient pressure in a tube furnace. Leaching tests were done with a 600-mL stirred reactor. In some of the leaching tests, ferrous sulfate (FeS04) was introduced before leaching to produce a partially magnetic product. Results showed that exposure to hydrogen at temperatures from 160° to 360° C progressively diminished the bauxite's content of organic carbon and decreased the ratio of organic carbon to aluminum in leach liquor, an improvement that would allow a process using hydrogen-treated bauxite to be operated at a smaller recycle ratio, thereby consuming less energy and allowing greater throughput for a plant of given capacity. The bauxite's leachability was not impaired by high-temperature pretreatments, except at temperatures higher than 280° C. Pretreatments in hydrogen produced black, partially reduced bauxite which upon leaching gave a residue that was attracted to a magnetic field and was amenable to separation from green liquor by a magnetic filtration method.

Jan 1, 2010