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By Marina Nicolova, Irena Spasova, Plamen Georgiev, Stoyan Groudev

Different strains of "silicate" bacteria were used to improve the quality of kaolin by different ways of treatment. All strains formed large slimy capsules consisting of exopolysaccharides and were related to different species of the genus Bacillus, mainly to B. circulans and B. mucilaginosus. It was found that even a short contact of some hours of well developed cultures of these bacteria resulted in improvement of the bending strength and the other ceramic properties of the kaolin. The improvement was connected with the action of some secreted microbial metabolites such as soluble heteropolysccharides, monosugars and organic acids. The best results were achieved by continuous cultivation of bacteria in the presence of kaolin with a high relative humidity and subjected to periodic stirring.

Jan 1, 2014

By A. P. Gentsch

Commercially mined calcium carbonate is normally found near the surface in the United States. It is nun& either by open pit or underground methods, depending upon its geologic setting. Processing ranges from simple crushing to the more sophisticated ultrafine processes. Intermediate steps are pulverizing, screening, beneficiation, classification, fine and ultrafine grinding, and surface treating. These processes are performed both dry and/or wet resulting in powdered or slurry end products.

Jan 1, 1986

By L. Donovan Clark

The term "powder factor" is almost universally accepted as the measure of the efficiency of a blasting program. It represents the economics of blasting since it designates quantity of explosive (thereby providing quality control in rock fragmentation) in terms of the associated volume broken. It is the wide use of this concept that explains the interest shown in an approach to rock blasting preferred by A. W. and Z. W. Daw* in a treatise on 3 blasting (1) substantiating its use in the form, Q = CVW3 for single shot hole, where Q = quantity of explosive lb Cv = blasting coefficient W3 = unit volume of rock It is obvious that the term Cv could also be called the apparent powder factor should the equation be written in the form, Cv = Q/W3 (lb per cubic unit). However, while the approach was ingenious** and the practical applications straightforward, their original, rather limited experimental work, along with certain assumptions, was questioned.

Jan 1, 1970

E. Windsor Richards, London, England:—In reading this paper the most interesting point to me mas the question of the maximum percentage of phosphorus allowable in the steel rail. Mr. Colby said, and we will all agree with him, that the engineer knew, and even a steel-rail maker grants that phosphorus is the most undesirable constituent of steel. We in England have been for a long time considering a specification for the supply of steel rails. This matter has been taken up by the Institution of Civil Engineers, the Mechanical Engineers, the Iron and Steel Institute, the Institute of Naval Architects, and the Electrical Engineers. Committees have been formed,and the whole matter has received most careful attention. They arrived at last at an analysis which I will read: " The carbon is to be from 0.35 to 0.5 per cent.; the manganese from 0.7 to 1.0 per cent.; the silicon, not to exceed 0.10 per cent.; phosphorus, 0.07; and sulphur, 0.07 per cent." As to the phosphorus, which is the most important point of all in the analysis, we have for many years, and indeed until very lately, always agreed to supply steel which would not contain above 0.06 per cent. of phosphorus. Iron-ores are not quite as good now as they were formerly, and the manufacturers at the meetings of the committees referred to, tried to obtain an increase in the allowance of phosphorus. They asked the Sub-committee to agree to 0.08 per cent. of phosphorus. They tried all they possibly could to obtain that; but they failed. English engineers in Great George Street and all over England, representing the important Associa tions I have mentioned, would only agree to 0.07 per cent. and that is the maximum allowance of phosphorus. Mr. Colby is an able advocate, but with all his ability he would not have been able to persuade the English engineers to agree to 0.08 per cent.

Jan 1, 1907

By M. Drozd, A. Ibrado, P. Butcher

While effective in treating refractory sulfide ores, pressure oxidation leaves carbonaceous matter unscathed and able to adsorb gold from cyanide solutions. Barrick Goldstrike's strategy to mitigate this problem is to minimize contact between dissolved gold and native carbon in advance of the carbon-in-leach (CIL) process. Measures currently in use include limiting carbonaceous matter in the plant feed by meticulous blending of ore, controlling the degree of oxidation in the autoclaves and blinding native carbon surfaces with lauryl sulfate. The presence of residual cyanide and thiocyanate in the process water remains to be a cause of premature gold dissolution and loss of gold by adsorption on carbonaceous matter. This cyanide is introduced by water that is recycled from the tailing pond. Of several treatment options considered, oxidation by peroxymonosulfuric acid, also known as Caro's acid, is deemed to be the most effective. Laboratory and pilot plant tests show that Caro's acid can oxidize free cyanide, weak¬acid-dissociable (WAD) cyanide and thiocyanate, resulting in significant improvements in gold recovery downstream. The process requires Caro's acid at 125 % of the stoichiometric requirement and pH in the range of 9.5 to 10 to accomplish the desired destruction in about twenty minutes. A cyanide destruction plant is currently being designed and construction should be completed by the end of 2005.

Jan 1, 2005

By J. O. Claassen

"A study conducted at 22 operating mines in the southern African region indicated that each mine employs about five management and improvement methods with roots in the manufacturing industry. All respondents reported the implementation of cost-saving initiatives, whereas 80% of the mines are affected by restructuring. TQM, Six Sigma, BPM, and TOC were found to be the most prevalent manufacturing management and improvement methods used. A mechanistic vs systemic evaluation of the suitability of these methods to bring about positive change in the industry suggested that complex, ever-changing mining systems are better served by a systemic flow-based approach, which is embedded in methods such as TOC, JIT, TPS, and Lean Production. These methods, however, lack industry presence, possibly because they do not effectively deal with the unique challenges associated with the mining environment. It is argued that successful mining business management and improvement depends on management’s ability to deal effectively with mining industry-specific requirements, the integration of the geologymining- plant system, and the implementation of systemic flow-based principles in all aspects of mining. IntroductionThe study aims to explore the use of manufacturing management and improvement methodologies in the southern African mining industry. Considering the unique challenges associated with mining operations, attention is given to the applicability of the most commonly used manufacturing methodologies in the tactical, operational, and strategic environments. The article endeavours to stimulate more research and debate in an unexplored field of study."

Jan 1, 2016

By Holmes RJ, Sowerby BD, Watt JS

Major improvements have taken place in mineral and coal processing in the last decade. The development of nuclear on-line sensors that continuously analyse the material being processed has led to better control of metalliferous mineral processing and increased recovery of valuable minerals. The recent development of on-line techniques for analysis of coal is expected to be of similar Importance. Australian developments in on-line nuclear gauges are reviewed. These include systems for in-stream analysis of mineral slurries with comments on plant operating experience; on-line determination of ash in coal using low energy Y-ray transmission and pair production techniques; in-stream determination of solids weight fraction and ash content of coal in slurries with variable voidage; and on-line determination of moisture in coal, iron in high grade iron ores and sulphur in lead sinter.

Jan 1, 1986

By Linney, Robert J.

REPUBLIC Steel Corporation's iron-ore properties in the Adirondacks consist of mines, mills, and sintering plants in the Mineville and Port Henry area and at Lyon Mountain. This article will deal with the properties in the vicinity of Mineville and Port Henry. In 1938, when Republic leased the Mineville- Port Henry operations from the Witherbee Sherman Corp., these properties had just come through some hard depression years. As a result, the mine development program was far behind schedule; most of the equipment needed replacement; and above all, the entire system of mining had to be completely changed to reduce operating costs. The concentrator had been in operation for many years; the process was dry and dusty. Machinery and equipment were either badly worn or entirely obsolete. The sintering plant, also long in operation, was badly in need of repairs.

Jan 1, 1943

By Glenn A. Hazen

This report presents a stress investigation of four coal pillars located under two depths of cover. Each coal pillar was instrumented with ten load cells designed to measure coal pressure during initial and secondary mining. The problem considered was one of uniform triaxial stress as a large coal pillar was loaded under a thick limestone bed. Special attention was given to pillar design procedure. Unconfined uniaxial compression tests were conducted for coal specimens 7/8 in., 2-1/8 in., 3 in., and 4 in. square with length to square side ratios of 1/2, 1, 1-1/2, and 2. Stress-strain curves were recorded. Six specimens were tested at each size. Results show that a coal pillar is composed of an inner zone which is highly loaded plus a region around its perimeter which has lost its elastic strength. The bearing capacity of a coal pillar consists of elastic and crushed coal response: The failure strengths have been determined and will be useful in coal recovery, mine design, and mine safety.

Jan 1, 1975

By G. W. Birge, D. E. Wolfson, J. H. Lynch

This report presents all available 900 ° C BM- AGA carbonization and related data for coals from the principal beds of the southwest Virginia field in a form which permits ready comparison of product yields and properties of coals and cokes . Thirty- one channel samples from Buchanan , Dickenson , Russell , Tazewell , and Wise Counties were carbonized at 900 ° C in an 18 - inch - diameter retort . Blending properties of 10 of the coals were studied , and expansion of most of the coals and blends was measured in the Bureau of Mines sole - heated oven . Ash Most of the samples were chemically suitable for metallurgical use in coking blends , and their coking properties generally were satisfactory . content exceeded 10 percent in only three samples , and none of the coals contained more than 1.5 percent sulfur . Dry , mineral - matter - free fixed - carbon content of the coals ranged from 62.1 to 77.5 percent . Expansion behavior varied widely , ranging from 16.8 percent expansion to 27.6 percent contraction .

Jan 1, 1964

By V. M. Torres

An empirical correlation to detennine laboratory mill grinding time has been developed. Grinding samples to 90 ± 5# below 147 micrometers was required for a flotation testwork at Companhia Vale do Rio Doce (CVRD) Research Center. The initial samples were all below 1 mm in size with different size distributions and work indices (Wi) ranging from 13 to 23 kWh/st. Grinding curves were determined for some initial samples. A correlation was developed between percent retained on 147 micrometers at a standard time and the time required to grind each sample to the required size. This correlation was then used to grind all samples, based on the preliminary grinding model. Finally, a statistical analysis with the size distribution of all samples was performed. The success of using the correlation was confirmed and an equation was determined using the data set.

Jan 1, 1996

By Ximena Diaz

Mercury is one of the most undesirable contaminants in gold bearing ores. During cyanidation mercury cyanide compounds accompany gold in all the extraction and recovery processes. Of course mercury in the carbon eluates creates environmental problems in subsequent refining steps. One possible process alternative for the separation of gold from mercury in such concentrated alkaline cyanide solutions is the selective solvent extraction of gold by undiluted Dibutyl Butyl Phosphonate (DBBP). In order to describe the behavior of mercury during extraction by DBBP, the results from a preliminary research program are presented. In this study, temperature and cyanide concentration have been found to be the most significant variables which influence the separation of gold from mercury by solvent extraction using DBBP. It was found, using plant eluate from a carbon strip, that excellent separation of gold from mercury can be obtained at 60' C with 98% gold recovery and complete mercury rejection in a single stage of extraction. The influence of pH is also discussed in terms of the extraction chemistry. These results complement previous research which described the DBBP solvation extraction of an aurocyanide ion pair. In addition, these results extend our understanding of the alkyl phosphorous ester extraction systems by illustrating that neutral ionic species such as Hg(cN)02sq, can be extracted at low cyanide concentrations, a phenomenon which had not been observed previously for other cyanoanions.

Jan 1, 1993

By E. H. Denny

The presence in the Cripple Creek district, Colo., of irrespirable gas or gases, generally known to consist mainly of nitrogen and carbon dioxide, has been recognized by members of the mining industry in that region almost since underground mining was begun there; the occurrence, origin, and possible control of these gases have been discussed in several articles cited at various places in this report. Similar gases have also been studied in other metal-mining districts, as later discussed. In March, 1925, there were two fatalities from rock-strata gases in the shaft of the Index mine, near Cripple Creek. Two men repairing the bell or signal line preparatory to reopening the shaft were lowered into irrespirable gases and died. Their bodies were recovered by rescue crews from the United States Bureau of Mines and .the Portland mine, Victor, Colo. These crews found it necessary to use oxygen breathing apparatus. In October of the same year a miner was trapped on the 6 level of the Midget mine by an influx of gases that filled the shaft to a point above that where he was working. Oxygen breathing apparatus was again used by Bureau of Mines employees, who were in the vicinity, and the man was brought out in time to save his life. These two fatalities and one near fatality seemed to show that additional investigation of the gases and methods of control might be warranted. Accordingly, field and laboratory studies were begun by the authors of this report after a visit to the district by M. van Siclen, then engineer in charge, mining research division, Bureau of Mines, and after conferences with the Mine Owners' Association of Cripple Creek and with J. T. Joyce, metal-mine commissioner of the State of Colorado. The mine operators of the Cripple Creek district and the State mine commissioner's office gave whole-hearted cooperation in this work.

Jan 1, 1930

By Shanjun Mao

This paper summarizes current achievements of Digital Mining in China, puts forward the concept, framework and key technology of Smarter Mining, and finally points out that there is still a long way to go in order to acheive Smarter mining.

Aug 1, 2013

By J E. Wajon

This paper discusses the background, requirements, need and content of plans for management of drinking water self-supplied to mining-related operations, including construction camps, especially in remote areas of Western Australia. The paper discusses the importance of cooperation between regulators, the mine site operator and the consultant in preparing a plan fully compliant with the Australian Drinking Water Guidelines to protect the quality and safety of drinking water supplied to mine sites. The paper outlines some of the issues that need to be addressed in preparing a drinking water quality management plan, such as hazard identification, risk assessment, the multiple-barrier approach and the concept of critical control points. Data requirements, monitoring, incident management, training and reporting are also covered.CITATION:Wajon, J E, 2013. Drinking water quality management for mining operations in Western Australia, in Proceedings Water in Mining 2013 , pp 321-328 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Nov 26, 2013

By C Carbonneau

In order to successfully produce columbium pyrochlore concentrates, St. Lawrence Columbium and Metals Corporation had to face two principal problems met in several new operations but possibly made more acute than usual owing to the newness of the project. 1.-The ore is particularly complex, as it is made up of an elaborate intermingling of carbonates and discontinuous ultra-alkaline rock bodies of various ages and types in which no less than seventy mineral have been re-ported. Obvious petrographic or structural controls are lacking. Ore boundaries have to be defined on the basis of assay results and the determination of several minerals which occur in trace amounts. 2.-The pyrochlore concentrates produced had to com-ply with a set of stringent specifications. This fact, combined with the low Cb205 content of the ore, necessitated the use of a beneficiation process that would have to operate at a concentration ratio greater than 100:1. A brief description of the mill circuit is given. Mill stability was obtained through extensive mineralogical study of the mill feed coupled with close geological and engineering control of the mining operations.

Jan 1, 1965

By J. D. Clendenin

Systematic practices for protecting crops from frost damage began in the United Metes more then 40 years ago when the Weather Bureau Fruit-Frost Warning Service was organized; however, various practices employed in frost protection are centuries old. Although there are areas where little doubt exists as to whether protection is needed, there are also circumstances where there is some doubt as to the need for frost protection. Many factors influence this, including not only critical temperatures but also the maturity dates of the crops relative to marketing. Critical temperatures for frost damage to trees, plants, blossoms, and fruits very with weather, plant variety and nutrition, and stage of growth. In the case of truck crops, a single night of protection from frost injury might yield big dividends with a variety of sweet corn or tomato that matures early while price is high yet be worth very little with a midseason or late-maturing variety. Consequently, it is the individual grower who must decide whether to use frost-protective measures on the basis of his returns, the quantity and quality of his crop, the marketing situation, the sensitivity of his crops to frost damage, and the frequency of damaging frost in his area.

Jan 1, 1955

By N Dube, K L. Sandvik, C Mutevhe

Trojan Nickel Mine is the largest producer of Ni, Cu and Co in Zimbabwe. The mine has operated a nickel flotation concentrator and base metal refinery continuously since 1969, creating 28 million tonnes of sulfide bearing tailings, five million tonnes of permanent waste rock and about seven million tonnes of smelter slag. Exposure of the sulfide bearing minerals renders them susceptible to oxidation in the presence of water and oxygen, resulting in acidic solutions with elevated concentrations of total dissolved solids, sulfate, metals and residual flotation chemicals in various waters draining from the mine site. These pollutants pose a direct threat to the environment and human health, and understanding their deportment and behaviour in the various waste streams is essential in the mineÆs environmental objectives to prevent or minimise adverse impacts arising from its operations. A geochemical assessment of the pollutants was carried out to compute a mass balance between the major sources of pollution and the distribution and fate of pollutants in waste streams from the mine site. Waste rock, tailings, surface water, ground water and sediments were sampled, tested and analysed. Mineral composition and water chemistry data show that geochemical reactions are responsible for the release of pollutants from waste rock, tailings and plant spills. Drainage from the mine area is near neutral due to buffering by magnesium carbonates in the fine fraction of the tailings. The natural wetlands that exist downstream of the waste rock and tailings dams are effective in reducing metal loadings to water courses. However, solutes and heavy metals are occasionally released to surface and ground water, when their concentrations peak during the dry season. The results demonstrate the necessity to understand the natural chemical processes that characterise the distribution of pollutants in nature and how such knowledge can be used to develop cost effective methods to remediate pollution in the natural environment.

Jan 1, 2006

By S. M. Molloy

The postwar demand for insulating material such as mineral wool, in-creased in proportion to the rapid construction of new buildings, placing an enormous burden on the existing mineral-wool industry both in known sources of raw materials and in available plant facilities. In view of the increased demand on the industry, the Bureau of Mines in its Mississippi Valley Experiment Station" Rolla, Mo., undertook an investigation to aid the industry by establishing resources of raw materials through actual laboratory wool-blowing tests and by developing certain methods for evaluating the physical proper-ties of a mineral wool. As material was received from the public, laboratory-evaluation technique had to be developed, the results of which would reflect in the mineral-wool-industry standards. The methods of testing used by the mineral-wool industry, not only would have required a pilot-plant installation capable of producing a large tonnage of mineral wool, but each wool-blowing campaign would have been very expensive and necessitated considerable personnel and equipment. The present laboratory wool-blowing equipment can produce as high as eight wool-blowing campaigns a day. The nature, simplicity, and size of the physical testing equipment permit testing as small a sample of wool as 25 grams and give information as reasonably accurate as in a 40-pound bag of wool. The purpose of this report is to describe the laboratory method of production and the evaluation of the physical properties of small quantities of mineral wool. Considerable work has already been done, and the interest of the public and industry is measured in the number of samples being submitted for testing.

Jan 1, 1948

By D. Harrington

This circular presents part I of a review of the literature on effects of breathing dusts, with special reference to silicosis, largely in the minim; and allied industries. The literature on this subject is so extensive that no attempt has been made to include all published material but only to assemble some of the more outstanding data on several aspects of the subject. Parts II and III will deal with prevention and treatment of dust diseases and some of the economic and legal aspects of dust diseases in industry, with special reference to mining. Dust diseases arc much before the public at present, and there is good reason to believe that the information on the subject available to the layman is extremely meager; even those rated as experts usually have a more or less theoretical conception of the diseases, their causation, remedies, and prevention, rather than actual experience with them. Until recently little attention has been given to prevention, and the usual attitude of the engineer, upon whom the main reliance for prevention ultimately must devolve, has been to let "sleeping dogs lie" or, more definitely, to "let well enough alone." However, the "laissez faire" attitude no longer is tenable, and in the past few years numerous conditions have caused those engaged in industry, including mining, to bring the subject before the public with a view to ascertaining the facts upon which to formulate remedial measures, primarily preventive.

Jan 1, 1935