Search Documents

Silver and gold bearing ore from the Palmarejo mine, located within the Mexican state of Chihuahua, contains a complex mix of electrum, native silver, silver sulfides and silver chlorides. This paper presents a case study that describes the selection, development and engineering of a tailored process plant for the recovery of silver and gold from this ore. Process circuit feasibility study modelling, metallurgical test work and engineering studies are outlined. Options considered to optimise the recovery of the contained silver and gold are compared, based upon cost, operability, recovery and engineering aspects. Concentration by flotation was found to be the preferred primary recovery route. Intensive leaching of the flotation concentrate resulted in solution grades sufficient to allow direct electrowinning to be evaluated against the more traditional Merrill Crowe process. The flotation tailings stream is processed through a separate leaching stage as there is sufficient economic metal extractable from this stream. The processing flow sheet, which is designed to maximise the recovery from both the flotation concentrate and tailings, and to utilise a common metal production facility, is presented.

Jan 1, 2009

By Herbert H. Uhlig

ALTHOUGH the mechanical properties of high-carbon manganese-iron alloys, particularly the Hadfield manganese steels, have been established, the literature discloses discrepancies in the reported properties for the low-carbon alloys. Hadfieldlo summarized the existing data up to 1927, including the investigations of Guillet, Arnold, Strauss, Burgess and Aston, and reported his own values for alloys containing for the most part from 0.06 to 0.15 per cent carbon. He noted: From these comparisons it will be seen that while there is a broad and general agreement as to the character of the alloys at the different manganese percentages, there are disparities in individual cases, especially as regards the degree of toughness or brittleness displayed by an alloy with certain percentages and with particular types of treatment. These differences are not always readily explainable. Ib His data showed that alloys containing 4 to 10 per cent manganese water-quenched from 1000°C. were brittle and hard with maximum brittleness at about 7 per cent. Slight improvement in ductility was obtained with compositions from 10 to 17 per cent manganese. Alloys containing up to 17 per cent manganese slowly cooled rather than quenched from 870°C., he found, were slightly improved in ductility with significant improvement in alloys analyzing 4.1 and 4.8 per cent manganese. Recently Walters, Kramer and Loringa reported mechanical properties for alloys made up from electrolytic manganese and ingot iron and containing from 0.02 to 0.04 per cent carbon. They showed that a tempering treatment at 540°C. (1000°F.) for one hour significantly improved the ductility of compositions ranging from 6.7 to 20.7 per cent manganese. The differences of these compared with Hadfield&apos;s results they considered to originate in this tempering treatment plus the fact that Hadfield&apos;s alloys contained higher carbon and phosphorus (0.06 to 0.15 per cent C; 0.06 to 0.07 per cent P compared with 0.02 to 0.04 per cent C, <0.001 per cent P). In this paper it is shown that of the low- carbon alloys (0.02 to 0.03 per cent) containing from 3.3 to 21.5 per cent manganese moderately or rapidly quenched from 1000°C. some are brittle or ductile, depending on presence or absence of hydrogen. Hydrogen is readily absorbed at high temperatures, and much of it is retained when the alloys are cooled to room temperature. The presence of hydrogen in the range of composition from 10 to 18 per cent manganese is a major factor in determining relative ductility. At 22 per cent manganese, and also at compositions below 10 per cent manganese, factors other than or in addition to hydrogen play a role. These are discussed. Also data are presented to show that hydrogen absorbed by the high-carbon alloys of Hadfield composition is without effect on their mechanical properties.

Jan 1, 1944

By H. H. Kaveler

A summary of the reservoir engineering and related geologic data on the Schuler field, Union County, Arkansas, is presented here in a manner intended to interest both technical and nontechnical readers. The Cotton Valley formation and the Reynolds oolite are oil-productive formations in the Schuler field, but the Jones sand pool, at a depth of 7500 ft., developed with 146 wells on zo-acre spacing, is the reservoir of principal interest. The Jones sand sandstone reservoir is an anticlinal trap typically gas-drive or depletion type in performance. The core analyses from 88 per cent of the wells drilled, together with drilling time and electric-log data, yield an accurate estimate of the "productive" sand thickness and its areal distribution over the pool. Accurate production statistics, monthly reservoir-pressure surveys, and bottom-hole sample analyses when correlated by the "material-balance equation" show unusually good agreement with that principle. Estimates of oil initially in place made by the material-balance method and the sand-volume method are in good agreement at 116 to rzo million barrels. The reservoir-pressure history of the pool reflects the reaction of a reservoir to production, proration and secondary-recovery practices. The cost of the extensive program of reservoir study in the Jones sand pool has been estimated, in order to emphasize the value derived from such an investment through better understanding of a reservoir&apos;s reaction to production practices. Unit operation of 140 of the 146 Jones sand wells made possible an effective unitized gas-injection pressure-maintenance program. Res-ervoir-pressure decline was arrested, natural flow was maintained, and pumping and lease equipment were conserved. An increased ultimate recovery of zo million barrels beyond the estimated 34 million barrels primary recovery is indicated at present. Extension of the Jones sand unit to include the undeveloped Cotton Valley formation will permit additional recovery of otherwise uneconomic reserves of oil through wells no longer required in the Jones sand operations. Introduction The Schuler field comprises approximately 4000 acres in and about sec. 18, T. 18 S., R. 17 W. in west central Union County, Arkansas. Three reservoirs are procluctive of oil and gas: the Cotton Valley formation, the Jones sand, and the Reynolds oolite section of the Smackover limestone. The Jones sand pool is the most important reservoir from an engineering viewpoint. It possesses the traditional and somewhat classic characteristics usually associated with an anticlinal trap. Development and operations have followed the dictates of advanced engineering practices. The pool has attracted attention because of the unusually detailed reservoir data obtained, its interesting production history, and the success of the unitized gas-injection pres-sure-maintenance operation now being carried out. The purpose of this paper is to present a summary of the engineering data relating to the field, with particular reference to the more interesting general applications of

Jan 1, 1944

By H. H. Kaveler

A summary of the reservoir engineering and related geologic data on the Schuler field, Union County, Arkansas, is presented here in a manner intended to interest both technical and nontechnical readers. The Cotton Valley formation and the Reynolds oolite are oil-productive formations in the Schuler field, but the Jones sand pool, at a depth of 7500 ft., developed with 146 wells on zo-acre spacing, is the reservoir of principal interest. The Jones sand sandstone reservoir is an anticlinal trap typically gas-drive or depletion type in performance. The core analyses from 88 per cent of the wells drilled, together with drilling time and electric-log data, yield an accurate estimate of the "productive" sand thickness and its areal distribution over the pool. Accurate production statistics, monthly reservoir-pressure surveys, and bottom-hole sample analyses when correlated by the "material-balance equation" show unusually good agreement with that principle. Estimates of oil initially in place made by the material-balance method and the sand-volume method are in good agreement at 116 to rzo million barrels. The reservoir-pressure history of the pool reflects the reaction of a reservoir to production, proration and secondary-recovery practices. The cost of the extensive program of reservoir study in the Jones sand pool has been estimated, in order to emphasize the value derived from such an investment through better understanding of a reservoir&apos;s reaction to production practices. Unit operation of 140 of the 146 Jones sand wells made possible an effective unitized gas-injection pressure-maintenance program. Res-ervoir-pressure decline was arrested, natural flow was maintained, and pumping and lease equipment were conserved. An increased ultimate recovery of zo million barrels beyond the estimated 34 million barrels primary recovery is indicated at present. Extension of the Jones sand unit to include the undeveloped Cotton Valley formation will permit additional recovery of otherwise uneconomic reserves of oil through wells no longer required in the Jones sand operations. Introduction The Schuler field comprises approximately 4000 acres in and about sec. 18, T. 18 S., R. 17 W. in west central Union County, Arkansas. Three reservoirs are procluctive of oil and gas: the Cotton Valley formation, the Jones sand, and the Reynolds oolite section of the Smackover limestone. The Jones sand pool is the most important reservoir from an engineering viewpoint. It possesses the traditional and somewhat classic characteristics usually associated with an anticlinal trap. Development and operations have followed the dictates of advanced engineering practices. The pool has attracted attention because of the unusually detailed reservoir data obtained, its interesting production history, and the success of the unitized gas-injection pres-sure-maintenance operation now being carried out. The purpose of this paper is to present a summary of the engineering data relating to the field, with particular reference to the more interesting general applications of

Jan 1, 1944

By Herbert H. Uhlig

Although the mechanical properties of high-carbon manganese-iron alloys, particularly the Hadfield manganese steels, have been established, the literature discloses discrepancies in the reported properties for the low-carbon alloys. Hadfieldla summarized the existing data up to 1927, including the investigations of Guillet, Arnold, Strauss, Burgess and Aston, and reported his own values for alloys containing for the most part from 0.06 to 0.I5 per cent carbon. He noted: From these comparisons it wil! be seen that while there is a broad and general agreement as to the character of the alloys at the different manganese percentages, there are disparities in individual cases, especially as regards the degree of toughness or brittleness displayed by an alloy with certain percentages and with particular types of treatment. These differences are not always readily explainable.lb His data showed that alloys containing 4 to 10 per cent manganese water-quenched from Iooo°C. were brittle and hard with maximum brittleness at about 7 per cent. Slight improvement in ductility was obtained with compositions from 10 to 17 per cent manganese. Alloys containing up to 17 per cent manganese slowly cooled rather than quenched from 87o°C., he found, were slightly improved in ductility with significant improvement in alloys analyzing 4.1 and 4.8 per cent manganese. Recently Walters, Kramer and Loring2 reported mechanical properties for alloys made up from electrolytic manganese and ingot iron and containing from 0.02 to 0.04 per cent carbon. They showed that a tempering treatment at 54o°C. (Iooo°F.) for one hour significantly improved the ductility of compositions ranging from 6.7 to &apos; 20.7 per cent manganese. The differences of these compared with Hadfield&apos;s results they considered to originate in this tempering treatment plus the fact that Hadfield&apos;s alloys contained higher carbon and phosphorus (0.06 to 0.I5 per cent C; 0.06 to 0.07 per cent P compared with 0.02 to 0.04 per cent C, <o.ooI per cent P). In this paper it is shown that of the low-carbon alloys (0.02 to 0.03 per cent) containing from 3.3 to 21.5 per cent manganese moderately or rapidly quenched from IOOO°C. some are brittle or ductile, depending on presence or absence of hydrogen. Hydrogen is readily absorbed at high temperatures, and much of it is retained when the alloys are cooled to room temperature. The presence of hydrogen in the range of composition from 10 to 18 per cent manganese is a major factor in determining relative ductility. At 22 per cent manganese, and also at compositions below 10 per cent manganese, factors other than or in addition to hydrogen play a role. These are discussed. Also data are presented to show that hydrogen absorbed by the high-carbon alloys of Hadfield composition is without effect on their mechanical properties.

Jan 1, 1944

By Herbert H. Uhlig

Although the mechanical properties of high-carbon manganese-iron alloys, particularly the Hadfield manganese steels, have been established, the literature discloses discrepancies in the reported properties for the low-carbon alloys. Hadfieldla summarized the existing data up to 1927, including the investigations of Guillet, Arnold, Strauss, Burgess and Aston, and reported his own values for alloys containing for the most part from 0.06 to 0.I5 per cent carbon. He noted: From these comparisons it wil! be seen that while there is a broad and general agreement as to the character of the alloys at the different manganese percentages, there are disparities in individual cases, especially as regards the degree of toughness or brittleness displayed by an alloy with certain percentages and with particular types of treatment. These differences are not always readily explainable.lb His data showed that alloys containing 4 to 10 per cent manganese water-quenched from Iooo°C. were brittle and hard with maximum brittleness at about 7 per cent. Slight improvement in ductility was obtained with compositions from 10 to 17 per cent manganese. Alloys containing up to 17 per cent manganese slowly cooled rather than quenched from 87o°C., he found, were slightly improved in ductility with significant improvement in alloys analyzing 4.1 and 4.8 per cent manganese. Recently Walters, Kramer and Loring2 reported mechanical properties for alloys made up from electrolytic manganese and ingot iron and containing from 0.02 to 0.04 per cent carbon. They showed that a tempering treatment at 54o°C. (Iooo°F.) for one hour significantly improved the ductility of compositions ranging from 6.7 to &apos; 20.7 per cent manganese. The differences of these compared with Hadfield&apos;s results they considered to originate in this tempering treatment plus the fact that Hadfield&apos;s alloys contained higher carbon and phosphorus (0.06 to 0.I5 per cent C; 0.06 to 0.07 per cent P compared with 0.02 to 0.04 per cent C, <o.ooI per cent P). In this paper it is shown that of the low-carbon alloys (0.02 to 0.03 per cent) containing from 3.3 to 21.5 per cent manganese moderately or rapidly quenched from IOOO°C. some are brittle or ductile, depending on presence or absence of hydrogen. Hydrogen is readily absorbed at high temperatures, and much of it is retained when the alloys are cooled to room temperature. The presence of hydrogen in the range of composition from 10 to 18 per cent manganese is a major factor in determining relative ductility. At 22 per cent manganese, and also at compositions below 10 per cent manganese, factors other than or in addition to hydrogen play a role. These are discussed. Also data are presented to show that hydrogen absorbed by the high-carbon alloys of Hadfield composition is without effect on their mechanical properties.

Jan 1, 1944

By C. Ek

Tailings originating from the gravity concentration of a gold ore containing about 14 g/t Au have been treated by various beneficiation methods. These tailings have been screened on the 147 and 74 micron sieves and the two coarsest fractions have been separated on shaking tables with unsatisfactory results, but the concentrates have been examined in polished sections for mineragraphic analysis. Very simple flotation flowsheets have been applied to collect most of the gold, recovery and grade varying with the regrinding time in a ball mill. Cyanidation tests have shown that this type of treatment is also applicable to such tailings.

Jan 1, 1991

Gold was discovered in the Bendigo area of Victoria in 1851 (Willman and Wilkinson, 1993), and all the early gold mining of any note involved washing (puddling) the gold out of the regolith or alluvium. The waste material from this process was a semi-fluid mixture of rock debris, soil and water, referred to as `sludge&apos;. Puddling machines were gradually introduced to speed up the puddling process (Cole, 1994), and by 1855 an estimated 2000 machines were in the district (Anderson, 1978). In 1859 it was estimated that approximately 2 293 000 m3 of material was puddled annually by the machines on the eastern side of the goldfield, whose waste drained into Bendigo Creek and its tributary gullies. It was also estimated that after the gold was removed, approximately one-quarter of the residue/sludge consisted of the heavier, coarse-grained material which settled out fairly quickly, while the remainder, approximately 1 720 000 m3, was the fine-grained material which flowed downstream for some distance (VPP, 1859 - 60). From these figures it can be assumed that for the ten years during which this volume of puddling was maintained (1854 - 1864) over 5 700 000 m3 of gravels and sands and 17 200 000 m3 of fine-grained sludge had been discharged into and around Bendigo Creek. This was enough to cover an area of over 400 km2 to a depth of 5 cm. By 1859 the problems associated with the sheer volume of sludge being discharged were such that a Royal Commission was appointed to `Enquire into the Best Method of Removing the Sludge from the Gold Fields&apos; (VPP, 1859 - 60). The goldfields referred to were those in the Bendigo area around the township of Sandhurst (now known as Bendigo). The Report of the Commission (VPP, 1859 - 60) stated that: `... inspection of the country bordering upon the course of the Bendigo Creek, to a distance of about fifty miles from Sandhurst . . . &apos; had revealed that the sludge had &apos; . . . filled up watercourses and flooded pasture lands . . . &apos;. It also noted that &apos; . . . even on the plains, thirty or forty miles away from Sandhurst, where the sludge flows thin, and is relieved from its heavier particles, we found it baked into a perfect concrete, and in thicknesses varying up to two feet or more . . . &apos;. The italics were used for emphasis in the original text. As it was considered unlikely that the physical evidence for such widespread inundation would have disappeared completely over the intervening 130 or so years, a project was initiated to locate any evidence of the inundation in the current landscape. If such evidence were to be found, then an estimate could be made of both its extent and its effects on the topography, drainage, and land-use of the inundated area. Extensive field work has determined that over 700 km2 to the north of Bendigo was inundated by the sludge. The area has not been uniformly covered, but has occasional `inliers&apos; which have obviously escaped inundation by being slightly higher than the surrounding areas. Today the sludge is readily identified as a very fine-grained, hard-setting, concrete-like `capping&apos; overlying a well-developed, well-structured, pedal horizon, or in some instances, the gravels and sands of a creek bed. The thickness of the sludge capping varies between a few centimetres and three metres (Peterson, 1996). The buried topography was gently undulating, in direct contrast with the almost unnatural flatness of

Jan 1, 1997

By Huaiyu Liu, Shan Liu, Dashang Chang, Maixi Lu, Yaqun He, Yali Kuang

The expert system for coal preparation plant design mainly solves the crux--separation flowsheet design and optimization of product structure. There are twelve basic flowsheets available in the system which are representative of financial plants. The system can select better flowsheets automatically according to the property of feed and scale of plant. Then, it can choose the best flowsheet and product model from the better flowsheets through analysis and optimum calculation. The expert system is made up in Turbo Pascal 6.0 and consists of three sub-systems: Lump and grain coal system, coal slimes processing system, and raw coal system. Several representation methods, such as production rule, procedure, and object-oriented programming, are used to express the expert&apos;s knowledge in the system. To decide the optimum product structure, Zangwill&apos;s method is used to make an advance product model. The expert system has the performance of interpretation strategy, by &apos;tracer" technology and pre-arrangement text, and of learning new expert&apos;s knowledge.

Jan 1, 1996

By Alexander Malahoff

The study of why and how life survives in the Extreme environment is a major frontier of science today. Extremophiles are organisms that require extreme environment including high temperature, pH, pressure and salt concentration, or low temperature, pH, nutrient concentration, or water availability. Their common habitats are geothermal vents, pools, lakes and craters of active volcanic regions, such as those of New Zealand, Japan, Kamchatka, Yellowstone USA or the hydrothermal vents of the ocean ridges and submarine volcanoes. These settings are accessible by foot, boat, helicopter, or submersibles. This presentation examines the geology, chemistry of geothermal sites of New Zealand, including the active volcano, White Island, Yellowstone, the submarine volcano Loihi in Hawaii, and sections of the mid-ocean ridges. Designing process and construction of Extremophilic sampling and bioreactor systems used in the study of Extremophiles will be discussed. The driving force behind the research of extremophiles is not only the fundamental science, but also biotechnological potential associated with these microorganisms and their cellular products. The University of Hawaii?s Marine Bioproducts and Engineering Center (MarBEC) is laying the foundations for such new industries.

Jan 1, 2001

By Edward B. Dismukes, Walter R. Dickson

Measurements of current efficiency at an iron anode during the electrolysis of FeO-CaO-SiO2 melts contained in an iron crucible indicate that compositions of high SiO5 content conduct current almost entirely by ionic mechanisms. Hozueuer, compositions of high metal oxide content give euidence for considerable nonionic conduction that can be attributed to p-type semicon-duction. Measurements of transference numbers in a Hittorf-type cell show that both calcium and iron ions are important contributors to ionic conduction. ELECTROCHEMICAL properties such as conductance, transference numbers. and oxidation or reduction at an electrode have been studied as means of delineating the structure of simple silicate melts that are related to the more complex slags encountered ir steelmaking processes.&apos; Measurement of these properties has strengthened the concept that molten silicates are constituted of metal ions and of silicate networks. Typically, the magnitude of electrical conductivity and the extent of agreement with Faraday&apos;s law have given evidence for ionic structures, and transference numbers have shown cations to be the exclusive carriers of electrical charge. However, melts containing oxides of iron, FeO in particular, have been found to exhibit nonionic conduction of curx,ent. The work by Inouye, Tomlinson, and chipman&apos; demonstrated semiconduction, presumably of the p-type, in molten wüstite. Simnad, Derge, and George3 and Dukelow and Derge,4 in studying the electrolysis of FeO-SiO2 and FeO-MnO-SiO2 melts, concluded that p-type semi-conduction occurs in these systems, although ionic conduction is generally favored by increased percentages of MnO or SIO2. Previous research on the electrochemistry of

Jan 1, 1962

By Steven G. Vick

Not too long ago a mill superintendent, when asked where his tailings were being disposed, could simply shrug his shoulders and point to the open end of the thickener discharge pipe. This “out of sight, out of mind” approach to tailings disposal is a practice of the past. Today there are very few planned hardrock or energy-related mining facilities where tailings disposal has not been identified as the major area of impact and controversy. In fact, development of some ore bodies has been stymied altogether by lack of suitable sites or methods for tailings disposal. The bottom- Iine result is that tailings disposal often controls the permitting lead time and has a significant influence on construction cost (up to 2070 in some cases) of new minemill complexes. The following article, the first in a series of three, explores technical background and historical perspectives on siting and design of tailings impoundment facilities.

Jan 6, 1981

By Lee G, Stitt P

The term "industrial minerals" covers a vary wide field. However in Australia this field tends to be characterised by the follow- ing: (1) Relatively low unit values. (2) Product specifications can be exacting compared to the metalliferous field. (3) Product specifications often have to be tailored to the needs of the end user. (4) Beneficiation plants tend to involve low capital outlays relative to the metalliferous field. However they often have to produce products&apos;to a range of specifications. (5) Technology often influences what can be considered as reserves. (6) Because of low unit values industrial minerals tend to be relatively cost sensitive. This is particularly the case in regard to transport. (7) Location of deposits near to major urban areas (markets) dictates a greater pressure on ecological aspects. (8) In Australia there has been a tendency to vertical integration largely due to the restricted market available. Reserves assessment is shown to be critically dependent upon the above Factors.

Jan 1, 1979

By P O. Andersson

Mining of sill pillars is more difficult than the ordinary mining. The sill pillar mining is performed under more difficult conditions and the mining of the sill pillar itself produces more problems; failure of the rock due to high stresses, difficulties in controlling the fill above, overall stability of the stope and special requirements on the technique for backfilling. Altogether this makes sill pillar mining technically difficult and often not profitable. A project was therefore initiated with the aim to increase the mineable ore reserve by making sill pillars mineable, both technically and economically. The project aimed at developing technique for already existing sill pillars as well as planned sill pillars. For the existing sill pillars a technique would have to be developed for mining beneath unstabilised fill. For sill pillars that would be created in the future, the most suitable mining method and methods of supporting or stabilising the fill in the stope above was to be chosen within the project.

Jan 1, 1998

Develop a machine which can accurately simulate both the breathing and metabolic functions of a human being. The advantages of such a machine over a human being for testing of respiratory protective devices lie in its ability to quantify metabolic input, its repeatability, and the lack of a need to deal with the vagaries of human subjects. Breathing simulation has been widely achieved throughout the world but metabolic simulation has not. Approach Utilize the latest computer technology and place the complex portion of the system in software, leaving the mechanical portion as simple as possible. How It Works The concept for the automated breathing and metabolic simulator (ABMS) was developed through a research contract with the Pennsylvania State University. The ABMS utilizes a continuous removal/replacement concept to simulate metabolic functions, with breathing and metabolic functions being controlled by a computer. The mechanical portion of the machine is simple; the complexity of the system lies in its computer software which is not subject to maintenance problems.

Jan 1, 1987

By Eric Hedburg

This paper was originally prepared as a picture of the situation presented by the mining industry referred to at the end of the year 1899; and some of the descriptions and drawings of special mines, etc., may not completely show their condition a year later. The statements made as to the cost of mining and concentration, however, still hold good. As to other general statements made in the paper, it is believed that the following additional facts cover all that is required to complete them for the additional year. The condition of the mining industry in the Joplin district was better at the close of 1900 than at any time during several preceding years. Values seemed to have adjusted themselves, in considerable degree, to the commercial and technical circumstances, the cost of mining-supplies of all kinds had returned to a normal basis, and the product of ore found a ready sale,

Jan 1, 1902

By Thompson IR, Solomons SS

Underground mining with the cut and fill method has been declining during the past decade or so, being replaced mostly by sublevel open stoping methods. During 1983 the Australian Mineral Industries Research Association Ltd. (AMIRA) commissioned a review of the method, with the aim of compiling the state-of-the-art, indicating future trends and recommending topics for research that would be needed to support this future mining. Mines using the cut and fill method in Australia and three other countries were visited to compile current practices and expected developments.Cut and fill is mostly used where geological and ground conditions are unsuitable for open or caving methods. These range from narrow, irregular orebodies to wide, massive orebodies where pillars are retained in ore. There is significant potential for improvement and further development of the method. It may then be used in a broader range of conditions and for orebodies that may not otherwise be viable to mine.

Jan 1, 1985

By W. M. Myers

[The principle of the application of electrolytes for deflocculation of fine materials in order that impurities may settle out, and the subsequent flocculation of the suspended particles by a different reagent, is well known and has been applied successfully to clays. Flocculation is also applied with success to ore slimes. Thus certain electrolytes, particularly alkalies added to a suspension of colloidal particles cause deflocculation so that, suspension may be-maintained indefinitely. The addition of bother electrolytes particularly acids, on the contrary produce&apos;s flocculation and the articles produce&apos;s are rapidly precipitated from suspension leaving a clear liquid above: the precipitated mass. Salts of trivalent elements such as aluminum act similarly. Due to its cheapness the double sulphate of aluminum and potassium, ordinary alum, has been used extensively for treating clays. These properties of electrolytes. and. their utilization in the commercial: preparation of clays have been described in publications of the Bureau of Mines.2]

Jan 1, 1927

By Paul A. Bailly

Geology is not the problem. Because of inflation, taxation, and politics more reserves are being reconverted to uneconomic resources than there are new reserves created by exploration and extraction technology.

Jan 1, 1976

Close spatial relationships between the deposits of the Etheridge Goldfield (23,000 kg of bullion) and various regional geological and geophysical features suggest that genesis of the ore deposits was a multi-stage process that started with magmatic and metamorphic stages in the mid-Proterozoic, climaxed with structural and hydrothermal stages in the late Palaeozoic and terminated with an oxidation enrichment stage in the Cainozoic. Acceptance of this hypothesis permits classification of the Georgetown region into areas likely to contain deposits of the Etheridge type and those unlikely to do so. Consequently there is little scop- for the discovery of extensions of this field. However, the stratigraphic interval between the source rocks of the Etheridge field and stratigraphically higher host rocks of the Croydon field may contain disseminated replacement gold deposits of the Carlin type. The potential host (pyritic carbonaceous, and locally dolomitic siltstone of the Candlow Formation) is locally faulted and cut by granitoids and the extension of a mineralised, long-standing zone of structural weakness.

Jan 1, 1980