Search Documents

By DR. DOUGLAS

Discussion of the Paper of Dr. Douglas, presented at the Toronto Meeting of the Institute, July, 1907 (Trans., xxxviii., 455 to 471). EDGAR HALL, Silverspur, Queensland, Australia (communication to the Secretary*) :-Dr. Douglas has written on this subject before, and his influence has had a powerful effect on the side of freedom among the younger generation of engineers. Moreover, it is not the first time that he has attributed the decline of the copper-smelting industry in Swansea to the secrecy maintained by the firms there engaged in smelting-operations. In this latter statement I think his conclusions are open to criticism. Whether the firms referred to have suffered by their secrecy is their own business-I. bold no brief for them ; but that the decline of the copper-industry at Swansea was inevitable seems to me to be proved conclusively by Dr. Douglas's own writings. In his paper on The Copper Situation,1 Dr. Douglas says "In comparing iron and copper mining, . . . it must be remembered that 2 tons of average iron ore from the most prolific source now available will make 1 ton of metal; whereas from 33 to 75 tons (say an average of 50 tons) of copper ore must be mined to produce 1 ton of copper." And further: "Last year's production of iron was made from approximately 50,000,000 tons of ore. Our copper mines, to yield a production of 900,000,000 pounds, must have handled approximately 22,000,000 tons of ore, or nearly half the quantity raised from our iron mines." Is not this the key to the whole situation ? In transporting the 50,000,000 tons of iron-ore, 25,000,000 tons of the metal iron were carried so much nearer to the market, but the transportation of 22,000,000 tons of copper-ore would have carried only 450,000 tons of the metal copper nearer to its ultimate destination. The small percentage of copper available in its ores makes

Sep 1, 1908

By R. L. Grayson, L. L. Probert

"A three-year project focusing on the depth profiling of respirable coal mine dust particles using scanning electron microscopy coupled with energy dispersive X-ray analysis resulted in the development of statistically classified particle-behavior models. The models depict the changing silicon fraction for particles at 5-, 7-, 9-, and 11-keV accelerating voltages, thereby giving a clear indication of the nature of various types of mineral particles. This paper focuses on the results for respirable quartz particles sampled from five underground coal mines across the US. Through statistical analysis of results the relationship between the fraction of surface available quartz in respirable dust samples and coal rank is established for three Pennsylvania coal seams. IntroductionThis is the last in a series of papers detailing the results of SEM/EDX-based analyses of respirable coal mine dust particles collected from field sampling. Previous papers have detailed preliminary results and the statistical validity of the methodology (Grayson, Andre, and Simonyi, 1990; Grayson, 1991). This paper presents the final results of the analysis of respirable dusts from five coal seams with a range of coal rank:• Lykens Valley seam (anthracite), eastern Pennsylvania• Brookville (A) seam (mid-vol bituminous), central Pennsylvania• Pittsburgh seam (high-vol B bituminous), western Pennsylvania• No. 6 seam (high-vol C bituminous), Illinois• Wadge seam (sub-bituminous A), ColoradoSEM/EDX-based techniques were applied to try to clarify the role of quartz as an etiologic agent in coal workers' pneumoconiosis (CWP). It was hypothesized that previous studies were hampered by the restrictions of bulk analysis techniques and that particle-level analyses were needed to answer a number of questions concerning the role of quartz in CWP and its progression.Since 1985, a large number of the respirable dust samples submitted to MSHA are analyzed for free silica (Tomb, Parobeck, and Gero, 1986). Our reasearch shows that conventional bulk analysis techniques may not give a true indication of the biologically available, or active, quartz in mine dusts. Analytical evidence indicates that respirable dust samples may contain many quartz particles that are occluded, or coated, resulting in a bulk analysis for ""free silica"" that may not be indicative of the biologically available quartz surface."

Dec 1, 1996

By M. J. Brevoort

Research work in the Bureau of Mines cryogenic laboratory requires the use of high-sensitivity galvanometers of the d'Arsonval type in a building that is subject to unusually severe vibrations. A modified form of the galvanometer suspension described by Julius3 has damped the vibrations so successfully that a short note concerning it is thought to be desirable, The laboratory is on the site of the Amarillo helium plant near a building that houses gas engines of from 180 to 250 hp., driving compressors and electric generators. The distances from the galvanometers to the individual engines range from about 80 to 180 feet. The subsoil, consisting of black clay loam, transmits the impulses without much damping. The usual methods of protecting galvanometers from vibration were tried and proved fruitless. A Julius suspension purchased on the market was carefully installed in the hope that it would overcome the difficulty, but the conditions were too severe even for this elaborate arrangement. Several mudifications of the original Julius suspension, which were then introduced, resulted in almost complete elimination of all vibrational effects.

Jan 1, 1931

By M. Clair Smith

The Sweetwater, Castro, Trinidad, New London, and Hilltop chromite properties are situated within an area 8 miles long and 1 mile wide between San Luis Obispo city and Morro Creek, San Luis Obiso County, Calif. Development work at this group of mines was a part of a long-range project by the Bureau of Mines to develop strategic mineral reserves in the United States in accordance with the Strategic Minerals Act of 1939. The junior author of this report participated in the preliminary examinations made in 1941 of the chromite deposits that later in the same year were the subject of more intensive investigation under the immediate supervision of the senior author. The ore occurs in lenses and kidneys in masses of dunite contained in large poridetite areas. Production has boon in the form of lump ore and concentrates from disseminated ore. Work by the Bureau of Miner included surveying, mapping, trenching, sampling, and assaying. It is summarized separately in the text under the name of each mine investigated. The report gives a brief history of the district, describer the concentrating plant of the Castro Associates, and gives detailed results on sampling and assays at the various proportion.

Jan 1, 1951

By L. Tong

Stirred milling of laterites offers possibilities for improving liberation and selective size reduction of soft nickel-bearing minerals in laterites. Batch grinding tests were performed in a Netzsch LME4 stirred mill on a siliceous goethitic (SG) nickel laterite sample (-2000 µm particle size) to evaluate the effect of operating conditions such as stirrer speed, grinding time, pH, solid content, water salinity and charge volume. The target was to produce a -38 µm fraction in the milling product with high nickel recovery and grade. Addition of dispersant (sodium hexametaphosphate) was also optimized with respect to the rheology of the slurry. In terms of stress intensity, the optimum grinding conditions for selective size reduction were: 1000 rpm, 50 per cent charge volume. At higher stress intensity (2000 rpm), Ni recovery in the -38 µm product was higher, but Ni grade was low, due to the breakage of the harder siliceous particles. Decreasing the yield stress by modifying slurry pH or adding dispersant improved the rheological properties of the pulp, but had no great influence on Ni upgrade in the fine product. Modifying water salinity by adding 2 M NaCl had also little effect. The breakage of the +38 µm particles in the feed determined Ni upgrade greatly. Ni grade in the -38 µm product decreased with grinding time, suggesting that the Ni-bearing minerals break first, while the harder siliceous minerals have a lower breakage rate. The breakage rates with respect to sample mass for Ni, Mg and Si indicate that: Mg > Ni > Mass > Si. The optimum grinding time for the highest Ni upgrade was 0.25 min. The Ni grade increased from 0.88 per cent to 1.35 per cent (upgrade 54 per cent), with 24 per cent Ni recovery. Keywords: fine grinding, stirred media mill, nickel laterite, slurry rheology

Sep 1, 2012

By A. Danaei, A. McLean, M. Barati, C. Ravindran

"The aluminum industry generates about 90 million tonnes of red mud each year. Previous research shows it could be utilized as a refining flux with a high capacity to absorb phosphorus and sulphur from hot metal in the steel industry. The present study was undertaken to evaluate the melting properties of such fluxes, as it affects the effectiveness of the flux. The results show that the melting behavior of red mud is strongly affected by lime addition and the characteristic melting/softening temperatures reach minimum VALUES (at 32.7 wt% CaO. From these findings, a correlation was established between melting behavior and optical basicity. This allows one to adjust the composition of the flux based on the process requirements. INTRODUCTIONThe aluminum industry generates about 90 million tonnes of bauxite residues each year. This residue is usually red in color because it contains a substantial amount of iron oxide. The red mud, as it is called, is a solid waste with a high concentration of sodium oxide, high pH (10 to 13), and high alkalinity, and thus is harmful to many forms of life. Traditionally, the material is stored in large tailings ponds within the plant’s vicinity (Power, Grafe, & Klauber, 2009). Development of solutions for safe disposal or preferably using this residue for other industrial processes or applications could help restore polluted locations and eliminate a negative impact on the environment (Haake, 1988; Power et al., 2009; Yan & Xuegong, 2010).The mineralogy and chemical composition of red mud depends on the quality of the bauxite and refining process parameters. In general, it consists of iron oxide (Fe2O3), aluminum oxide (Al2O3), titanium oxide (TiO2), sodium oxide (Na2O), silicon oxide (SiO2), and calcium oxide (CaO) (Power et al., 2009). Like most ores and soils, bauxite can contain trace quantities of metals such as arsenic, beryllium, cadmium, chromium, lead, manganese, mercury, nickel, and naturally-occurring radioactive materials, such as thorium and uranium. Most of these trace elements stay in the residue (Power et al., 2009)."

Jan 1, 2012

By Reza Kamali, Mohsen Bashiri, Hadi Fanisalek

"Nomenclature: A: area (m2), C: heat capacity (WIK), cp: specific heat (J/Kg K), d: internal tube diameter (in), F: correction factor for multi-pass and crossflow heat exchanger, h: convective heat transfer coefficient (W/m2K), k: thermal conductivity (W/mK), L: length (m), m: mass flow rate (Kg/s), W: flow rate, N: number, Q: heat rate (W), R: thermal resistance, T: temperature (°C), U: overall heat transfer coefficient (W/m2K), ;1,,P: pressure drop (Pa), ;1,,T: temperature difference (°C), p: density (lb/ft3), N: number of tube passes, U,: velocity in tubes, iJh: head loss in feet of flowing fluid, Up: velocity in the pipe leading to and from the heat exchanger (ft/sec), µ: viscosity ( cp ), Llpf frictional pressure loss (psi/l 00 equivalent ft of pipe) Subscripts: b: baffle, c: cold, cf counter flow, ex: exchanger, f: fouling, h: hot, i: inlet-inner, ib: inlet baffle, lm: logarithmic mean, m: mean, o: outlet-outer, s: shell, t: tube, w: wall AbstractThe main bottleneck for primary aluminum production industry is dealing with a huge amount of input energy. The fact is that part of provided energy to aluminum production smelters will be lost as waste heat and it never used for aluminum production. One part of waste heat is escaping from the potroom exhaust gases, which was studied for possible recovery in a desalination plant to produce distilled water and the paper was presented in 2011 TMS Annual Meeting. However, it was shown that waste heat recovery plant to produce distilled water is highly profitable but the main fact is that the exhaust gases from potroom are highly corrosive, abrasive and dusty. The main challenge for desalination plant construction, which is using aluminum smelter exhaust gases as the main heat source, is the highly corrosive environment that makes the situation difficult and complicated for equipments design and plant construction. In this paper, we are trying to study a detailed investigation regarding the heat exchangers fouling, corrosion in heat exchangers including heat exchangers' material, how often we need to shut down the plant for maintenance or cleaning, and plant thermal efficiency with considering fouling."

Jan 1, 2012

By Russell R. Trengove

In order to extend or delimit the known ore reserves adjacent to the Comet Coalition property on the western slope of the Highland Peak Range about 8 airline miles west of Pioche, Nev., the Bureau of Mines undertook an exploration project of diamond drilling. Production figures from this property, formerly known as the Schodde, are not available, but it has been reported that small amounts of rich silver and gold ore were Shipped by wagon to a smelter in the Salt Lake valley during 1900-1910. Small shipments were reported for the period 1915-1927, also. A study of the Pioche District by the Federal Geological Survey in 1942 and 1943 was the basis for the exploration program of the Bureau of Mines in 1947 This program consisted of diamond-drilling three holes. The total footage was 2,967 feet. No. 1 hole was drilled 1,260 feet, a record depth for diamond drilling in the Pioche District. Silver-bearing lead-zinc sulfide ores are found in the Combined Metals limestone, known locally as the C.M. bed, These deposits have been formed by replacement of the limestone that is inclosed in the Pioche shale.

Jan 1, 1949

By Mike Johnson, Greg Andrews, Niels Verbaan, Ernesto Bourricaudy, David Dreisinger

Search Minerals has developed a Direct Extraction Process for recovery of rare earths from the Foxtrot and Deep Fox deposits in Labrador Canada. The process includes crushing, acid treatment, water leaching, impurity removal, precipitation of an intermediate rare earth product and finally re fining of the intermediate product to produce a high purity mixed rare earth oxide (*99% total rare each oxides). The Direct Extraction Process has been validated in an extensive demonstration pilot plant program at SGS Minerals. A total of 3 tonnes of material was processed to produce final mixed rare earth product. The results of the demonstration pilot plant program are reported.

Mar 1, 2018

By K M. P Singh, K M. K Sinha, G S. Jha, T Gouricharan, K K. Sharma

The majority of the powerplants in India are fed with non-coking coals, with the coals dispatched from their respective mines via wagons loaded by a rapid loading system or pay loader. The usual top size of coal is 200 mm and sampling is carried out manually from wagons. The manual method of wagon top sampling of large size raw coal is not only difficult, but also violates some of the fundamental principles of sampling. As per sampling requirements, samples are to be drawn from the full depth of the wagons, which is impossible to be done manually. Since the ash distribution in the different size fractions is not homogeneous, the results from the samples, which do not reflect the true size distribution of the lot, are likely to be biased. More importantly, sample collection by shovel from the top is a function of human discretion and not governed by the equiprobability rule. In another case, the sample has been collected by a cross belt-type auto mechanical sampler for 200 mm size coal at one of the super thermal power stations. Test analysis shows that coal collected using a cross belt-type mechanical sampler also has significant deviations from stopped belt coal samples of 200 mm size due to size segregation. Studies carried out on wagon top sampling through specially designed experiments reveal some interesting features. The presence of bias in wagon top sampling is apparent when compared with the ‘stopped belt’ sample. In this paper, a comparative study between manual wagon top sampling/auto mechanical sampling with respect to stopped belt sampling has been conducted for coal of size 200 mm. In addition, precision studies have been performed for wagon top sampling/mechanical sampling for Indian thermal powerplants.CITATION:Sinha, K M K, Sharma, K K, Jha, G S, Singh, K M P and Gouricharan, T, 2014. A comparative study of manual wagon top sampling and auto mechanical sampling of 200 mm size coal with respect to stopped belt sampling of thermal coal at Indian super thermal powerplants, in Proceedings Sampling 2014 , pp 43–48 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Jul 29, 2014

By Run Huang, Xuewei Lv, Lei Lei, Guibao Qiu, Chenguang Bai

"The TiO2-rich slag and pig iron can be produced from ilmenite concentrate by the electric furnace process. In this study, ilmenite concentrate was reduced in a vertical furnace equipped with a weighting data acquisition system. The effects of reducing agent (carbon) amount on the iron reduction were studied. The phase transformation, morphology and chemical compositions of reduced samples were investigated by X-ray diffractometry (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), respectively. It was found that the reductive degree of ilmenite concentrate increased with the increase of reducing time. The phases of reduced samples were mostly iron, rutile, Ti3O5 and Fe2TiO5. The mass loss percentage increased with increasing the carbon amount from 8% to 12%. When the carbon amount exceeded 12%, the mass loss percentage decreased with the increasing of carbon amount.IntroductionIlmenite and rutile are the main raw materials for producing titania pigment and titanium metal. With the development of the titanium industry, huge amounts of titanium resources are needed. As sources of high-grade titania mineral decrease worldwide, more attention should be paid to the processes involving low grade mineral such as ilmenite ore. In ilmenite, MgO and CaO are the gangue parts. Therefore, the ilmenite refining becomes more and more popular. In the previous studies, the methods of ilmenite refining are electric furnace smelting, direct acid leaching, selective chlorination and thermal reduction [1]. Electric furnace smelting method is widely used in the titanium industry, however, which consumes a great deal of energies and has a high CO2 emission. Its essence is to remove iron oxides and obtain a high titania slag. So the thermal reduction of ilmenite concentrate is an important step in titanium industry, which can decrease carbon reagent consumption and save energy.Over the past several decades, many studies have been carried out on the mechanism and kinetics of the reduction of different ilmenite ores, which are as follows: The carbothermal reduction of Panzhihua ilmenite initiated at about 860 oC. In the temperatures ranging from 900 oC to 1400 oC, the reaction rate was changed like a shape of “M”. That was to say that the reaction rate increased with the growth of temperature at first, then decreased, afterward increased again and at last the reaction was arrested [2]. The Mohammad A.R group [3, 4] showed that the carbothermal reduction of primary ilmenite concentrate was faster in hydrogen and initiated at a lower reduced temperature than in argon and helium. The reduction in argon and helium had about the same rate and extent. Titanium oxycarbide started at 1000°C in hydrogen. The conversion of primary ilmenite concentrate to metallic iron and titanium oxycarbide at 1200 °C was completed in 300 minutes. Monoxide as the reductant to reduce ilmenite had been studied intensively by a few research groups [5, 6]. The rate and the degree of reduction depended on the formation of a metallic shell of iron which inhibited the transfer of CO to the reaction zones; titanium had a strong effect on the mechanism and rate of reduction of iron oxides. Wang and Yuan [7] studied the reductive kinetics of the reaction between a natural ilmenite and carbon. At temperature below 1100°C, chemical reaction was the rate controlling step, at 1100 to 1250°C mixed controlling was rate controlling step, above 1250°C diffusion through the product layer controlled the reaction. Zhang [8] investigated the reduction of natural, sintered and preoxidized ilmenite concentrates in hydrogen methane mixtures. Preoxidation and sintering of ilmenite concentrates changed their phase composition and caused a sharp decrease in specific surface area of raw materials and an increase in carburization temperature. Sintering also increased the metallization temperature of iron."

Jan 1, 2011

By Xie Longshui

INTRODUCTION The gold production is from the state-owned gold mines, the local gold mines and the by-product of metal mines. Since 1975, the small gold mines have developed in rapid strides. Currently, there are about 3000 small gold mines in China. Most of them are operated by the local, and the production is about 50% of China's gold output. In the small gold mines, the normalized mining equipments are employed at most of mines, but some mines still use such backward tunnelling and mining tools as pick, shovel and hand hammer etc.. The mining techniques have developed from the primitive to the advanced, especially the methods of open stope, shrinkage and filling have been widely used. Such new mining techniques as bolting, vibrating draw, non-electric ignition and diamond drilling etc. are also introduced in the wall gold mines. In recent years, the development of small gold mines is very fast under the guidance of new mining policy which is ' rapid and great development of large-sized mines, helping small mines to develop, and quick mining for the existing mines; and encouraging the collective and the individual to operate a mine.' GEOLOGICAL FEATURES The gold veins are dominant, which are divided into two types, ie. the mesothermal deposit with altered rock in a crushed zone and the hypothermal deposit with quartz veins. The orebody distribution is not centralized, and the size of deposit and single minable orebody is small respectively. Most of deposit dip at 30° to 50°, characterized by expansion and shrinkage, ramification and compound, thinning out and reappearance, separation and composite at the parallel veins etc.. The ore grade is variable, and the factor of grade change is above 100%. The waste zones with lean or submarginal ore usually exist in deposits. As for the gold deposits with altered rock, the ore boundary is indistinct. Most of gold deposits, particularly the gold deposits with altered rock, are intruded by the late structural rock, thus the faults and joints are developed, and the rock and ore are crushed, especially the host rock of roof wall is very crushed. It ie obvious that the conditions of both formation of deposit and mining are considerably complicated. HISTORY With a long mining history and rich experiences, the local gold sectors are small, but they play an important role in China's gold mining industry. Dated from Xia and Shang Dynasty, the gold goods was made. In the Tang Dynasty, the development of gold mining industry was very fast. A Chinese poem , written by Liu Yuxi -- one of famous poets in the Tang Dynasty, says: As sun is shining over Dengzhou land, The fog on river slowly goes away, The panning girls together meet at bay, The beauty's jewels and stamps of king are gold from river sand. This poem shows the local gold mining was flourishing at that time. In 1888, the local gold mining sectors were all the rage at the moment, and the annual output of gold was as high as 21.5 tons. Since the founding of New China, the development of local gold mining was subjected to several back- sets, but certain advances are made on the whole, especially since 1970. Round about 1970,the simple, backward and indigenous mining was dominant in the small gold mines; for instance, the hand-hammer drilling, the hand-operated winch hoisting and the hand haulage etc.were main methods of gold mining . Up until the late 1970s,great changes took place in stoping, haulage and so on. Currently, some advanced technology and large-sized equipments are adopted in the local gold mines. Generally, the local small gold mining sectors play an important role in development of China's gold mining industry, and are important and attractive sectors. PRESENT DEVELOPMENT

Jan 1, 1987

By K. L. Paciorek

The primary objective of this program was to determine the toxic fume and fire hazard of materials used in the construction of mine stoppings and in the sealing and reinforcing of mine ribs and roofs. The materials investigated were: silicone, phenolic, and isocyanate-based rigid foams, as well as epoxy and acrylate mine sealants. Of the rigid foams tested, the X-156 urethane foam presented the greatest toxic hazard based on toxic load values hydrogen chloride was the main toxic species evolved by this foam. In 'lone of the isocyanate-based compositions was hydrogen cyanide the major component, but its contribution increased with temperature. The FS-24 urethane and Celotex Max-Seal isocyanurate foams had the lowest toxic load values, although these two foams have different applications for in-mine use. Of the two mine sealants tested, the latex /acrylic coating presented the greater toxic hazard with acetic acid being the main toxic species evolved.

Jan 1, 1983

By A. C. Johnstone

The aim of the study is to determine if pit lakes are a sustainable coal mine closure option in South African. The water balance, chemistry, limnology, and bacterial population of three selected pit lakes were investigated. The lakes are in the three major coal basins of South Africa and are associated with different lithologies and mining methods. The major factors driving the water balance of the pit lakes are direct rainfall, runoff, inflow from old mine workings, and groundwater infiltration, with the major losses being evaporation or discharge onto surface. The study indicated that pit lakes can be designed as ’terminal sinks’ to provide a sustainable mine closure option. The pit lakes sampled have an alkaline pH, and mostly a sodium/calcium sulphate water with total dissolved solids content of less than 3000 mg/l. The phytoplankton and microbiological data indicates that the pit lakes support aquatic life. The study shows that correctly designed pit lakes can be an environmentally sustainable closure option for South Africa’s coal mines. A suggested design manual has been developed to assist mine owners and regulators in developing sustainable coal mine pit lakes as a closure option.

Oct 1, 2021

By G. Kolosay, J. Rajala, G. Deschênes, A. Romanov

ABSTRACT: The Kupol project, located in Far East Russia, treats a high-grade, free-milling ore containing 25.5 g/t Au, 298.3 g/t Ag, and 0.5% pyrite,with a P70of 53 microns. Most of the gold occurs as elec-trum and the silver is predominantly present in the forms of acanthite, stephanite, pyrargyrite, andproustite. The mill reached the design throughput of 3,000 tpd six months after start-up. AKnelson con-centratorrecovers10.4% gold and 0.5% silver. Leaching (14.5 hours pre-treatment and 116 hours cyanidation)of gravity tailings is performed with the CANMET Enhanced Leach Process (CELP),using only 490 ppm NaCN (cyanide consumption of 1.1 kg/t). The precious metals are recovered by counter-current decantation and the Merrill-Crowe process. Calcium hypochlorite destroyscyanide and thiocyanate. Overall, gold and silver recoveries for 2008 were 95.4% and 85.6%,respectively (2.8% and7.5% higher than targets). In the first eight months of 2009, gold and silver recoveries were 95.0% and82.6%, respectively. By August 2009, the mill processed 1.42 million tons of ore with production of 1.1 million ounces of gold and 11.3 million ounces of silver. CELP performance was not affected by changes in feed grade and ore mineralogy. Additional modifications to the leaching strategy allowed further reduction in cyanide consumption and effluent treatment costs.

Jan 1, 2011

By A. L. Engel

In the period of 1942-1945, medium-grade, oxidized, lead-silver ore was mined and shipped from the Diamond district near Eureka, Nev. An encouraging tonnage of low-grade ore was developed during these operations and partly blocked-out for future mining. If the low-grade ore could be treated profitably, further development of the district would result, and production of an important strategic metal might be increased. A representative sample of Diamond district ore was obtained through the Reno office of the Mining Division for the studies described in this report. The sample consisted of lumps and fines of a highly altered siliceous rock containing much earthy red hematite and some granular black hematite. Examination with the binocular microscope showed the lead carbonate mineral, cerussite, in seams and disseminated in the hematite. No zinc or silver minerals were identified, and no sulfide minerals were present. Analyses of the ore showed:

Jan 1, 1951

By Edwin S. Johanson, Ronald H. Wolk, Clarence A. Johnson, Harold H. Stotler, Katherine C. Hellwig

The H-Coal process, an ebullated bed reactor system for converting coal to liquid fuel, is described. Results from long-duration continuous flow bench-scale operations with Wyoming Wyodak, Arizona Black Mesa, and Utah Kaiparowits Plateau coals are presented. Economic data on the conversion of these coals to liquid products are given. The potentials of the H-Coal process in regard to coal from western producers is stressed.

Jan 1, 1974

In the present work, the effect of pH, non-ionic polyacrylamide flocculant and anionic polyphosphate on rheology and settling behaviour of colloidal TiO2 suspensions (15 ? 50 wt% solid) is investigated. Maximum particle aggregation, reflecting in the highest suspension settling rate and maximum shear yield stress was achieved at pH 7.2, the isoelectric point (iep), consistent with DLVO expectation. However, the maximum aggregation condition at the iep also resulted in the poorest suspension consolidation behaviour. Significantly enhanced consolidation was achieved for a more dispersed suspension at pH values away from the iep but at reduced settling rate. Thus, when pH alone is used to control conditions which facilitate strong interparticle attraction, a high settling behaviour which is not conducive to compact consolidation results. Improved suspension consolidation may be achieved at the iep via anionic polyphosphate addition which leads to attenuation of the strongly attractive van der Waals forces and emergence of "soft" repulsion due to weak inter-particle electro-steric forces. The weak repulsion act to lubricate particles involved in the hydrodynamic interactions which controls the compressibility of the sediment bed, allowing a compact consolidation of solids to be obtained. Alternatively, non-ionic polyacrylamide homo-polymer (Magnafloc 333) was fairly effective in flocculating titanium dioxide suspensions leading to high settling rate and acceptable pulp consolidation at the iep.

Jan 1, 2006

By Martin Junker

This Notwithstanding all the debates on climate change and renewable energy, coal remains the world's no.1 primary energy source even in the 21st century. In 2011 alone, total output rose from 420 million t to around 6.6 billion t. Similar growth rates are also expected for the next few years. In order to meet demand, new seams are being tapped and others mined far more extensively. In most cases, this means a move from open-cast to deep mining, and extracting coal from ever greater depths. At the same time, extraction processes such as the room and pillar method are being replaced by longwall mining, which significantly increases seam yield and therefore output. The depth of extraction with new, modified mining methods is increasing rapidly around the world - in most countries, much more rapidly than the corresponding expertise. A trade in mining expertise has therefore developed alongside the coal trade proper. Germany relies on coal imports, but can export mining industry services and advanced mining equipment. Geological conditions in the Ruhr and Saar coalfields forced Germany to drive forward development of deep working for hard coal years ago. For 30 years now, Germany has been mining hard coal at depths of over 1,000 m, and excavation is now at depths up to 1,600 m. Deeper extraction and more extensive excavation posed new challenges for both miners and equipment. Intelligent logistics, modern roadway development methods and longwall mining with ploughs or shearers combined with optimised process coordination offered pioneering solutions - solutions to enable costeffective coal extraction in the long term without compromising safety. Countries such as Russia, the Ukraine, China and the Czech Republic, where extraction is now reaching similar depths, can now benefit from this experience: they do not need to go through the same process of trial and development, but can draw on Germany's findings and ultimately save on costs. Now, Germany is offering this knowledge and experience on the international market on a client- and deposit-specific basis to continue providing mining countries with safe and cost-effective coal mining solutions and secure the energy supply. The presentation gives a number of examples of how international mining companies have used expertise from Germany to better meet the challenges of deep mining.

Aug 1, 2013

By Utley Wedge

(Cleveland :Meeting, October, 1012.) In general, the art of securing copper from sulphide ores or concentrates may be said to consist of : (1) separation, in the molten state, of copper sulphide with some iron sulphide, from the great bulk of gangue-material, followed by (2) elimination of sulphur and iron from the molten matte, by oxidation and fluxing, leaving metallic copper. The definition is made broad enough to cover the general practice, whether or not the ore or concentrate is given a preliminary roast for the removal of surplus sulphur. The above process, which I will designate as the smelting process, makes necessary the presence in the ore, or the addition thereto, of such silica, lime, and iron as may be necessary for the formation of a light and fusible slag, together with sufficient sulphur and iron for the formation of copper-matte, and also the addition to the matte of sufficient silica for the oxidation and fluxing-out of the iron. These items, together with the cost of fuel sufficient for melting the mass, constitute important items of cost in the copper-smelting process. Numerous cases where fluxing-materials are scarce or dear, or where fuel is expensive, have caused special attention to be given recently to the wet process of copper-extraction, which may be designated as consisting of forming soluble copper salts which are then washed or leached out of the ore or concentrates by dissolving in water or acid. Metallic copper may then be secured from the solution of copper salts by electrolysis; by cementation; or copper can be brought out of the solution as a * Presented also at the Joint Meeting of the Institute and Section IIIa, Metallurgy and Mining, of the Eighth International Congress or Applied Chemistry, New York, N. Y., September, 1912, and here published by mutual agreement.

Dec 1, 1912