Search Documents

By Weston Bourret

The need for wartime supplies of uranium for the Manhattan Project prompted a 1944 study of uranium in South Africa. Uraninite had been reported by R.A. Cooper in 1923 in a Witwatersrand heavy- mineral concentrate, and the search for uranium, therefore, included the district's 30 operating mills. The method of investigation was simple: take bulk concentrate samples from the Wifley tables and determine their mineralogy. Samples were taken on a daily basis, although weekly composites also were taken of some mills. In 1944, most mills had simple gravity circuits and produced (I) a gravity concentrate, and (2) an all-slime [-75 pm (-200 mesh)] product. The tonnage throughput was known, and from that, head assays could be calculated. Concentrate samples were sent to the United States for chemical analyses. A Geiger counter set up in a Johannesburg hotel room provided preliminary data. The early data showed uraninite to be widespread. Microscopic, mineragraphic, and siezing tests were all under- taken in Johannesburg. Ultimately, tests led to a high grade (+90%) uraninite concentrate. Platinum and other heavies were the impurities. In seven months, the investigations had reached the stage where it was possible to forecast an annual production of 5.4 to 7.3 kt (6,000 to 8,000 st) of U3O8. The estimate is still realistic. Additional details are found in Bourret (1981).

Jan 1, 1991

By Marcos Vieira, Gil Vilela, Wanderson Silvério, Livia Faustino, Pierre Fernandes

New global industry standards and regulatory changes regarding mining tailings management are driving installation of tailings filtration plants to decommission existing tailings dams and implement dry stacking. Target of this project was to reduce ultrafine slime tailings deposition. Previous investigation at Samarco concentrator has showed a 35% decrease in tailings filtration throughput when feeding a mix of 95% flotation tailings with 5% slime tailings (compared with 100% flotation tailings), also worsening geotechnical aspects such as material workability during dry staking. Industrial trials using a proper filter aid at tailings filtration plant feeding a mix of 94% flotation tailing and 6% slime tailing (equivalent to 30% of total slime generation) have provided filtration performance maintenance (throughput and cake moisture), and dry stacking the dewatered material. Results achieved will enable life expansion of existing slime disposal structures, as well as potential life of mining extension. Furthermore, reagent chemistry influence is discussed by the light of geotechnical aspects, which has been showing improved KPIs, such as workability, compressibility and permeability.

Feb 1, 2025

By Richard H. Bares

One criterion central to most definitions of reclamation is the restoration of mined lands to their original productive potential. This is often difficult to achieve on mined lands in the Northern Great Plains because of the rigorous climate (Bares 19;2) and various soil related problems including sodicity, salinity, soil permeability, low organic matter and plant nutrient deficiencies (Malakondaiah and Safaya 1982). Field study sites were established on recontotured mined areas during the early 1970's (prior to the topsoil mandate) in which several amendments were tested for their ability to improve spoil/topsoil conditions and, hence, increase plant production. Physical and chemical properties of these control (untreated) and amended spoils and topsoils have been summarized (Safaya et al. 1982). A number of grass and legume species combinations were studied. The general effects of one time (prior to seeding), single rate (approximately 100 mT ha-1) application of leonardite and/or slack coal to spoils and topsoils was the reduction of grass dry matter yields (NB 1 test site: dry matter yield (DMY) without slack was 110 g m 2 yr I ; DMY with slack was 80 g m -2 yr 1 I and the promotion of legume establishment and yield (SB test site: DMY without leonardite was 13 g m 2 yr -1; DMY with leonardite was 93 g m 2 yr 1). On South Beulah topsoil, treated with leonardite, production of weedy species was remarkably lower than that without leonardite (SB test site: DMY without leonardite was 252 g m - yr -1; DMY with leonardite was 177 g m 2 yr 1). The general effect of commercial fertilizer applied one time prior to seeding (rates ranging from 9-13-0 to 44-1 12-28 kg ha-1 of N-P-K) was to increase plant production during the first two to three years after which the effect disappeared. This effect was much more pronounced on spoils (NB I test site: DMY on spoils without fertilizer was 53 g m -2 yr -1; DMY on spoils with fertiliser was 132 gm -2 yr -1). Weedy species accounted for most of the biomas, production during the first growing season. Three of the test sites were designed to study plant production on topsoils and spoils. Establishment and production of grass species were comparatively better on topsoils (30 cm in depth) than on spoils while legumes were most successful on the soils (Center test site, 1979; DMY of grasses on topsoil was 170 g m 2 yr -1 DMY of grasses on spoils was 52 g m -2 yr -1; DMY of legumes on topsoil was 20 g m -2 yr -1; DMY of legumes on spoil was 191 g m 2 yr -1). Total plant production on topsoiled (302 m thickness) plots at the South Beulah site (DMY in 1979 of 269 g m 2 yr 1) was comparable to that of native western wheatgrass prairie (DMY of 262 g m -2 yr -1). An experiment was conducted to find out if time of planting would have any effect on establishment of grasses on spoils. It was fund that late fall seeding was superior to spring planting for establishment of wheatgrasses at NB 3 test site (Control Plot, 1975: DMY on spring-seeded was 1 g m -2 yr - 1; DMY on fall-seeded was 55 g m -2 yr -1). In general, wheatgrasses (slender, streambank, thickspike and western) yielded the most aboveground biomass of all the grass species tested; yellow sweetclover was the most successful legume. Yellow sweetclover established and was productive on both spoils and topsoils but only where competition with grasses was apparently minimal. Durar hard fescue established and thrived on topsoil but dry matter production was low compared to that of wheatgrasses. Emerald crown-vetch demonstrated a potential for growth on spoils where water conditions were adequate, whereas side-oats grama, prairie sand-reed, alkali sacaton, and bird's -foot trefoil demonstrated only sporadic success. Little bluestem did not become established at any of the test sites. Peak production of the planted species, especially grasses, was generally reached by the second week of July. Legume and weed production continued to increase into late August.

Jan 1, 1982

By Xu Weihong

After being pre-treated, composite electro-deposits of semi-bright nickel/nano-SiO2 with bright nickel or with amorphous Ni-P alloy, and Composite electro-deposits of Zinc were prepared on Nd-Fe-B magnetic material. The effect of cathodic current density, nano-SiO2 concentration, stirring strength and surfactants on the corrosion resistance of electro-deposits were studied. In addition surface appearance and structure of the composite coatings were analyzed by SEM. The present investigation shows that the corrosion resistance of composite electro-deposits of semi-bright nickel/nano-SiO2 with amorphous Ni-P alloy was the best, the solution system of semi-bright nickel/nano-SiO2 with bright nickel was stable and its electro-deposits also had an excellent corrosion resistance, composite electro-deposits of Zinc not only had good corrosion resistance, but also low cost, thus making it an excellent electro-deposit for medium or low-class Nd-Fe-B magnetic material.

Jan 1, 2006

By Neil O. Johnson

In the cyanidation of gold, silver and mixed ores, the solids, suspended in the pulp after fine grinding, primary settling and scries agitation arc subjected to a washing step known, generally, as countercurrent decanta-tion, abbreviated C.C.D The conventional C.C.D. plant consists of a series of separate thickeners—three to five in number—arranged in series on slightly different elevations. Solids settled in the first thickener are pumped at maximum density into the second thickener, where they arc diluted with weak solution overflowing the third. After settling in the second thickener they are pumped to the third, where the process of repulping with still weaker solution is repeated, and so on throughout the system, until they reach the last thickener and are repulped with barren solution or water. Recently there has been developed a new type of thickener, known as the Dorr Washing Tray Thickener, consisting of up to five individual thickeners, which performs in a single unit all the functions of a conven-tional C.C.D plant. Fig. 1 illustrates the essential features. It is a multicompartment tray thickener, in which the trays operate in scries instead of in parallel for countercurrent washing. Feed enters the top compartment via a central, semisubmerged feed well. Strong solution overflows into a peripheral launder. Solids settle to the bottom, are raked to the center and flow into the top of the second compartment, directly below, via an inverted cup and scal. Solids pass downward, compartment by compartment, against a counter flow of wash solution and finally of fresh water. Thus, in accord-:trice with the basic C.C.D. principle, the solids transfer the dissolved metal content to the wash solution and finally are removed by a diaphragm pump from the bottom compartment virtually free of valuable material. Similarly, the wash water, as it flows through the system, becomes increasingly enriched in dissolved metal until it overflows from compartment two and returns to the process.

Jan 1, 1939

By Neil O. Johnson

In the cyanidation of gold, silver and mixed ores, the solids, suspended in the pulp after fine grinding, primary settling and scries agitation arc subjected to a washing step known, generally, as countercurrent decanta-tion, abbreviated C.C.D The conventional C.C.D. plant consists of a series of separate thickeners—three to five in number—arranged in series on slightly different elevations. Solids settled in the first thickener are pumped at maximum density into the second thickener, where they arc diluted with weak solution overflowing the third. After settling in the second thickener they are pumped to the third, where the process of repulping with still weaker solution is repeated, and so on throughout the system, until they reach the last thickener and are repulped with barren solution or water. Recently there has been developed a new type of thickener, known as the Dorr Washing Tray Thickener, consisting of up to five individual thickeners, which performs in a single unit all the functions of a conven-tional C.C.D plant. Fig. 1 illustrates the essential features. It is a multicompartment tray thickener, in which the trays operate in scries instead of in parallel for countercurrent washing. Feed enters the top compartment via a central, semisubmerged feed well. Strong solution overflows into a peripheral launder. Solids settle to the bottom, are raked to the center and flow into the top of the second compartment, directly below, via an inverted cup and scal. Solids pass downward, compartment by compartment, against a counter flow of wash solution and finally of fresh water. Thus, in accord-:trice with the basic C.C.D. principle, the solids transfer the dissolved metal content to the wash solution and finally are removed by a diaphragm pump from the bottom compartment virtually free of valuable material. Similarly, the wash water, as it flows through the system, becomes increasingly enriched in dissolved metal until it overflows from compartment two and returns to the process.

Jan 1, 1939

By Leahy G. J, Moxon N. T, Nicol S. K

Experimental work is described in which extremely dilute aurocyanide liquors are treated with novel surface-active complexing agents to produce a hydrophobic aurocyanide species. Subsequent aeration of these liquors causes accumulation of such species at the air-water interface and the aurocyanide complex is transferred to a froth concentrate. A detailed performance assessment of this process is made and this knowledge used in the design of a pilot plant facility. Early results indicate the feasibility of the selective recovery of aurocyanide ions from reclaimed residue dam water (approximately 0.2ppm Au) with upgrade ratios of the order 180:1. A further study was made applying ion flotation to the recovery of gold from a carbon-in-pulp (CIL) feed liquor (approximately 1.0ppm Au). The probable economics of this process compared to conventional CIL processing is also described. Successful development of countercurrent ion flotation for concentrating solids-free gold solutions may offer a lower cost alternative to existing gold ore processing technologies, or in more secondary applications such as concentrating dilute gold solutions or heap leach runoff. The technology may also have more generalised applications to other heavy metal process- Ing.

Jan 1, 1991

By Stefan Mutz, Thomas Pretz, Jörg Julius, Frank Hilbk-Kortenbruck, Aachen, Hartmut Harbeck

"The annual global production of primary aluminium was about 22 million tons in the year 2000. This represents the second largest production rate in the world market after steel. Experts are predicting that the global demand for aluminium will rise in the near future.In contrast to other metals such as copper, the recycling of aluminium is considered relatively difficult. There are two main alloying groups, namely cast and wrought. In the case of aluminium it is important that the constituents within the scrap aluminium to be smelted are clearly identified. Within the secondary remelting process alloying does take place, but a removal of unwanted metal constituents is problematic. Therefore mixed aluminium scrap (not genuine in-house collected material) can only be used to produce cast aluminium. Thus, in other words a down-cycling of wrought (extrusions and rolled) products occurs. However, in spite of these difficulties there is an increasing trend to produce aluminium from secondary scrap (approx. 35% in Germany). Similar trends have been identified in the USA and other industrialised countries. This development is mainly caused by the high energy consumption for the production of aluminium from bauxite. Producing aluminium from scrap is saving about 95 % of the energy in comparison to the processing of primary raw materials.An improvement in sorting technology is necessary to separate wrought and cast alloys of aluminium as the absolute amount of recovery from old scrap is higher than the demand for cast.This contribution presents some alternative methods, utilizing automatic picking technologies, which will be used to separate secondary aluminium in the future. During the recent years, some major progresses have been made in automatic picking technologies for different applications in the processing of primary and secondary materials.For the sorting of aluminium scrap a special additional sensor will be necessary. The best detection will ultimately be based on online elemental analysis of single particles. First investigations in the field of laser based systems for these applications have already been performed several years ago. One of the laser based techniques is the laserinduced breakdown spectrometry (LIBS)."

Jan 1, 2003

By John Olivera

El objetivo principal, es mejorar la preparación y el minado mecanizado de las Operaciones, de los resultados de minados de la variante del Sub Level Stoping, se genera el método AVOCA, una combinación con el Cut and Fill Stoping tradicional y en los avances el uso de detonadores electrónicos con el objetivo de realizar un método de segregación en los sub niveles (2.8m ancho x 3.8m altura) que se adapta al minado en Vetas Angostas, con una mejora que es el uso de Micro - Equipos Trackless (Equipos de bajo perfil menores a 2.0 m de ancho) en cada proceso de la operación unitaria. Con este método de minado y los equipos diseñados para labores angostas se mantiene y controla un límite máximo de abertura, en la preparación y en el minado.

Sep 30, 2022

By Kaustubh Joshi, Pradip, Beena Rai, Venugopal Tammishetti

"Rapid depletion of high grade iron ores coupled with the increasing demand for the blast furnace grade iron ore in recent times has shifted the research focus on the development of appropriate technologies for the utilization of low - grade alumina rich iron ore slimes. These slimes are currently being dumped into tailing ponds owing to their high alumina content. Typical constituent minerals present in the Indian iron ore slimes are hematite, goethite, gibbsite and kaolinite. Considering the fine particle size distribution (<37 microns) in the slimes, selective dispersion-flocculation seems to be one of the most appropriate process which has been explored by us. We present our successful results on a natural iron ore slime sample obtained from one of the mines in India. We have been able to achieve a concentrate assaying >67% Fe, and <3% Al2O3 and 2.8% loss on ignition (LOI) from the slime sample assaying 60.4% Fe, 7.7% Al2O3 and 5.45% LOI with an Fe recovery of 62-69% simply by adjusting the pulp pH. We have scaled up the process to a semi batch scale as a prelude to commercialize it for the beneficiation of low grade iron ore slimes."

Jan 1, 2014

By Dale C. Matthews, Donald L. Simpson

Hecla Mining Company&apos;s Lakeshore Mine and Metallurgical complex near Casa Grande, Arizona, is the first plant in North America to utilize the roast/leach/electrowinning process for production of cathode copper from sulfide concentrates. Oxide copper ores are also mined at Lakeshore. Using sulfuric acid and sponge iron by-products of the roast/leach operation, the oxide ore is leached in vats, the copper is precipitated with iron and recovered as cement copper. This paper will describe the roast/leach facilities and discuss the operating conditions at which more than 95 percent of the copper in concentrate is made soluble in acid solutions while less than 5 percent of the iron is rendered soluble. More than 97 percent of the sulfur contained in concentrate is captured either as strong sulfuric acid or as soluble sulfates in leach liquors. The iron rich residue after leaching is pelletized and reduced to sponge iron in an SLRN reduction kiln.

Jan 1, 1981

By Yu AB, Azahari HL

Indonesia has the largest coal reserves in the south-east Asian region. According to estimates from the World Energy Confer- ence, it has reserves of 18 billion mt lignite, 4.4 billion mt sub-bituminous coal and 774 million mt bituminous coal (Wyllie,1988). In recent years, substitution of coal for oil in power plants has been the goal of the Indonesian government since proven deposits of coal are about five times as large as national hydrocarbon reserves and most of Indonesia&apos;s power stations are still oil fired. Recently a coal fired power plant has been built in Java Barat, which will have a full capacity of about 3000 MW. It is intended to supply coal for this power plant from Bukit Asam mining area (South Sumatra). Coals from Bukit Asam - which are of the lignite or brown coal type - usually contain considerable moisture . It should be noted that reference to moisture in coal pertains to the total moisture content. This is comprised of what is commonly termed as equilibrium moisture and surface moisture. Surface moisture typically affects combustion process as well as pulveriser performance since it possibly influences the relative ease with which coal may be ground. In practice, the surface moisture produces agglomeration of the fines in the pulverising zone and reduces pulveriser drying capacity because of the inability to remove the fines as quickly as they are produced. This agglomeration has also the same effect as coarse coal during the combustion process because the surface area available for the chemical reaction is reduced, hence the combustion efficiency is also reduced. The influence of the moisture of some coals on their grindability (Hardgrove Grindability Index) has been previously correlated by several authors; some of them will be mentioned later. Those correlations, however, could not be immediately applied to any coal since it is still believed that there are other factors which influence the grindability of the coal, such as type and rank of the coal. The relationship between coal moisture content and its grindability has been investigated by Ellmann and Belter (1955). It was found that, for North Dakota lignites, the grindability varied as the moisture content changed. In Britain, Fitton, Hughes and Hurley (1957) stated that, for Bilsthorpe coal, over a wide range of free moisture content (from air-dried to about 30 per cent moisture), the Hardgrove Grindability Index (HGI) remains virtually unchanged. In addition to that, it was suggested that it would be slightly advantageous to dry the coal below its air-dried moisture content (at temperature ¦ 100¦C) to increase the ease with which coal could be ground, especially for low-volatile coal and high-volatile non-caking coal. Furthermore, it was also concluded that a broad relationship appeared between coal rank and Grindability.

Jan 1, 1993

By M. Frenzel, D. Ebert, K. Bachmann, A. D. Renno, R. Möckel, J. Gutzmer, J. Krause

With the increasing demand for metalliferous and mineral raw materials, and consequent depletion of the global natural resource base, the possible utilization of secondary raw material sources is receiving more and more attention. In the present study, we present results from a detailed vanadium deportment study of three basic oxygen furnace slag (BOS) samples known to containing elevated bulk concentrations of vanadium (V). Complementary analytical methods that were used to quantify the abundance and composition of V-containing phases include SEM-based automated mineralogy, Xray fluorescence (XRF) analysis, and X-ray powder diffraction as well as electron probe microanalysis. The vanadium deportment was quantified using Monte-Carlo simulations of the data obtained from automated mineralogy and electron microprobe analysis. The total V concentrations identified by XRF are between 1.7 and 2.2 weight percent V. The most important hosts of vanadium are larnite-, brownmillerite- and portlandite-solid solutions. In two samples, calcium carbonates also significantly contribute to the V deportment, while wuestite, lime and native iron do not contribute significantly to the vanadium deportment. A thorough consistency check identifies considerable uncertainties in the density of the Vbearing phases as the most likely reason to explain remaining discrepancies between measured and calculated V values.

Aug 1, 2024

By Hang G, Hongtian X

In this paper, it is briefly introduced that China&apos;s Ordovician limestone confined-water menaces coal mining and Ordovician water is prevented and cured to secure the safety of coal mining. The theory of "Down-Three-Zones" is presented on the basis of research and practice in recent ten years. The concept of "Down-Three-Zones" of floor water-eruption is described clearly. Finally, the principle and method of applying the theory of "Down-Three-Zones" are discussed. 1. An Introduction of Damage: China is rich in coal resources. The conditions of coal field geology are quite complicated. There is an area of two million square kilometre of Karst limestone in nine million six thousand square kilometres of territory. The resources of underground water are rather plentiful, but this menaces coal exploration. Sixty percent of coal mines in China are damaged by limestone confined-water in different scales, particularly coal mines located the Carboniferous-Permian coal fields of the Ordovician limestone distribution area of Northern China. Because there is the 500-800 metre thickness of Ordovocian limestone and the well developed Karst containsl plentiful water, Karst water can have more than 100 Kg/cm pressure. Limestone aquifers have only distances of several metres or several decade metres to coal seam, Karst water can enter the aquituge and even the coal seam, large eruptions often occur. For example, a mine of 3 million ton production capacity had an eruption of 2053 cubic metres per minute. This is the largest confined-water eruption which has brought enormous economic damage and threatened the safe production of coal mining. Therefore, the prevention and cure of Ordovician water has immense advantage to the development of the coal industry. There are several decades experience in the prevention of Ordovician water-eruption in China. The prevention of Ordovician water-eruption has two kinds of plans. 1) dewatering and depression: it refers to dewatering of aquifers as roofs of seam and depression of aquifers as floors of seam in mining areas. 2) comprehensive prevention under the condition of having water pressure in aquiters. Due to enormous water, electricity, equipment and lots of other factors, the former isn&apos;t used extensively, the latter tits to China&apos;s actual conditions and is used widely. So-called comprehensive prevention under the condition of

Jan 1, 1988

By C. T. Sheeran, J. C. Franklin

A commercially available microprocessor-based system capable of monitoring 512 channels has been interfaced with monitors for radon, working level, air velocity, and fan power. The basic system utilizes both 280 and 8080 microprocessors in a desktop central processing unit (CPU). CPU hardware includes keyboard, video display (CRT), and disk drive; a printer is used to keep permanent data records. Signals from all channels are transmitted to the computer in digital form where they are processed for alarm status. Software developed for the system allows for audiovisual alarms in the event of low and high readings, rate change, change of state, or communica- tion failure. Up to six channels can be continuously displayed on the CRT for current readings. Shift reports and trend logs may be generated to help the ventilation engineer determine average working levels and ventilation effectiveness. Additional software permits the operator to program command sequences which may be used to automatically restart fans after a power outage.

Jan 1, 1982

By Edward A. Mihok

This paper presents plant design and cost estimates for limestone treatment of acid mine water covering a wide range of quality and quantity conditions. The treatment process consists of limestone neutralization, aeration, solids settling, and concentration. The design criteria for the various operation functions are based on pilot plant performance, laboratory data, and established mine water treatment standards. Unit costs have been assumed and are related to general market prices and conditions. These estimates serve as preliminary indicators of what it would cost to construct and operate a mine water treatment plant.

Jan 1, 1970

By Bigdy D. N

The paper describes a system for providing mine management with a continuous indication of the effectivness of longwall coalface powered supports in controlling roof-to-floor convergence. The system comprises on-face instrumentation monitoring convergence and support leg circuit pressures, a means of transmitting the output of that instrumentation to the surface for collection, and software which presents both a condensed analysis for rapid review of the current state, and extended analyses from which remedial action can be recommended if a problem is identified. The results of a field trial are presented showing that meaningful results can be obtained.

Jan 1, 1988

By William M. Baldwin, T. S. Howald, A. W. Ross

EXPLORATORY WORK THE related subjects of preferred orientation, directionality in physical properties, and earing tendencies of wrought metal [ ] strip have attracted the attention of metallurgists to such an extent that in the past 20 years hundreds of researches have been published on this one general problem. The anisotropy of tensile strength and elongation have been exhaustively studied in their relationship to the occurrence of ears in cups drawn from strips-20.29 and, to a lesser extent, yield strength7,11,17 and stress-strain curves" have been investigated. Despite the tremendous fund of knowledge thus accrued, no simple quantitative correlation of directionality and earing tendencies has yet been found. In a sense, this is not surprising. The formation of ears in a drawn cup clearly is a special phase of the general study of metal flow; in particular (as will be brought out in the course of this paper), ears are due to anistropy in the rates of deformation of the metal in the radial, circumferential, and "thickness" directions of the original blank. It would be difficult to effect a correlation between earing tendency and a property that may be completely independent of the flow of metal, or at best related to metal flow in an exceedingly complex fashion. Yet, it is this correlation that has been attempted; tensile strength and elongation are attributes of metal rupture, a phenomenon that has quite admirably been shown to be distinct from the phenomenon of metal flow,21 while yield strength and stress-strain

Jan 1, 1945

By R. Barbaroux, B. Dubreuil, D. Lemieux, K. Nasrallah, G. Garcia Curiel

"As conventional, base or precious metal ores are being depleted worldwide, the mining industry is being faced with an increasing exploitation of arsenical sulfidic ores. Enargite is a common example. The downstream processing of these ores poses several problems ranging from high smelter penalties to finding economical and environmentally acceptable means of disposing of the arsenic. Several hydrometallurgical processes have been proposed for extracting arsenic from enargite concentrates, notably using alkaline sulphide leaching (ASL). However, few alternatives exist for removing the arsenic from solution and stabilizing it in an approach that is both economical and environmentally acceptable.Dundee Sustainable Technologies (“DST”) has developed a technology for the sequestration of arsenic by vitrification. Originally optimized to cost-effectively stabilize arsenic trioxide (As2O3), DST has shown that vitrification could be successfully extended to the stabilization of other arsenical products, such as calcium arsenate (Ca3(AsO4)2) and sodium arsenate (Na3AsO4). In this paper, the vitrification of arsenic in the context of an enargite leaching was newly explored and demonstrated successfully.Two processing routes are being proposed by DST for the removal of arsenic from enargite concentrates and their stabilization by vitrification. In one route, arsenic is extracted by ASL and is then precipitated under atmospheric conditions and with minimal use of reagents and time. The resulting precipitate is an unstable hydrated ferric arsenate (FeAsO4•2H2O) that is then vitrified in a non-dilutive method, significantly increasing the stability of arsenic and meeting the TCLP guideline. Unlike is required for scorodite, stabilization was successfully achieved without concern for the crystallinity of the precipitate."

Jan 1, 2017

By Gregory Abramov

Borehole Mining (BHM), a remotely-operated waterjet mining method (Figure 1), has recently achieved two major milestones. It was, for the first time, applied to the extraction of manganese ore and at temperatures below freezing. The 1St stage is a demonstration test that is now underway just north of Emily, Minnesota, where the manganese ore is located 100-160m below the surface and its reserves are estimated to be in excess of 500,000 tons. The deposit was discovered over 60 years ago but, due to the fragile and sensitive nature of this Land of 10,000 Lakes (nickname for the State of Minnesota) and strong environmental restrictions, the iron/manganese reserves were deemed unrecoverable and remained untouched until late 2010 when permission for a single-hole demo-test was issued by the local Department of Natural Resources.

Jan 1, 2011