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By S. Mathur, Pradip

Polyacrylic acid (PAA) was evaluated as a selective flocculant for the dolomite-apatite system. PAA with a molecular weight (MW) of 4 million was found to flocculate both dolomite and apatite. However, the flocculation behaviors of dolomite and apatite were significantly different with 450,000 MW PAA, which was found to be the lowest molecular weight fraction capable of flocculation. In single-mineral tests with a dosage of 2 kg/t PAA, 90% of the dolomite and 35% of the apatite flocculated. Selectivity was achieved in mixed mineral tests. From a feed consisting of an 80:20 mixture of apatite and dolomite, respectively, a concentrate containing 90% apatite was obtained with a 70% recovery. The dolomite rejection was about 75%, which corresponds to a 2% MgO content in the concentrate.

Jan 1, 1997

By Barbara C. Williams

U.S. Bureau of Mines researchers conducted field studies at an abandoned copper-gold mine tailings impoundment. Pore water quality was analyzed in the vadose and saturated zones. Three statistical procedures were employed to summarize the variability within and between the two zones. The results indicated that linear combinations of those variables reflecting sulfide oxidation and aluminum-silicate weathering best summarized the variability in each zone, and that the zones were most different on the basis of sulfide oxidation variables. The geochemical computer code WATEQ4F was used to assess the solubility status (saturation index) of minerals. Saturation indices of sulfide oxidation and aluminum-silicate weathering minerals were different in the two zones. It was demonstrated that the statistical analyses produced similar and complementary results to the geochemical code.

Jan 1, 1992

By Michael L. Maniocha

Most magnesia (MgO), whether of natural or synthetic origin, is used in the dead-burned or periclase form as refractory linings for the production of steel. Continued research in refractory science, combined with good refractory maintenance and improvements in steel-making processes, have resulted in decreased use of magnesia. To make up for this loss of business, producers of synthetic magnesia have started to manufacture a variety of magnesium-based chemicals that are used in many industries. There are three primary methods of producing MgO. The first involves the calcination of naturally occurring minerals species. Most of the magnesia produced by this method uses the rhombohedra1 carbonate mineral magnesite, MgCO,. To a lesser extent, the mineral brucite, Mg(OH), is calcined to magnesia. Magnesia produced by the calcination of minerals is called natural magnesia. The second production method uses magnesium-rich brines, or sea water reacting with lime or calcined dolomite to produce magnesium hydroxide. The magnesium hydroxide is subsequently calcined to magnesia. Material produced in this way is called synthetic magnesia. The third major method of production uses saline lake brines to produce magnesium chloride. Magnesium chloride brine is sprayed into a reactor where it thermally decomposes into MgO and HCl. The magnesia is purified by slaking to magnesium hydroxide followed by calcination. Magnesia produced in this manner is also know as synthetic magnesia (Duncan and McKracken, 1994). The degree to which the magnesium minerals or the synthetically prepared magnesium hydroxide is calcined governs the physical properties of the resulting MgO. It is the physical properties that dictate the end use for the product. The terms used to describe magnesia vary along with the degree of calcination. Table 1 summarizes the terminology used when discussing the various forms of magnesium oxide.

Jan 1, 1997

By Burt Ensley, Viatcheslav Dushenkov, Ilya Raskin, David E. Salt

Roots of many hydroponically grown terrestrial plants, including sunflower (Helianthus annuus L.) effectively remove toxic metals such as Cu+2, Cd+2, Cr+6, Ni+2, Pb+2 and Zn+2 2 from aqueous solutions. It should be possible to scale up this process such that plant roots can be used to treat large volume aqueous waste streams. It can be extrapolated from laboratory results that to reduce the Cd concentration in a waste stream, from 1 ppm to below 4 ppb, with a flow rate of 4000 L/min, would require 3500 sq. m of plant roots with a density 5 kg fresh weight per sq. m. These results suggest that the roots of hydroponically grown terrestrial plants may provide an attractive alternative to the accepted water treatment technologies.

Jan 1, 1995

By T. G. Carnahan

The U.S. Department of the Interior, Bureau of Mines, performed a laboratory-scale investigation of technique for recovering silver from pregnant solutions generated in the hydrometallurgical treatment of complex base-metal sulfide concentrates with oxidizing chloride media. This provides a means for recovery and simplified reduction of accessory silver to metal from ions. The method consists of adding NaI or KI to the solution to precipitate AgI, which is then contacted with Na2S to produce Ag2S and to regenerate the iodide salt solution. Silver recoveries range from 99 pct with 20 pct excess iodide precipitant, to-92 pct when the theoretical stoichiometric amount of precipitant is employed. The Ag2S product can be reduced to silver metal by contact with aluminum chips in NaOH solution followed by purification with conventional fire refining techniques.

Jan 1, 1980

By Wayne Wride, Amy Lamb, Debra Sonntag

In today's "information age", we have the ability to collect volumes of data about a company's performance. The challenge is to turn that data into information employees can understand and use to fine-tune equipment, modify work processes, and ultimately manage production. Software programs have increasingly given end users control over what data is used and how it is presented. Kennecott has implemented an information system capable of collecting and storing data at the primary level. This enables plant personnel to transform historical data into information for action. Kennecott plans to expand its data collection and use trending and reporting capabilities to move toward a fully optimized operation.

Jan 1, 2000

By Thomas S. Mackey

The industrial types, sources, and quantities of USA tin residues are identified and the methods of treatment reviewed. The effect of a lower tin price, due to a current major world surplus of tin metal, is mentioned and covered in some detail. The names and locations of over 100 USA firms recovering tin residues are listed. Current smelting and refining charges are included to convert the residues into tin metal and alloy. The impact of the suspension of the LME daily tin price since October 24, 1985 to date, and the failure of the International Tin Council to support the Buffer Stock Manager are reported with comments.

Jan 1, 1986

By William F. Abercrombie

The role of the laboratory is described in relation to the prospecting and exploration of kaolin clays. Test methods used to evaluate crude ore samples of kaolin clay for commercial consideration are reviewed. A background of the kaolin mineral and known means of prospecting this mineral are presented. Common analytical methods are discussed with special emphasis on those in use today.

Jan 1, 1982

By Sam M. Pickering

Most high, purity silica is produced from crystalline quartz-generally from sand. However, there is a small area of southern Illinois where a porous, friable white chert rock is found which is very different in physical form from quartz sand. This microcrystalline material, commonly referred to as tripoli, is more easily ground to micron sizes than sand. Although of similar Moh's hardness, microcrystalline tripoli is less abrasive than either ground quartz sand or many synthetic abrasives. Location The southwestern corner of Illinois is underlain by extensive deposits of very porous chert; in some places the material is quite white. Two companies - Illinois Minerals Co. and Tammsco, Inc. - mine and process this white material. The Illinois Minerals plant is located at Elco, and the Tammsco plant is in Tamms, Illinois. Both companies mine from various locations within a ten mile truck haul of their plants. Production from this district has been continuous since at least 1915. Malvern Minerals Company mines and processes a generally similar microcrystalline, friable novaculite near Hot Springs, Arkansas.

Jan 1, 1985

By John Bailey

Stressmap is a program whereby the earth's stress field is charted in detail and utilized for design of mines and mine exploitation. This program is implemented by mapping the attitude (location, direction, dip, and extent) of induced rock ruptures during the process of hydrafracturing drill holes contiguous to mine interest. The program includes utilization of ancillary naturally occurring stress relief signals, They are precipitated because the earth is indeed dynamic and the strata of the crust are continually adjusting to load and/or strain differentials resulting in rock deformation and fracturing. These fracturing adjustments occur as small to tiny earthquakes comparable to Richter magnitudes of one, zero, minus one, and smaller events termed microearthquakes. Obviously, the earth's stress field changes due to continued differential loading and crustal movements; therefore it becomes conspicuously evident that resolving today's stress field as opposed to paleostresses is most important for efficient, economical, and safe mining operations.

Jan 1, 1974

By J. A. Herbst, C Lo. Y, Z. Rogovin

The identification and quantification of incipient overload conditions in mills have recently been found to be very significant in the design of tumbling grinding mills. To investigate these phenomena, a series of experiments was conducted in a Plexiglas mill operated in both dry and wet modes. For on-stream measurement of the mill charge weight, volumetric filling, dynamic angle of repose, and mill power, an electronic system was developed. The mill was filled to various levels with 19.1-mm (3/4-in.) ceramic balls as grinding media. As feed material, grindable limestone or 3.2-mm (1/8-in.) nongrinding ceramic balls were fed at various steady-state rates to determine the incipient overload conditions. The prediction of overload has apparently been reduced to predicting the feed rate that results in 50% mill filling.

Jan 1, 1988

By B. Schimm

Improve the mines productivity by simplifying the mining process, for these tasks the Wirtgen Surface Miner offers an attractive alternative. Surface Miners cut, crush and load material in one operation with only one machine. The cutting depth is controlled exactly.

Jan 1, 1997

By Clifford R. Porter

A 200 pound per hour Magnex Pilot Plant was designed and constructed. A non-compliance Eastern Coal which would generate more than 2.0 lb of SOZ per million Btu upon burning was brought into compliance (less than 1.2 lb of S02 per million Btu) during continuous operation of the pilot plant. Approximately 85 percent of the pyritic sulfur was removed while recovering 86 percent of the Btu of the feed coal. Pilot plant operation is summarized and preliminary economics presented. Present status of the Magnex Program is reviewed.

Jan 1, 1977

By Richard M. Crowell, John W. Shield

GeoBiotics has developed a biooxidation technology (patents pending) which involves coating refractory precious metal sulfide concentrates onto a support material and biooxidizing the sulfides in a heap configuration. The concentrates are produced from low or high grade sulfidic refractory ores or existing mine tailings. The process has been found to achieve high gold recoveries asso­ciated with stirred tank biooxidation, but at the low operating and capital costs associated with whole ore heap biooxidation. Improved gold recoveries of up to 98% after biooxidation are reported for 4 representative mines or deposits. The sulfide flotation concentrates were studied using 3 and 6 in. diameter columns or 3 in. drained vats. The refractory sulfide concen­trates biooxidize rapidly in 3 to 12 weeks with substantial increases in subsequent gold recovery.

Jan 1, 1996

By H. G. Linge

The Australian gold industry currently contributes some $4bpa to the national economy [l]. Some 40% of the total gold is produced in the region centred on Kalgoorlie known as the Eastern Goldfields of Western Australia. This region is the largest single centre of production with an output of some 100 tpa of gold [2]. In the Eastern Goldfields, refractory arseno­pyritic gold ore is an increasingly significant source of gold, feeding several operations utilizing bio-oxidation as the pre­carbon in pulp/leach (CIP/L) treatment process [1]. This paper desribes an alternative pre-CIP/L treatment option for use in the Eastern Goldfields based on the chlorination of arsenopyrite by chlor-alkali technology [3] using the salt resources available from saline water present in abundance in the region.

Jan 1, 1995

By S. J. Porter, M. T. McRae

The Melbourne City Link project includes two three-lane highway tunnels, 1.6 and 3.4km long, respectively, which are both approximately 16 meters wide and 9 meters high. The tunnels will be excavated through interbedded, moderately to highly jointed siltstones and sandstones of the Silurian Age Melbourne Mudstone formation over the major parts of their lengths. The strength of the intact rock varies from less than 5 MPa to greater than 70 MPa. Based on the available information regarding the performance of large span tunnels in weak rock, it was considered that the commonly applied empirical design guidelines for tunnel support, based on rock mass classification systems, should be augmented by more explicit design methods. The support design was, therefore, validated by analytical procedures, including numerical analyses, which are described in this paper.

Jan 1, 1997

By Didem Maral

Olivine is a name of a mineral group that has a chemical formula of: (Mg, Fe), SiO4. The most important rock for the olivine group minerals is dunite, which can contain olivine up to 95-99%. Dunite can be obtained from chrome enrichment as a by-product. As a result of alteration of the olivine group minerals, several kinds of different minerals can occur. Main consumption areas of olivine are steel and iron industry. Also olivine is used in not only casting and refractory industries but also production of radiator, ballast material and abrasive. North of Bursa-Orhaneli has got more than 5 billion tons reserves in ultrabasic massifs. M.T.A found that olivine has got high quality of using in refractory and casting industry.

Jan 1, 2005

By G. Brooks, J. T. Ellington, M. Yensco, G. E. Mcquien, M. T. Ityokumbul

Coarse silica flotation from intermediate pebble (IP) product has been carried out a pilot plant Dual Extraction Column (DEC) at an operational phosphate mine in Central Florida. The solids feed rate ranged from 4.16 – 5.3 TPH while the amine dosages ranged from 0.32 – 0.93 lb/T. The optimum amine dosage when using recycled process water was deter-mined to be 0.6 lb/T. With a feed containing 40-45 BPL and 38-45% insol, the results show that the IP can be upgraded to 56-61 BPL and insol of 16-22% at 85-90% BPL recovery. The results show that the DEC is an effective device for flotation of coarse silica from the IP. The advantages of upgrading the IP prior blending with the pebble are presented and discussed.

Jan 1, 2004

By Ph. Vandebrouck

SUMMARY In August 1986, TRANSMANCHE LINK, a joint venture comprising the 10 companies who initially promoted the project, signed a contract with EUROTUNNEL for the design, construction and commissioning of the TRANSMANCHE fixed link for an amount of 4,5 billion dollars. On the French side, the work consists of digging three, 19km. long tunnels, of which almost 16 kms. are under the sea, up to the meeting point with the Tunnel works carried out by the British.. The tunnels are bored through chalk by 5 tunnelling machines, starting from one intermediate point at Sangatte near the coast: - Landward, they are drilled trough permeable strata of white and grey chalk. - Seaward, mainly through relatively impermeable chalk marl, but with the presence of water in faulted zones, or in grey chalk.

Jan 1, 1989

Water conservation and compliance strategy can be cause for success or failure of a new or existing mining operation. Water accounting at outset, and pit and waste dump planning, may not fully consider total inflows, or sediment loads encountered during mine life. Environmental impact assessments, and permitting often dictates the rules, and these may change, to be more stringent, during course of mine development. This paper will identify techniques to control unprojected fresh water, or increased surface water flows in surface mine operations.

Feb 23, 2014