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By G. J. Trezek

The use of polysilicates for treating heavy metals in soils and mining sludges is discussed. Results of the treatment are given for soil contaminated in a metal scrap yard operation and for copper mining processing sludges. The types of metals of concern are arsenic, lead, copper, nickel, cadmium, and zinc. The application of the treatment is predicated on the mixture and relative concentrations of the metals as well as the material matrix. Reductions in soluble concentrations (STLC or TCLP) of one to two orders of magnitude can be achieved with relatively small additions of silicates and cementitious materials.

Jan 1, 1992

By Robert R. French

Commercial grade gypsum beds up to 16 feet thick is present in southwestern Indiana. The major deposits are found at a depth of 350 feet to more than 500 feet below the surface. The ore body averages about 75 to 95 percent gypsum. Two companies are currently exploiting a deposit which underlies an area of several square miles near Shoals, in Martin County. Another deposit has been located in southwestern Owen County but has not been developed. The Indiana Geological Survey is currently drilling in Greene County and is considering further exploratory work in Perry end Dubois Counties.

Jan 1, 1965

By F. Villanueva Araya

Compania Minera Disputada de las Condes (CMD), an Exxon Affiliate stewarded by Exxon Coal and Minerals Company, operates two' copper mines and concentrators in Chile. Pilot plant studies were initiated in 1984 using a 0.46 meter and a 0.91 meter diameter column for the cleaning of copper concentrate. This eventually resulted in the design and operation of a rectangular column with an area of 6.8 m2, increasing the final copper concentrate grade from about 30% to almost 32'1. Cu without any loss in copper recovery. Evaluation studies of a commercial bubble generator as against the previously used filter cloth air sparger are now in progress.

Jan 1, 1990

By A. Bhagwat, S. Tadolini

"Steel members of the ground support systems in underground mines are routinely exposed to corrosive environment that may range from acidic to alkaline. Corrosion of steel bolts leads to metal loss and thereby, reduction in strength and useful life. Protective coatings are commonly applied to the steel bolts to combat corrosion. However, coatings are expensive and often cumbersome in practical applications. Instead, Minova has developed an innovative technology based on sacrificial anodes. The anodes were designed from non-ferritic alloys that are inferior to steel on the Galvanic Series. This paper will present data from field testing to show significant benefit of the technology. Potential applications in current products will be discussed. INTRODUCTION Corrosion is a physical alteration of a steel material from electrochemical reaction with its environment that often results in reduction of the mechanical and physical properties of that material. Mine roof bolts, the subject of this investigation, are particularly susceptible to corrosion as they can be exposed in their working environment to ground water and air with high humidity. As other researchers have determined, corrosion increases markedly in sulfide ore bodies due to acid runoff. There are several types of corrosion that a rock bolt is likely to undergo when used for ground reinforcement in underground mines (Aziz et al., 2013). Of all the types of corrosion, pitting is particularly dangerous as it can remove capacity for the bolt to deform with subsequent strata movements. Sudden failure of a bolt is likely to occur when severe pitting corrosion is experienced. The type and nature of corrosion depend on the nature of the ground condition and bolt encapsulation. Generally, the type of corrosion and severity of the corrosion varies along the axis of bolt. Almost all of the mine roof bolts used in mines, with the exception of fiber reinforced polymers, are made from steel. The corrosion of iron is an electrochemical phenomenon with the overall equation:"

Jan 1, 2018

By Jean E. Tilden

An investigation of several trace elements distributed among sulfide minerals from deposits located in the southeastern United States was conducted. The deposits investigated are distributed within both the Blue Ridge Province and the Piedmont Province, which are contiguous geographic provinces. Twenty five deposits were examined;' eleven in the Blue Ridge Province and fourteen in the Piedmont Province. Figure 1 shows the locations of deposits investigated. In the deposits investigated, the mineral phases examined were pyrite, pyrrhotite, chalcopyrite, and sphalerite. These phases were chosen because of their relatively widespread occurrence, although no pyrrhotite was seen in the Piedmont Province. A total of 116 polished surfaces of ores were prepared, and mineral phases were collected from these surfaces for analysis. Samples were analyzed for cobalt, nickel, manganese, lead, tin, chromium, molybdenum, and gold. A total of 372 analyses were made. Trace elements were determined by atomic absorption spectrophotometry following standard procedures. In this study, trace elements are defined as those elements which are present in the mineral but which do not affect the chemical formula for that mineral. Lead is considered as a trace element only in ores where little or no lead sulfide could be identified as a distinct mineral phase.

Jan 1, 1972

By J. E. Miller

The development of a new means of measuring the relative abrasivity of a slurry came about by necessity in 1967 during a full scale loop test of a 560 H.P. reciprocating pump handling magnetite slurry. In order to evaluate the life of expendable fluid end parts, the question of the amount of attrition in a re-circulated slurry had to be considered. An expected reduction in abrasivity as a result of this attrition would certainly give erroneous data on a parts life test. There- fore, some means of measuring such change in abrasivity became imperative. Several test methods were investigated1 but it was felt that these did not fully represent the wear due to back and forth rubbing action associated with a reciprocating pump. A "rubbing block" device used some years ago to determine the quality of hard facing materials was recalled, along with its shortcomings, in that an attempt was made to suspend a small percentage of abrasive particles in a colloidal viscous "mud". Erratic results were attributed to the fact that it was difficult to maintain a consistent slurry concentration under the metal wear block and the reciprocating speed was not great enough to maintain good agitation.

Jan 1, 1973

By William A. Rehrig

During recent years, there have been frequent investigations on the geochemistry of biotite. This work has emphasized, and no doubt was prompted by, factors related to mineral exploration, particularly for those deposits of the porphyry copper type. A large number of papers have been devoted to the obtainment of trace-element data from plutonic biotite. These data have been used to extract primary geochemical information pertaining to the parent magna and the hydro-thermal system which together give rise to porphyry copper deposits. In two early works, Putman and Burnham (1963) and Parry and Nackowski (1963) analyzed base metal contents of ferromagnesium minerals, primarily biotite, from various barrenfmineralized plutons of the Basin and Range Province. One similar conclusion from the two studies was that the Cu, Zn, and Pb contents of magmatic biotite served as indicators of ore development within the granitic rocks genetically related to ore. This theme was then pursued vigorously by a number of authors until the present time. Results, however, have been contradictory, as reviewed by Coope (1974). For example, studies by A1 Hashimi and Brownlow (1970), Lovering et a1 (1970), Putman (1972), and Graybeal (1973) continued to support positive primary relationships between the trace-metal content (usually copper) of biotite and associated sulfide mineralization. By studying biotite in close spatial association will sulfide occurrences, Putman (1972) and Graybeal (1973) developed models for base metal partitioning in magmatic systems based on their discovery of inversely distributed copper between silicate (biotite) and sulfide phases. Conversely, research by Bradshaw (1967) and Blaxland (1971) plus the recent findings of Parry and Jacobs (1975) and Kesler et a1 (1975) found little if any evidence to support a correlation of biotite base-metal or

Jan 1, 1976

By Peter F. Howard

The lower Middle Cambrian phosphorite deposits of the Georgina Basin shown in Figure 1 were found in the period 1966-1968 by three companies, namely, International Minerals and Chemical Corporation, Continental Oil Corporation and Broken Hill South Limited. Of these deposits the significant ones are Duchess, Sherrin Creek, D Tree, Lady Annie, Lady Jane, and Wonarah which together aggregate several billion tons reserves of phosphate. Due to the economic factors of freight costs to the coast and softening of the world market price for rock phosphate, none of them is in production, nor is any in the development stage. This paper reviews the historical background to the discovery of these deposits and then deals principally with the discovery of non-outcropping phosphorites in the Barkly Tablelands of Northern Territory by the interpretation of gamma radiation logs of abandoned water bores.

Jan 1, 1971

By A. S. Paschoa, A. W. Nóbrega

INTRODUCTION There are now over twenty years since the radiological characteristics of the brazilian regions of Araxá, Tapira and Barreiros, three locations adjacent to each other, in the state of Minas Gerais, Brazil, started being surveyed by investigators from the Instituto de Biofísica da Universidade Federal do Rio de Janeiro (IB/UFRJ), Pontifícia Universidade Católica do Rio de Janeiro (PUC/RJ), and New York University (NYU) (Roser and Cullen, 1958; Cullen et al, 1980). The importance of the Araxá apatite – Ca5,(P04)3(OH, F, Cl) - and pyrochlore - NaCaNB206F - for the production of large quantities of fertilizers and niobium was early recognized (Roser and Cullen, 1958). Interesting data have been gathered and published throughout the years on the contents of naturally occurring radionuclides in geologic materials, soils, grass, foods and waters of the Araxá region (Eisenbud, et al., 1964; Penna Franca, et al., 1965a, b; Roser et al., 1966; Penna Franca et al., 1970; Cullen, 1977; Penna Franca, 1977; Cullen and Paschoa, 1978; and Cullen et al., 1980). The radioactivity of the Araxá region is associated with mineral deposits of niobium rich pyrochlore and phosphate rich apatite. There are in this region mineral ores with 3 to 5% pyrochlore with 2 to 2.5% Th as Th02 and 50 to 150 ppm U308 in the matrix, while the apatite deposits contain up to 150 ppm U308 and a thorium concentration similar to that of the pyrochlore deposits (Paschoa and Palacios, 1981). As an indication of the high thorium content of the Araxá soils the 228Ra and 224Ra activity concentrations were reported to range from 10.6±0.2 to 62.4±0.7 pCi228Ra/g soil in 7 samples and 2.1±0.1 to 104±1 pCi224Ra/g soil in 19 samples (Cullen, et al., 1966). The uptake of radium isotopes by edible roots vegatables and fruits growing in the soils of the Araxá region can be illustrated by the data listed in Table I. The biological availability of natural radium isotopes in some segments of the Araxá soil allows a large variation in the 228Ra, 224Ra and 226Ra concentrations in vegetables and edible roots, as can be seen in Table I. This fact makes quite difficult a quantitative local assessment of the radiological implications of mining the Araxá mineral deposits of pyrochlore and apatite for production of niobium and phosphate fertilizers, respectively; since one cannot easily separate the naturally occurring from the technogically enhanced radionuclide contents of foods. The position of the city of Araxá inside the contour of the state of Minas Gerais appears in the upper part of Figure 1, which shows the outlined map of Brazil with the positions of the cities Brasilia and Rio de Janeiro also indicated. The lower part of Figure 1 is a representation of the Araxá region in an expanded scale, which indicates the locations of the pyrochlore and apatite deposits in relation to the city of Araxá, as well as the nearby hydrographic basins. The distance between the city of Araxá and the pyrochlore deposit is about 8 km, and between the pyrochlore and apatite deposits is 4 km. This paper deals tentatively with the radiological implications of the industrial operations taking place in the Araxá region for the exploration of the pyrochlore and apatite deposits. However, one must bear in mind, firstly, that the radiological implications of these industrial activities are by far too complex to be covered adequately by the limited amount of data to be presented in this paper, and secondly, that such implications cannot be considered of local character only. INDUSTRIAL OPERATIONS The commercial exploration of the Araxá deposits of pyrochlore and apatite started only few years ago, motivated by the increasing demand of niobium and phosphate fertilizers in Brazil and the world. As a consequence of the industrial operations in Araxá, a redistribution of the uranium, thorium, and radium originally present in the local deposits of pyrochlore and apatite started occurring in the seventies, with possible radiological implications for the Araxá region and its immediate surroundings, not to mention the destinations of the end products of such industrial operations. A literature review on the radioactivity associated with the extration industries of selected minerals was made by the USEPA (Bliss, 1978). The low level radioactive wastes of the industries for copper ore mining and rare metals processing have been object of particular attention (Fitzgerald, Jr., 1976; Eng, et al., 1979), but the short and long term implications of the radioactivity associated with the niobium industry were also subjects of concern (Knight and Makepeace, 1978). Recently, high 232Th and 226Ra concentrations in samples from the tin mining industry in West Malaysia were reported (Hu et al., 1981). A great deal of attention has been dedicated to the implications of the redistribution of radionuclides originally present in the mineral ores used by the phosphate fertilizer industry (Moore, 1967; Menzel, 1968; Spalding and Sackett, 1972; Eisenbud, 1973; Guimond and Windham, 1975; Guimond, 1976; Roessler,

Jan 1, 1981

By Barry Hunsaker

I cannot help but be reminded, as I stand here today, of my boyhood years and heritage, both of which are inextricably tied to this very valley and are, in a: bay, apropos of the theme of this Keynote Session. I remember the scarcity of people. For example, 48, 000 in Phoenix and 436, 000 in the State in 1930 and 65,000 in Phoenix and 499, 000 in the State in 1940. Today Phoenix boasts a population of over 500, 000 and the State a population of 1, 500,000. I remember the' lack of facilities, goods and services, including gas and electric power. I recall stories of my grandfather who had the freighting or teaming contract to haul all the supplies and generating equipment, by wagon mind you, up the old Apache Trail to Roosevelt Dam. . .a three day trip from the nearest railhead which, by the way, was not Phoenix, for it did not merit a railhead on those days, but the village of Maricopa approximately 25 miles south of Phoenix. I remember chopping firewood, heating wash water on an open fire in a No. 3 wash tub at the rear of the house and doing my school homework by the light of a kerosene lamp just 25 to 35 years ago within what is now a large metropolitan area

Jan 1, 1965

By S. Chander

The results of an investigation to characterize the chalcopyrite/solution interface are presented. Several techniques including galvanostatic and steady state polarization, cyclic voltammetry and impedance spectroscopy were used. The results show that the dissolution of chalcopyrite is incongruent. Initially, at low potentials(<O.34V), iron species are released which give rise to the growth of an iron-deficient sulfide (IDS) layer. The dissolved iron might reprecipitate as a hydroxide layer depending on solution composition. Continued oxidation involves diffusion of species through the product layer. At higher potentials (>O.48V) further oxidation leads to dissolution of copper and sulfur species with a resultant breakdown of the IDS layer. The changes in properties of surface coatings resulting from various electrochemical treatments are discussed.

Jan 1, 1991

By Omar A. Muhtadi

Brohm Mining Corporation, in conjunction with Geobiotics, Inc. has nearly completed a pilot heap biooxidation test on sulfidic ore from the Gilt Edge Mine near Rapid City, South Dakota. Some results from the pilot testing have shown the correlation between the extent of biooxidation and the increase in cyanide gold recovery seen in the laboratory. Bench scale testing showed approximately a 1: 1 correspondence between percent biooxidation and percentage increase in gold recovery. The economics of large scale biooxidation were also evaluated in terms of increased gold recovery versus the time and cost of biooxidation. In the pilot test, the rate of biooxidation became limited by the acid water neutralization system. Later in the test, measures were taken to overcome this problem. Results from bench scale column bioleach testing showed that the Gilt Edge sulfide ore is quite amenable to biooxidation with a substantial increase in gold recovery with just partial biooxidation. Direct cyanide gold recovery of 51 % on ore crushed to -3/8" was enhanced to 82-85% after oxidation of37% of the sulfide as measured by iron. Laboratory experiments also showed that the slow rate of biooxidation of this ore could be accelerated by removal of metal sulfate build up from the leach liquor. The combination of these normally non-toxic metals became inhibitory to biooxidation if not removed by the neutralization circuit.

Jan 1, 1995

By R. C. Milici

Historical production data and reserve decline rates can be used both to predict future coal production rates and to estimate when the reserve will be depleted. Reserve estimates inferred herein from historical production data and decline rates are commonly lower than estimates made from geologic data. The latter include significant amounts of lower quality (deeper, thinner, higher sulfur) coal which may be mined when the better deposits are depleted.

Jan 1, 1997

By S. Tuylu, D. Adiguzel, A. Bascetin, E. G. Savas, O. Ozdemir

"Paste Technology has some advantages comparing to other surface disposal methods. With this method, it is possible to pump high concentrated solid materials to very long distances without segregation problem. However, it is known from Literature that pumpability of materials is completely related to rheological properties of the materials. For this reason, in this study, the rheological parameters (e.g. yield stress and viscosity values) of the paste material prepared from Pb-Zn tailings at various solid ratios (60-85%) were obtained in order to determine the pumpability of the paste material. Additionally, slump tests, which are usually used in mining industry, was carried out. Finally, regression analysis was made between the slump values and rheological parameters of the paste material to find a correlation between two independent parameters. The results showed that there is a great correlation between the slump values and the yield stress of the material. On the other hand, there was no correlation with viscosity: ty=430.28-16.877Sv (R2= 0,94; ty: Yield Stress (Pa), Sv: Slump Value (cm)). Based on the results obtained from this study, it can be clearly concluded that the slump values obtained from a simple test can be used to predict yield stress values of paste materials. INTRODUCTION Recently, surface disposal of mining tailings has become one of the biggest problems in mining industry in terms of environmental issues. Therefore, several researches have been focused on this subject in order to find a best solution or method for this problem. These studies showed that paste technology has some advantages compared to other conventional methods. Tailings thickened to the extent show no segregation of particles during transportation, and relatively small amount of settling occur post-deposition which are often called “paste” (Cincilla et al. 1997). Paste tailing technology has two applications in the industrial area as underground paste fill and surface paste disposal. Paste tailing technology was first started to be used in Grund mine, Germany in the late 1970s (Grice, 1998). Process tailing material, water and - if needed - cement materials, which are the components of the paste, must be blended to obtain a homogenous mixture suitable for pumpability. Consistency behavior of the paste material is determined using a conventional sedimentation cone concrete test (slump). Meanwhile, the slump value of the paste must be between 200 and 250 mm for surface applications (Newman et al., 2001). Additionally, in the case of underground paste system, the optimum slump value must be between 150 and 200 mm. On the other hand, the water content and density of paste at certain slump value change depending on the amount of fine particles in the tailing sample. While moisture of the material will be high, its density will be low because of surface area of particles which increases with decrease in particle size (Meggyes and Debreczeni, 2006). For pumpability of the paste to long distances, slump value of the paste must be good enough to be accepted for use of surface paste disposal. Paste material has a yield stress because they show non-Newtonian behavior and generally is classified as a Bingham plastic fluid. (Cooke, 2008; Theriault, 2003). In addition, the appropriate viscosity value of the paste along with the yield stress must be between 100 and 250 Pa (Bascetin et al., 2013; Bascetin et al., 2014; Bascetin et al., 2015)."

Jan 1, 2016

By Ramazan Comakli, Cemal Balci, Nuh Bilgin, Hanifi Copur, Can Polat, Deniz Tumac

"Application of mechanical excavators for rock excavation in both civil construction and mining engineering fields has increased significantly in recent years. Prediction of the excavation performance of any mechanical excavators – tunnel boring machines, roadheaders, impact hammers, continuous miners and shearers for any geological formation is one of the main concerns in determining the economics of a mechanized mining and/or tunneling operation. A new portable linear rock cutting (PLCM) device was developed in the Mining Engineering Department of Istanbul Technical University and supported by The Scientific and Technological Research Council of Turkey (TUBITAK-112M859). The PLCM is used for cutting small core or block rock samples by a real-life mini disc cutter. The results from the PLCM are compared with the results obtained from the full scale rock cutting tests and theoretical model. It is found that there is reliable correlation between test results obtained from both cutting tests and theoretical model. 1. INTRODUCTION Mechanical excavators are currently the only alternatives to drill and blast due to higher production rate, increased safety, uniform muck size, less roof support, easier ventilation, continuous rather than cyclical operation, and possibilities for automatic control. The most of large civil tunneling and some mining projects are now carried out by mechanical excavators rather than drill and blast methods. Mechanical excavators can be categorized into two main groups: full-face and partial-face machines. Full-face machines such as tunnel boring machines excavate the face in one mode at the size of the cutterhead. Due to their cutting mode, the shape of the face profile by the full-face machines can only be circular. As for partial-face machines, the cutterhead is attached at the end of a boom. The face profile excavated by the partial-face machines can be from circular to horseshoe shape due to the cutting mode of the boom."

Jan 1, 2016

By S. P. Singh

Drifts are the nerve centre of underground mining. They provide essential communications between primary openings and production areas. In view of their strategic importance in the overall safety, economy and productivity of mines, an empirical approach for blast design during drifting has been proposed in this paper. The approach was developed with the objective of minimum blast damage and provides computerized blasthole patterns for drifting operations. The drift blasting practices and problems in Canadian mines have also been reviewed in this paper.

Jan 1, 1991

By R. M. Hernandez

The Bureau of Land Management (BLM) constructed four passive biochemical reactor systems (BCRs) to treat mining influenced water (MIW) in the Bunker Hill Superfund area near Coeur D?Alene, Idaho between 2002 and 2003. Initially, the BCRs operated very effectively. However, in the past couple of years, the zinc removal effectiveness of the four BLM BCRs has declined [1]. The central objective of this study was to characterize the microbial communities and substrate present within the BLM BCRs and to use these factors to propose strategies to promote sustained sulfate reduction levels. Microbial communities were characterized by quantifying total bacteria and sulfate reducing species. Substrate was characterized by quantifying the percent organic, acid soluble organic, acid insoluble organic, and bioavailable material within the BCR. The results suggest the depletion of bioavailable organic substrates is the primary cause of the decline in zinc removal and not the microbial community structure. The ability to assess the amount of bioavailable organic substrate and microbial community is important to the understanding of the sulfate reducing capacity of the BLM BCRs and developing strategies to facilitate performance enhancement of the current BLM BCRs. The characterization of organic substrate and microbial community structure are also important to improving design of future passive treatment systems for mining influenced waters.

Jan 1, 2010

By Norman F. Schulz

The Davis magnetic tube concentrator is a laboratory machine designed to separate a small sample of pulverized magnetic iron ore into magnetic and non-magnetic fractions. It was developed in 1921 by mechanization of a test previously performed manually. (1)(2)(3)(1) No significant changes have been made in the design of the apparatus since that time. The Davis magnetic tube test continues to serve as a practical basis for judging the amenability of an ore to magnetic separation and for controlling magnetic separation plant operations. The apparatus consists of an inclined cylindrical glass tube supported adjacent to closely spaced pointed poles of a powerful C-magnet. (Figure 1). To conduct a tube test, a sample of a suitably prepared ore is poured into the water-filled tube. With wash water flowing through, the tube is oscillated to gradually reject the weakly magnetic ore particles until the desired degree of separation is attained. Both the magnetic concentrate and the tailings may be recovered for examination.

Jan 1, 1963

By C. Newman

"Over the past decade, as conventional underground deposits have been depleted, mining operations have been forced to produce at greater depths and in more geologically and geometrically challenging conditions. As such, there has been a global increase in the application of cemented paste backfill (CPB) in tabular deposits utilizing open stope mining method with a delayed backfill placement. Despite the extensive use of CPB, many fundamental factors affecting the design of safe and economical fill structures are still not well understood. A critical issue in the design of backfilled stopes is the determination of stress states within the fill material itself as well as the surrounding rock mass. Analytical equations provide a means of quickly evaluating the effectiveness of a given design. However, in developing these equations large assumptions are implemented to simplify the design problem. It is important that one understands these simplifications as well as their effect on the overall design. This paper investigates common analytical equations utilized in the evaluation of single vertical backfilled stopes and their assumptions through comparisons to numerical modeling results. INTRODUCTION AND BACKGROUND As the mining industry continues to produce at greater depths and in more geometrically and geologically complex conditions, cemented paste backfill (CPB) has gained traction as a means of providing localized ground support in modern stope-and-fill mining operations. The application of CPB in stope-and-fill mining as a ground support material has led to the reduction of mine waste costs, while increasing both mine production and stability. In an attempt to achieve total extraction of the mining reserve, stope-and-fill mining operations often employ a primary-secondary excavation-support sequence (see Figure 1). In this practice, primary stopes are initially excavated and then backfilled in a two-stage pour; plug and final pours. During the first stage (plug), a CPB material with increased cementitious content is placed at the bottom of the stope providing a strong base from which to build a backfill structure as well as protect mine works from material breakthrough. Following placement, the backfill plug is allowed to cure to a given strength as designated by the mine design. Upon achieving the required cure strength, a less cementitious CPB material is used to backfill the remaining stope area. This is referred to as the final pour stage. With all primary stopes excavated and supported using backfill, the extraction of the secondary stopes commences as primary stopes are utilized as artificial pillars. While the application of CPB in a primary-secondary extraction-support mining sequence allows for a substantial increase in reserve recovery, it is imperative the mining personnel and planning engineers have a clear understanding of the material’s behavior and stress interaction with the surrounding rock mass to ensure the most efficient, cost-effective, and safe extraction of underground deposits."

Jan 1, 2018

By W. C. Hirt

Selective flocculation was used to produce superclean zinc concentrate with minimized silica contamination. Research was carried out on a flotation concentrate from the Jersey Miniere Zinc Company (JMZ) in Gordonsville, Tennessee. The material was first dispersed with sodium silicate and then causticized tapioca starch was used to selectively flocculate the sphalerite, leaving the silica in suspension. This technique has been applied commercially to iron ore beneficiation but has never been used for processing zinc. The feed material assayed 0.45% Si02. Use of 0.56 kg/tonne (1.13 lb/st) of sodium silicate and 0.070 kg/tonne (0.141 lb/st) of causticized tapioca starch resulted in 98.2% zinc recovery in a purified zinc concentrate assaying 66.0% Zn and 0.24% silica. The present target level for silica contamination in JMZ zinc concentrates is 0.3% Si02. This work has shown that selective flocculation offers a potential method for cleaning flotation concentrates, particularly where low silica products are required.

Jan 1, 1993