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By Florence Munter

This paper provides a discussion of the various federal and state laws governing water quality as related to mining operations. The specific laws addressed are the Clean Water Act, and the Arizona Mined Land Reclamation Act. Topics that will be addressed are mine water and process water discharges, storm water discharges, pollution prevention, dredge and fill, spill prevention control and countermeasure plan, and surface water protection. Proposed changes to the laws and regulations will be discussed. Compliance strategies will be suggested to prevent potential noncompliance and enforcement.

Jan 1, 1996

By G. M. L. Robinson

The Clean Water Act, as administered by the Environmental Protection Agency, has mandated industry, government and the public to comply with potentially conflicting and vague water quality statutes, regulations and guidelines. Universal regulatory strategies have been developed which have introduced and have created regulatory, compliance and institutional conflicts. Conflicts have been created because National water quality performance goals and design standards are vague, and, in many cases, cannot be scientifically justified. Because of regulatory technical requirements to define background and environmentally impacted water quality characteristics, the ability to achieve regulatory compliance is difficult. Difficult issues requiring resolutions includes but are not limited to site specific surface and ground water quality classification systems, water quality standards and guidelines, point and non point pollution sources etc. Because of these statutory and regulatory complexities, a confrontational regulatory system has been created as it relates to: - defining performance criteria in relation to design criteria; - resolving water quality statistical compliance conflicts; - defining laboratory precision requirements; - determining background groundwater characteristics; and - locating a representative point of compliance. Because of these complex regulatory issues, the ability to balance goals, needs and economics has not been achieved or in many cases has not been attempted, without legal intervention. A few examples illustrating where water and waste management compliance conflicts have been experienced.

Jan 1, 1992

By E. F. Jr. Young, H. E. Steinman, G. C. Smith

Through a progressive laboratory and pilot-plant program Jones & Laughlin Steel Corp has analyzed and corrected mine drainage pollution problems at all of its coal mines. In conducting this program, the company found no "typical" drainage discharge. Each discharge point at each mine was unique, so that varied approaches were needed to eliminate stream pollution. To illustrate the variety of these approaches, the treatment of drainage from foul, discharge points at three mines in Pennsylvania will be considered here. The flows and critical analyses of the drainage sources and treated effluents arc shown in Table I. Hydrated Lime Works at Thompson Borehole The discharge stream from the Thompson bore- hole at the Vesta No. 5 mine flowed into a small branch creek where it created a "yellowboy" deposit and affected aquatic life. Investigation indicated that hydrated lime would neutralize the acid and precipitate ferric iron without aeration. Treatment of the 150.000-gpd flow, however, created about 4000 gpd of wet sludge for which there was no nearby accumulation site. With State approval, this sludge was deposited through an unused borehole into an abandoned section of the Vesta No. 6 mine several miles away.

Jan 1, 1970

By J Seppelt, B Akerstrom, J Bubnich, D Seaman, T Waters

The Cadia Hill concentrator at Newcrest’s Cadia Operations has undergone several modifications and upgrades to treat an increased throughput rate of harder ore from the Cadia East block cave mine.Subsequent to the commissioning of the expanded circuit, the flotation cleaner block has undergone a systematic optimisation programme tackling all facets of circuit operation. This included debottlenecking circuit constraints and installation of Jameson cell technology to enhance copper and gold recovery while rejecting fluorine and gangue from the concentrate.This paper outlines the improvements over the course of the project and results obtained from the implemented actions.CITATION:Akerstrom, B, Seppelt, J, Waters, T, Bubnich, J and Seaman, D, 2018. Cleaner circuit optimisation at Cadia Operations, in Proceedings 14th AusIMM Mill Operators' Conference 2018, pp 457–476 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 29, 2018

By B. P. Baruah

A good deposit of high sulphur coals of tertiary origin is existent in North eastern region of India. These coals are known to have indifferent characteristics in comparison to other Indian coals. The general Physico-chemical characteristics are low ash and high volatile matter, calorific value and sulphur content. Sulphur in these coals (70-95% of organic) is mostly affixed to the structure of the coal. Owing to the stringent environmental regulations, the utilization of these coals has severe limitations due to high sulphur content. In the present investigation, sulphur incorporation in to these coals has been discussed along with possible organic sulphur functionalities. The various desulphurization techniques carried out for removing sulphur from these coals have been discussed. Two step oxidative desulphurization processes has been found to be most efficient for organic sulphur removal along with mineral matter and potential toxic elements. Keywords: oxidative desulfurization, potential toxic elements, sulfur incorporation

Sep 1, 2012

By Renee Y. Allee

The Chino open pit mine, concentrator, and smelter are located in Grant county in Southwestern New Mexico. Chino Mines Company is a partnership, two- thirds owned and operated by Kennecott Santa Fe Corp., and one third owned by MC Minerals Corp. (Mitsubishi) of Japan. The concentrator, with a design capacity of 37,000 tons of copper-molybdenite ore per day, was commissioned in July, 1982. Further design modifications have resulted in an increase in throughput capacity to 42,000 tpd

Jan 1, 1986

By Euclid P. Worden

In 1977, an article in World Mining1 reported a total of 2726 rotary blasthole drills in service. This figure included only those machines produced by three of the manufacturers building drills of this type. The total, therefore, is much higher. Rotary drilling in the mining industry is big business to the manufacturers and suppliers involved, and a significant cost item to mine operators. The time has come to take a hard look at rotary drilling technology with an eye to reducing costs by increasing drilling efficiency. The efficiency of any rotary drilling operation is best measured in terms of the rate of penetration achieved by the bit. In blast hole drilling, there are five factors which affect the rate of penetration. They are: (1) bit selection, (2) weight on the bit, (3) rotary speed, (4) hole cleaning, and (5) formation properties. Of these factors, all but one may be controlled by the operator. Looking at any one in detail may reveal possible improvements in the system. One of these factors -- proper hole cleaning - will be discussed in this paper. In order for a bit to perform at its maximum capability, each tooth or insert should strike fresh clean rock as it falls into its drilling position. If the tooth or insert lands on previously drilled cuttings, a major portion of the energy delivered to the bit is absorbed in redrilling this broken material. A major portion of the interest, therefore, should be directed to the proper cleaning of the bottom of the hole. In an in-depth study of the cleaning of large diameter holes, Allen2 reports that horizontal air velocities of 38.10 m/s are necessary to prevent the saltation of drilled cuttings on the bottom of the hole. The exact flow pattern on the bottom of the hole, however, is not generally known. The air leaves the bit through the jet nozzles and the mouths of the cones, but where it goes from there is uncertain. This problem should be investigated by the bit manufacturers because they can best utilize the results of such an investigation to provide a more effective product. Some work has been initiated in this area and competition will probably increase its intensity. Bailing velocity is the best criteria to measure the cleaning of the hole, including the bottom, and is the factor on which efforts toward improvement must be concentrated. The first consideration is "What should the bailing velocity really be?" In drilling deep holes for oil and gas, 15.24 m/s is the generally accepted figure. In blasthole drilling, the figures of 25.40 m/s for average rock to 35.56 m/s for iron ore were first mentioned by Capp3 in 1962. The recommendations are the same to this day. A number of questions could be asked in regard to the apparent disparity between these two sets of figures. Various investigators have derived formulas which support one or another of these criteria. A thesis on the subject was written by Alexander4 who derived a formula based on research which resulted in velocities in the lower end of the ranges quoted previously. He set out to compare this figure to laboratory tests and his tests indicated that the velocities given by the derived formula appeared to be high.1 Perhaps the best reason that the 25.40 to 35.56 m/s range has been used, is that these velocities seem to work. Below the accepted figures, low bit life and slow penetration rates occur. Above these figures, increasing amounts of abrasive wear on the drill pipe and stabilizers seem to appear. There is a fallacy to this entire approach, however. The entire velocity calculation is made using nominal bit and pipe sizes and compressor deliveries with no compensation made for losses in the system. Perhaps an examination of some of the things that are not presently considered could lead to some practical improvements in the operation.

Jan 1, 1980

By Euclid P. Worden

In 1977, an article in World Mining (1) reported a total of 2726 rotary blast hole drills in service. This figure included only those machines produced by three of the manufacturers building drills of this type. The total, therefore, is much higher: Rotary drilling in the mining industry is big business to the manufacturers and suppliers involved, and a significant cost item, to mine operators. The time has come to take a hard look at rotary drilling technology with an eye to re¬ducing costs by increasing drilling efficiency. The efficiency of any rotary drilling operation is measured in terms of the rate of penetration achieved by the bit. In blast hole drilling, five factors affect the rate of penetration. They are: 1. Bit selection 2. Weight on the bit 3. Rotary speed 4. Hole cleaning 5. Formation properties Of these factors, all but one may be control¬led by the operator. Looking at any one in detail may reveal possible improvements in the system. Cleaning the hole is a good place to start. In order for a bit to perform at its maximum capability, each tooth or insert should strike fresh, clean rock as it falls into its drilling position. If the tooth or insert lands on previously drilled cuttings, a major portion of the energy delivered to the bit is absorbed in re drilling this broken material. A major portion of the interest, therefore, should be directed to the proper cleaning of the bottom of the hole.

Jan 1, 1979

By S Sandover, D Glenister

Alcoa World Alumina Australia is committed to sustainability principles as a basis of business success into the future. In March 2001, Alcoa Inc chairman Alain Belda announced a set of far-reaching environmental goals for the corporation, with the challenge that they should be achieved in ways that enhance economic and social performance, while substantially reducing environmental impact. Application of Cleaner Production methods is seen as the key to achieving these joint objectives. In Australia Alcoa has launched a co-ordinated effort to accelerate our application of Cleaner Production principles to delivering cost-effective in-process solutions to environmental issues. Our Western Australian Operations are a signatory to the WA Cleaner Production Statement, through which we provide a Cleaner Production Plan to the State Government on a voluntary basis. This paper describes in general terms AlcoaÆs goals, achievements and directions in applying Cleaner Production to enhance business performance in the economic, environmental and social dimensions. Quantification of the benefits and tracking of progress in quantitative terms is a key challenge for the future

Jan 1, 2002

By A. K. Fallaw, G. Wang, L. R. Moore, S. Dobson, Y. Xiong, J. Gu

"As ores degrade, mining techniques and chemistries change to meet market demand and maintain product quality. The balance of recovery and grade is a significant challenge in the Crago Process where an anionic collector is used to float phosphate, followed by acid scrubbing, then an amine float to improve product grade. As the grade is a requirement for DAP and MAP production, recovery is the criteria to suffer. Phosphate losses in the amine float can bring overall recovery down by as much as 18%, creating a growing need to think outside the box to improve recovery. This paper will focus on the theory of amine tail recycling and the best methods to optimize the overall phosphate recovery by recycling the tails from the cleaner flotation step. INTRODUCTION In 2014 the total US phosphate production was down 13% over the prior year, from 31.9 to 27.1 Mt, which accounts for 12.32% of the world’s phosphate rock production. Florida and North Carolina phosphate production accounted for 80% of total US phosphate production, which was down from 85% the previous year. This decline is due in part to the closing of the last phosphate mine in Polk County, FL - which had an operating phosphate mine for over 100 years (Gurr, 2015). Another factor contributing to the reduction in contribution from FL & NC is the increasing challenges in beneficiating the remaining ore deposits. The Central Florida mining district has historically been in the Bone Valley deposit, where raw apatite was abundant with P2O5 values as high as 15%. The Bone Valley ore also had characteristics favorable to beneficiation to 27.5-29.7 %P2O5 while achieving recoveries above 86%. The move southward into the Hawthorne Formation has seen the ore feed grade hit some historic lows, and the matrix characteristics pose more challenges to phosphate producers. The Hawthorne Formation experienced lateritic weathering after the Bone Valley formation which altered the apatite to aluminum phosphate minerals, and alteration of montmorillonite to kaolinite, releasing MgO that caused the dolomitization of the top of the Hawthorne limestone (Cathcart, 1966). Elevated levels of dolomite can yield an increase in slurry viscosities, reduce production rates, and increase energy costs in the wet-acid fertilizer process. The MgO will also act to dilute grade, making it more difficult to achieve a standard 18-46-0 product (McHardy, 1981)."

Jan 1, 2016

By D. R. Mitchell

This paper discusses some of the fundamental physical and chemical characteristics of coal in Illinois that affect its preparation for the market. At the present time preparation consists almost entirely of sizing and hand-picking. The washing of coal has almost entirely disappeared from the state. This is a rather startling fact when one considers that in the year 1908 Illinois outranked all other states in the quantity of coal washed and a few years later, in 1912, 85 washing plants were reported. Two reasons are apparent for this change. One, which is probably the most important, is that immense areas of comparatively clean coal were opened; the other is that many of the early washing plants were inefficient, so that washed coal was looked upon with disfavor in many trade centers. Objectives of Operators Some of the outstanding preparation aims being given due consideration by operating men are: 1. The greatest possible production of lump and domestic sizes which bring in the market at least $1 per ton more than the fine sizes or screenings. 2. Efficient screen sizing with as little breakage as is consistent with economical operation. 3. The removal of extraneous ash and sulfur. 4. Utilization of low-priced screenings. 5. Suppression of dust in domestic coal shipments. Preparation Underground To get the greatest possible production of the larger sizes, preparation must start at the face. Improvements in blasting and loading have increased the sizes larger than 2 in. by as much as 20 per cent. at some mines. Tiffany and McKitterickl report the results of an investigation they made at a mine in southern Illinois in which, by a carefully controlled

Jan 1, 1931

By Ray W. Arms

The combination wet and dry coal-cleaning process is not an attempt at a compromise between the wets and the drys nor is its merit confined entirely to the limitation of moisture in the smaller sizes. It is more correctly, and more broadly, an application of the sized-coal cleaning principle adapting itself in an ideal fashion to present day multiple-size preparation practice. The purpose of this paper, therefore, is to call attention to the broader significance of the term "combination wet and dry process" and to mention some of the factors that govern its application. In the narrow sense, when considered apart from the sized-coal cleaning principle, the combination process finds its justification chiefly in the ability to limit the moisture in cleaned coal. Larger sizes of coal offer less superficial area compared with their bulk for the attraction of moisture films. They drain more readily in bins or railroad cars, having more interstitial space for the free flow of water. Therefore, they neither attract nor hold objectionable moisture percentages. In fact, there is so keen a demand for certain washed sizes containing some moisture that hygroscopic salts such as calcium chloride are applied to attract and retain it. When coal deliveries are made on a guaranteed moisture percentage the coarser sizes may be washed and mixed back with the fines without adding greatly to the original moisture but the fines must be dry cleaned or dried to control moisture. Thus in all respects moisture in the coarser sizes is less objectionable than in the fines. The implication of this statement, that moisture is always more or less objectionable, is true. It is safe to say that if dry-cleaning apparatus could be perfected to a point at which its technical results, cost and other aspects would be equal to wet washing, water would no longer be used. As it is, we find that good technical results are more difficult to obtain by dry cleaning than by water. Obviously the use of air tables for coarse coal is not ideal, for it involves the attempt to stratify material in a thin bed on a table surface when the load is only one particle deep. Furthermore, the various air cleaning tables on large sizes require a large volume of air for separation, more power to operate, more dust-collecting apparatus and involve more coal breakage.

Jan 1, 1931

By Kenelm C. Appleyard

In introducing to an American audience a description of the work done in dry coal separation in England and in Europe generally, it is perhaps desirable to give a short history of the development outside the United States of the particular processes with which the author is connected, and perhaps to stress a little the differences in the nature of the conditions to be faced. England actually presents one set of problems and the Continent of Europe another, since the character of the coals to be treated is entirely dissimilar, and the attitude of the coal industries towards coal preparation is also dissimilar. England for generations has been working by hand good seams of clean coal of the highest possible quality and has not felt any pressing need to clean its coal. Most Continental countries, however, especially in Central and Western Europe, have been working friable and often very dirty coals for so long that a washery is accepted as a part of the normal equipment of a colliery, with the result that the art of wet washing has reached a high state of perfection, particularly in Belgium and Germany. The advent of machine mining has intensified the problems to be faced in all countries, and in England has been coupled with the working out of the best seams in the older coal fields, thus bringing about the necessity of working thinner and dirtier seams with resultant difficulties as regards marketing the products, while Poland, with clean and well prepared coal, has in recent years been attacking established British markets in Scandinavia. In recent years, therefore, interest in coal preparation has been steadily gaining ground in England, although it has not yet reached Continental dimensions. Broadly speaking, the differences in preparation problems between England and the Continent boil themselves down to one of size. In England, for example, with the exception of the Kent coal field, the proportion of coal of a size less than ? in. to the coal less than 2 in. is very much less than on the Continent, and since the principal difficulties in dry cleaning lie in the fines it is easier to produce good figures on

Jan 1, 1931

By Charles H. J. Patterson

When coal is deposited on the decks of pneumatic tables, all fine particles clinging to the larger pieces are blown free by the air. Inasmuch as the air retains an appreciable residual velocity after passing through the bed of coal, it is capable of suspending particles of goodly size. This velocity is dissipated gradually and, unless confined, can readily extend beyond the limits of the plant. Today the ideal in the design and operation of pneumatic cleaning plants is not that they be no dustier than the ordinary tipple, but rather that they be as clean as an office or shop. This degree of perfection may not yet have been attained in any commercial plant, but it is not impossible of achievement. Not until recently has the recirculation principle been applied to pneumatic separating plants. In the writer's estimation, it has not yet been proved entirely satisfactory in commercial installations. A serious obstacle lies in the fact that it is practically impossible to provide a truly closed circuit. The air circuits must be interrupted at certain points, if only for the introduction of raw material and for the recovery of the finished product. It is feasible to prevent the escape of polluted air at these points, but this can scarcely be accomplished without admitting additional air into the circuit. These additions of air are cumulative, which necessitates means for emitting to the atmosphere the excess while still carrying its objectionable burden, if provisions are not made for conditioning. If it must be provided at all, conditioning is frequently simpler and more economical if applied to the entire volume of air involved. This procedure eliminates the extra initial cost and operating expense of the closed system. Crane Cheek Experiments The first noteworthy commercial installation of pneumatic equipment was made in 1922, at the Crane Creek plant of the American Coal Co. of Allegheny County, at McComas, W. Va. Six tables for cleaning coal between the limits of and 3 in. comprised the initial installation. Dust was collected by hoods connected by a system of ducts to exhauster fans. In this installation the unit dust burden was small, owing to the removal of fines from the feed by vibrating screens.

Jan 1, 1931

By S. M. Parmley

Experience has shown that there are some factors connected with the drying of fine washed coal that are not present in drying of slack coal as normally practiced at cement kilns or pulverized coal plants. It is the purpose of this paper to show some of these variations as they have been encountered under actual operation. The Champion No. 1 cleaning plant of the Pittsburgh Coal Co. uses the wet system of cleaning coal. The plant is equipped to produce commercial sizes or mixtures, the primary sizes being plus 6 in. and 4 by 6 in., which are hand-picked. Minus 4-in. sizes are all cleaned by the wet process. To produce a commercial product as free of moisture as possible, the washed coal is first passed over sizing and dewatering screens, then each size except the — ?-in. coal is conveyed to loading booms by slow-moving draining conveyors. As the +?-in. sizes are not heat-dried, no data will be given, as it is the purpose of this paper to describe the heat drying of — ?-in. coal as practiced at the Champion No. 1 plant of the Pittsburgh Coal Company. To fully appreciate the conditions, it must be remembered that the — ?-in. product is now shipped at a lower moisture content than when received from the mine. The incoming coal in the — ?-in. size will average 5 per cent. moisture and the shipped product 3 per cent. moisture. This is a case where a wet process gives a reduction of both ash and moisture in the fine sizes. The shipped product, therefore, is more uniform in all characteristics, and uniformity of product is the most important single factor in coal preparation. The 0 by ?-in. coal is first dewatered on slow-moving continuous bucket dewatering elevators, running at the rate of 40 ft. per minute, with 48-in. perforated buckets with ¼ by 1½-in. slots, spaced ? by 2?-in. centers staggered. The moisture in the coal discharged from the elevators runs 20 to 28 per cent., depending on the fineness of the product. The discharge from the dewatering elevator is further drained on a drag-type conveyor equipped with ½-mm. wedge wire screen. The conveyor discharges coal with an 18 to 25 per cent. moisture to three centrifugal dryers of the Carpenter type. The Carpenter dryers

Jan 1, 1931

By Joseph Alexis

Humphreys Engineering Co. has been associated with mining and milling since the turn of the century, but its greatest contribution to the industry was development of the Humphreys spiral concentrator in 1943. Few devices in the history of mineral beneficiation have been so uncomplicated. The spiral concentrator has no moving parts and requires no power except that needed to deliver slurry to the feed box, a requirement common to all concentrating devices. Although Humphreys Engineering Co. produces several models of spiral concentrators, the one -commonly used for coal cleaning is Model 24C-6 which has a flatter pitch than most other models. The spiral concentrator consists of a spiral conduit with a modified semicircular cross section. A slurry containing 20-35% solids by weight is fed to the feed box at the top of the spiral and flows downward. The heavier refuse particles concentrate along the inner side of the slurry stream and the lighter coal moves to the outside. The coal spiral has six complete turns-each turn consists of three 120°-sections and each section has a refuse port at the lowest point of the channel. The Humphreys spiral concentrator separates minerals in accordance with their physical properties (primarily specific gravity and particle shape). Aside from pumping slurry to the distributor, no energy is required to produce clean coal since the separating action is controlled by gravity. As slurry flows down the spiral channel, each particle is subjected to a centrifugal force, tangential to the channel. This force piles slurry on the outer rim of the spiral until the flowing stream reaches an equilibrium between outward centrifugal force and downward gravitational force. Once established, the stream position is relatively constant. In any flowing stream, differential velocities are present within that stream (the slowest fluid levels nearest the channel surface and the fastest layers at the center). As the channel curves, the lower slurry levels, retarded by friction, have much less centrifugal force and tend to move sideways toward the inner radius of the channel. As the bottom layers move inward along the bottom of the channel, the upper layers must move outward to maintain equilibrium. This cross sectional rotation separates the minerals and moves those of highest specific gravity toward the inner radius where they drop through refuse ports (see figure on following page). The simplicity of the spiral concentrator is apparent in operation. After tonnage, slurry volume, and percent solids of the feed have been determined-generally with laboratory testing-the operator's main concern is simple adjustment of the splitters located in the refuse ports. These splitters control the amount of refuse collected and, generally, once properly set they need little attention unless grade conditions drastically change or trash builds up and hinders laminar flow. Spiral concentrators are not overly sensitive to changes in pulp densities, variances in grade, or parti¬cle size and shapes. All these conditions may fluctuate over fairly wide ranges without adversely affecting recovery and product grade. In certain applications, desliming may improve recovery.

Jan 8, 1980

By A. C. Dittrick

THE Simon-Carves washer, originally known as the Baum jig washer, was first built in Europe about 1892. It was probably the first washer to use intermittent pressure of air on water in one part of the wash box to obtain water pulsations in another part. This type of washer was also the first to successfully clean various sizes in the same unit. Previous practice was to size closely before washing. Today there are several large firms abroad, and a few in the United States, that are constructing the Baum type washer. The design of all is practically the same, their differences being only in details. In 1928, the Hanna Coal Co. first gave consideration to the question of coal cleaning. It was believed at that time that by efficient removal of so-called noncombustibles appearing in the Pittsburgh No. 8 seam, certain markets that had been lost due to poor preparation might be recovered. Mechanical cleaning and mechanical loading were under consideration. This type of cleaning was considered the most practical means of removing impurities in the sizes below 4 in. It was decided to adopt mechanical cleaning and develop a system of mechanical loading that would be successful on No. 8 coal.

Jan 1, 1935

By A. McMullen

"IntroductionTHE LOW-VOLATILE bituminous coals of the Brazeau field, Nordegg, Alberta, are soft and weak in structure. The seams contain .bands of inferior material, locally designated 'black jack', and thin bands of friable carbonaceous shale having no definite horizon but usually 'floating' in the seam. Because of the weakness• of the coal and the friable nature of the shale bands, run-of-mine coal usually contains a very high percentage of fines, as •Shown in the following table:SIZE WEIGHT. %Plus 1/2 in 25.61/2 – 1/4 in 13.31/4 - 1/8 in 14.6Minus 1/8 in 46.5The most convenient way of cleaning the fine coal would be by treating it in association with the coarse coal, so that no additional plant would be necessary. To a limited extent this is possible in certain types of equipment, notably the jig. A system of washing without pre-sizing is not •attractive, however, when dealing with the friable coal under consideration, which contains •a preponderant proportion of fines. At the new Brazeau washery, separation is made at 3/8-inch on •a Robins 'Vibrex' •screen, the coarse sizes being cleaned in •a standard pulsator-type jig. A feldspar jig is used to clean the minus 3/8-inch fraction."

Jan 1, 1954

By J. Visman

The water cyclone washer has a number of advantages that makes it a desirable machine for the cleaning of fine-grained and friable materials such as 1,4 x 0" slack coals. In this paper results are presented of tests carried out on a shaly coal containing a high percentage of inter-grown materials from the Minto area, New Brunswick. The tests were con-ducted in the pilot plant of the Western Regional Laboratory in Edmonton. The test results show that the cleaning characteristics of this coal can be improved by lightly grinding the recirculating middlings fraction, which constitutes approximately 30 per cent (1.45-2.00 fraction) of the raw feed. • The cleaning of 1;4 x 0" fines by water cyclones compares favourably with other coal cleaning machines and has an added advantage of being extremely simple to operate, low in capital and operating cost, and high in capacity. The application of water cy-clones dates back approximately ten years, following its development at the Dutch State Mines. ( 3) A number of papers published d

Jan 1, 1961

By J. Yianatos

The cleaning circuit operation and its effect on the plant metallurgical performance, was characterized at Los Pelambres concentrator, Chile. Experimental data from columns, scavenger and regrinding stages was evaluated. Each stage was characterized by size fractions, and the interaction between stages (columns, scavenger, regrinding) as well as the effect that circulating loads had. The approach for describing the flotation equipment operation (cells and columns) considered the collection and froth zones separately. This methodology allows for the identification of the impact that particle size distribution has on the actual collection and froth transport processes, independently. In this way the effect of regrinding on flotation recovery and grade can be related to the corresponding operating variables, e.g. pulp flowrate, air flowrate, pulp level and pulp density, among others. The effect of gangue entrainment was considered using an empirical dimensionless correlation. The interaction between the circulating load and the overall performance of cleaning circuit was evaluated. The circulating load was defined as the ratio between the solid flowrate of scavenger concentrate over rougher concentrate. It was found that the overall cleaning flotation circuit (column-scavenger) can operate at a relatively high and constant recovery for a wide range of mineral treatment. This is possible when the scavenger has the capacity for compensating the decrease in column recovery at larger circulating loads. Under the condition of high overall cleaning recovery, the rougher stage closely represents the plant recovery. However, at large mineral treatment conditions, the design characteristics (e.g. concentrate transport channel capacity and transfer boxes) as well as instrumentation, control facilities and operation, became bottle-necked. A simulator was developed using empirical models for each stage (column, scavenger and regrinding) in order to evaluate proper operational strategies for cleaning flotation circuits Keywords: flotation, cleaning, regrinding, Vertimill, simulation.

Sep 1, 2012