Search Documents

By G. G. Hatch

FOLLOWING World War II there was an urgent need for the development of domestic sources of ilmenite to take care of the expanding needs of the titanium dioxide pigment industry. In addition, there was the interest by the pigment manufucturers and others in titanium metal. Prior to the war the pigment industry in the United States had obtained its major tonnage of ilmenite, analyzing 55- ?60 per cent Ti02, from India. However, as a result of the shipping situation which developed during the war, the pigment manufacturers had to consider the use of lower grades of ilmenite located on this continent .and several companies undertook extensive exploration programmes to locate and develop such orebodies. Probably the most significant deposit that was found as a result of these ?programmes was the orebody .at Allard Lake, Quebec, owned by the Quebec Iron and Titanium Corporation. This ?Company was formed in 1948 by the Kennecott Copper Corporation and the New Jersey Zinc Company to mine this ilmenite ore and treat it in electric furnaces to produce titanium dioxide slag for the pigment industry and iron for the steel industry.

Jan 1, 1956

By J. C. Bothan

A program to provide technical in-formation on the use of fuels in pyro-metallurgical processes, from the Canadian fuel viewpoint, was initiated about five years ago by a Canadian Institute of Mining and Metallurgy liaison grou1> composed of members from the Coal Research Committee of the Coal Division and the Iron and Steel Committee of the Metallurgy Division. This paper is another of a series prepared for this program. Previous papers included a review of pyrometallurgical processes of Canadian interest, a survey of ferrous processes relevant to the development of an integrated steel industry in western Canada and a survey of the fuel requirements of the non-ferrous metals industry in Canada. It is widely recognized among per-sons familiar with the Canadian coal industry that, because of the large resources of coking coal in western Canada, the

Jan 1, 1963

By Flavio Rojos-Tapia, Oscar Pereira-Cerda, Samuel Sánchez-Pino, Samuel Sánchez-Baquedano

"Pneumatic flotation was introduced to the Chilean Copper Mining Industry in 1993 by Ingeniería de Minerales S.A. (IDM). The technology is based on the designs of Dr. Rainer Imhof from Germany, who is the designer of several different types of pneumatic flotation cells, already sold through his Company Maelgwyn Mineral Service Limited (MMH). The company is represented by Ingenieria de Minerales S.A. (IDM) in South America.Pneumatic flotation, has been used in tough industrial applications .It has been successfully used for metallic ores such as copper sulphide and oxide minerals, copper slag, silica and silicates from iron magnetic preconcentrate (reverse flotation) and gold. It has also provided promising results when applied to molybdenum flotation. The latest applications, with ultrafine molybdenum particles in operating plants, is showing the V and G Cell (end model designed) as a real technological alternative to conventional flotation., The G Cell is an extremely high speed flotation machine with high selectivity which introduces the possibility of producing a final molybdenum concentrate with only one stage of cleaning. This is a completely new development in molybdenum flotation in the industrial circuit which has the potential to dramatically reduce the circulating load in the cleaning circuit. As a consequence the capital costs of future Molybdenum plants may also be reduced. The suitability of the G Cell will have to be determined on a case by case basis but it provides the metallurgist with an alternate flowsheet for consideration.The good performance of the G Cell can be explained by the high gas hold-up and very effective micro-turbulence which helps improve the attachment of solid particles to the bubbles. This technology may change our traditional concept of residence time in flotation. Additionally, the rotation phenomena introduced in the vessel of the G Cell ,creates radial separation forces which are critical to achieving a more rapid separation of the target minerals from the tailing. This results in a much reduced residence time requirement in the flotation machine. Some benefits associated with the use of the new G Cell are: less energy consumption, less maintenance costs, simple and reliable circuit to operate and a small area required for installing the circuits.As a result of the industrial experience in the Chile, the pneumatic flotation type G Cell can be regarded as a technology which must be considered as a replacement technology for the rougher and cleaner stages for fine particle flotation."

Jan 1, 2008

By N. S. Spence

INTRODUCTION WHILE TITANIUM, the element, has been known for over 150 years, titanium, the metal, is a relative newcomer to the metallurgical and industrial scene. The reasons for this chiefly lie in the refract1Hy nature of titanium compounds; the high melting point of the metal; the great activity of elemental titanium, particularly at temperatures close to .and above the melting point; and the pronounced deleterious influence of certain impurities on its mechanical proper-ties. Early efforts at production of the metal were, consequently, either unsuccessful or resulted in products having sub-metallic properties. With the considerable improvement in equipment, materials, and skills that have developed within the past twenty-five years, later investigators have had a better opportunity to overcome some of the inherent practical obstacles and to come to grips with the essential technical problems. NATURAL ABUNDANCE OF TITANIUM Titanium is one of the most abundant metallic elements. It has been estimated (1) that titanium comp-rises about 0.65 per cent of the earth's crust, and therefore ranks fourth among the structurally useful metals in the order: aluminum, iron, magnesium, titanium. It must be appreciated that the relative abundance of the element is only a crude indication of its potential availability, since a very substantial proportion is present as a minor constituent in practically all igneous rocks. By comparison, present-day ores of titanium are relatively few and are but a minor fraction of the estimated total titanium contained in the earth' s crust.

Jan 1, 1951

By A. G. Roach

Introduction This paper deals with the operations and plant of the Craigmont Corundum Project, formerly of Wartime Metals Corporation but now under the Mines Section of the Resources Development Branch of the Department of Reconstruction and Supply. Corundum is recovered by the re-treatment of an old tailing deposit at Craigmont, Ontario. Crude concentrates so produced are shipped to the plant of the American Abrasives Company, Inc., at Westfield, Mass., for final processing and distribution to the abrasive industry. The plant was recently described in a paper entitled Craigmont Corundum which was presented by the writer before the Chicago meeting of the A.I .M.E. in February, 1946. General The Project is located on? lots 4 and 5, concession XVIII, township of Raglan, Renfrew county, Ontario, near the village of Combermere, which is on Highway 62. The property is about 135 miles from Ottawa. The general area enjoys a pleasant climate with moderate summer temperatures, though the winters are rather severe, the mercury frequently falling to - 35 deg. F. The excellent boating, fishing, and hunting have made the district a favourite resort for tourists. Lumbering is the main industry. Some farming is carried on, but the soil is poor and much of the land is hilly and rocky. There are no other operating mines in the immediate vicinity, though several 'industrial minerals', including mica, feldspar, nepheline, beryl, socialite, and others have been produced in the area. The district is drained by the York and Madawaska rivers and is generously dotted with large and small lakes. The general elevation is about 1,000 feet above sea level, though numerous hills rising several hundred feet give a rolling appearance to the landscape.

Jan 1, 1946

By A. M. Childs, R. F. Mather, K. R. Rawling

"The challenges encountered in the design and construction of mines and their process facilities today are becoming more intense and the engineering more competitive. The need to incorporate new techno1ogy to compensate for ever rising costs is always present, but its application in the harsh environment of Northern Canada increasingly requires the inclusion of new proven methods and innovative approaches to arrive at economically attractive projects.This paper deals with the development of the process design for the Cullaton Lake Gold Mine in the Northwest Territories. Particular emphasis is given to the interaction of the imposed construction and testwork schedules, and their effect on certain process decisions.The challenge that faced the project team may be defined by the following factors:1. A schedule which required that metallurgical testing, engineering, and procurement and delivery of all equipment and construction supplies should be complete within a period of ten months.2. Transportation of all personnel, equipment and supplies to the site by airlift, as no road was available or affordable.3. A six week period when transportation to the site was impossible.4. The extremes of temperature beyond the tree line in the Northwest Territories.5. A complete lack of infrastructure in the area."

Jan 1, 1983

By J. Chelsey Dawson

In presenting a thesis on this subject it is advisable to explain a few of the reasons for its seeming incompleteness. World progress has brought us to a position where approximations are not only to be condoned, but regarded as absolute essentials. Production in anticipation of demand is always accompanied by mistakes on the part of the producers. Only through trial and sometimes erring hypotheses may there be evolved the true course and theory upon which the steady triumphant march of world-wide industry depends. The average person likes to have everything placed ?before him in a clear and convincing manner. It is the impossibility of doing this which, in many cases, arises to confound the writer on shales. All that one can do is to present, as lucidly as possible, the known hypotheses' and theories on the subject and leave the reader to study and work out the truth for himself. Many theories have been advanced on the origin of oil-shales ; some may be correct in certain instances and not in others; however, the writer will attempt no decision as to which are and which are not correct, but .will merely point out the relative merits of each. The figures given for reserves of oil and shale in different countries are only approximations and give but a rough idea of the true conditions.

Jan 1, 1925

By Jean M. Richardson, Steven R. Williams

"Geometallurgical mapping is a new team-based approach that documents variability within an orebody and quantifies the impact of geology (host rocks, alteration and structure) and mineralogy on grinding, metallurgical response and metal recovery processes. The quantitative, spatially constrained database that results can be readily integrated into 3-D block models and mine planning activities. Thus it is an important tool to reduce the technical risk associated with new mine developments or expansions.Normally undertaken during pre-feasibility or feasibility planning stages, the first step of geometallurgical mapping is to review the geology, mineralogy and other critical parameters and construct a geometallurgical matrix. This matrix provides an objective base to then guide sampling and/or compositing activity for physical property and metallurgical testing. Depending on the project, an array of testing techniques can be used to characterize the ore and feed data into the geometallurgical model.While the range and number of tests needed is project-dependant, the geometallurgical mapping approach allows the development of empirical models or interdependent relationships, grounded by spatially-constrained real data. Extensive data sets collected using less expensive testing methods can be meaningfully correlated with results from complex specialty tests to yield realistic metallurgical recovery data.With geometallurgical mapping completed, the resulting database can be integrated into an overall 3-D block mine model. This means that metallurgical response can be used to realistically forecast the recoveries of specific blocks, perhaps sampled only by drilling. Mine planning can then incorporate the forecasted metallurgical response and generate future project cash-flows; opening the door to economic optimization of the mine exploitation."

Jan 1, 2004

By S. Banisi, M. Pourkani, A. Kargar, D. Hamidi, M. Sarvi

"Flotation circuit of the Sarcheshmeh copper mine, which processes 40,000 t/d of ore at 0.9% Cu, consists of rougher, cleaning and recleaning stages. To study the stage recovery of copper, one of the eight identical flotation banks was selected for sampling. It was observed that 17% of copper goes to the tailings and the lowest copper recovery was for particles coarser than 105 microns. The third five-cell unit of this bank not only did not recover appreciable amount of copper but also decreased the concentrate grade. The grade of the last five cells was lower than the feed grade suggesting that mixing of the concentrates of the three units was not beneficial. To alleviate the problem, the concentrate of the first four-cell unit was directed to the cleaners feed box (i.e., by- passing the regrind mill). This increased the overall copper recovery by 1.7 %. Also rather than the current practice of adding the reagents only at the feed tank (i.e., 100-0-0%), various combinations of stage addition were examined. It was found that 75-25-0% addition regime could increase the total copper recovery by 1.3%. At the recleaning stage in order to increase the final copper concentrate grade, a froth washing system was used. To ease the maintenance of the system, a shower type washing system was installed. The optimum wash water superficial flowrate was found to be 0.06 cm/s. Continuos sampling of the recleaners with and without wash water over a period of two months showed an increase of 1.5% in the final copper concentrate grade at constant overall copper recovery.INTRODUCTIONThe Sarcheshmeh copper ore body that may rank as third or fourth largest in the world contains 1 billion tonnes averaging 0.9% copper and 0.035% molybdenum. It is located in southeastern Iran and has been processing 40 000 t/d of ore since 1982. The mine produces 100 000 tonnes of copper and 2200 tonnes of molybednite concentrate per year.After three stages of crushing, the ore with a F80 (80% passing size) of 12.7 mm is fed to eight parallel ball mills in closed circuit with cyclones to produce a product 70% finer than 75 microns. The concentrate of rougher flotation circuit is ground; rougher tails constitute the main component of the plant final tailings. A concentrate with an average grade of 31% Cu (chalcocite and chalcopyrite) is obtained after cleaning and re-cleaning stages. Total recovery of the plant varies between 83% and 87%, depending on operating conditions and ore type."

Jan 1, 2001

By J. A. Meech, R. J. Tucker

"Since the establishment of froth flotation as an effective method of mineral beneficiation there has been both academic and industrial interest in the levels of the various reagents required to perform the desired separations. Academic interest was spurred by a desire to understand the mechanisms involved - industrial interest by a need to improve the efficiency of the process. These efficiency improvements can take two forms: cost reductions due to reduced reagent consumption and/or improved separation efficiencies. The latter are indicated by either improved grade-recovery relationships for removal of a valuable mineral from gangue, or improved separation of two similar valuable minerals.The processing of lower grade ore bodies at higher tonnage rates has necessitated increased interest in both reagent consumption and metal recovery. Furthermore, the development of accurate and functional on-stream analysis equipment in the 1960's and 1970's has allowed for a better understanding of the dynamic processes involved in a flotation circuit and has required a more concrete statement of the relationships and reactions between the minerals and chemicals in the flotation pulp. Development of these relationships is necessary in order to make use of on-stream analysis to control the process at, or near its more efficient level."

Jan 1, 1984

By Richard Morland

Some simple and fundamental objectives To challenge and inspire our people to embrace safety as a value ?A stand for safety as a value ?A stand for our people ?A stand by our people ?Prevent harm to our people ?Eliminate suffering for individuals, families, friends, colleagues

May 1, 2010

By H. Agnerian

"A survey of 925 mineral property transactions worldwide was carried out between 1987 and 2004. These mineral properties with reported Mineral Resources include 457 gold properties, 322 base metal properties, and five platinum group element (PGE) properties. Based on constant Canadian dollars, the results of the survey indicate that:• In general, unit metal values in the ground (e.g. $/oz Au or $/lb Cu) have kept pace with the changes in the respective metal prices during the period of the survey.• A general decrease in unit gold values in the ground has occurred from about $57/oz Au in 1987 to about $11/oz Au in 2002 for Canadian mineral properties, with the exception of a peak of $58/oz Au in 1996.• A similar trend for mineral properties has occurred in the United States, but with lower unit values, in the range from $1/oz Au to $10/oz Au during the last three years of the survey. • Unit metal values in the ground for gold properties in Canada were higher than for those in the rest of the world.• Unit metal values in the ground for copper properties in Canada were in the mid-range compared with other countries in the rest of the world; the United States and Australia were higher and Latin America, Asia, Africa, and Europe were lower than in Canada.• Unit metal values in the ground for zinc properties in Canada were also in the mid-range compared with other countries in the rest of the world; Latin America and Europe were higher and the United States, Australia, and Asia were lower than in Canada.• Unit metal values for nickel properties in Canada were highest compared with other countries in the rest of the world, followed by the United States, Australia, Africa, and Asia.• Gold values in the ground in Canada have ranged from 6% to 14% (with an average of approximately 10%) of the gold price.• The unit values of base metals in the ground have been in the order of 2% of the quoted metal price, during the period of the survey."

Jan 1, 2006

By H. C. Horwood

INTRODUCTION THE Argosy Gold Mines, Limited, which joined the ranks of active Ontario gold producers during the summer of 1936, holds a group of 21 claims on Casummit lake, in the Patricia portion, district of Kenora, northwestern Ontario. The Company is developing and mining goldbearing quartz veins that occur in a series of greywackes and slates of probable Keewatin age. The writer made a geological examination of the property and the surrounding area for the Ontario Department of Mines during the early part of the field season of 1936. This paper is a report on the general geology, structure, and ore deposits at the mine and is based almost entirely on data compiled during the examination. HISTORY Mineralization was first discovered on the property in May, 1929, by A. F. Hewitt, who, with J. A. Borthwick, decided that the country had prospecting possibilities and commenced work in April. Mr. Hewitt staked, and with his partner, J. Ziyone, still holds the group of claims lying immediately east of the present Argosy holdings. Mr. Borthwick staked six claims, K.R.L. 9,681 to 9,686, inclusive, adjoining Hewitt's on the west and later added claims K.R.L. 9,733 to 9,740, inclusive, to his holdings. F. Fiskness, who was also prospecting in the region, discoveted No. 1 vein on Borthwick's claims, and with his two partners, L. Parth and H. Jones, staked claims K.R.L. 9,758 to 9,763, inclusive, to the northwest of Borthwick's and Hewitt's ground. In July, 1929, the Casey Mountain Operating Syndicate, which held ground to the northwest, secured an option on Borthwick's claims. The Fiskness-Parth-Jones property was added in January, 1930, to protect the west dip of the veins. During the winter of 1930-31, the veins were explored by diamond drilling, No. 2 for a length ?of 900 feet and a vertical depth of from 51 to. 375 feet? and No. 3 .t~ a slope depth of 175 feet. I~ August, 1.931, after the msrallat10n of a miming plant, the Casey Summit Gold Mmes, limited, was incorporated to take over the property from the Syndicate. The Maple leaf Mines optioned a controlling interest in the stock in August, 1933, and on September 17th, 1934, brought a 50-ton amalgamation mill into production. From early in October to December 27th, 1934, when the mill was closed down, 4,094 tons of ore were treated to yield 887.89 ounces of gold and 87 .26 ounces of silver( ! ).

Jan 1, 1937

By I. Haskett

ABSTRACT The Redwater pool, in north-central Alberta, was discovered in October, 1948, and at the end of 1950 was about 85 per cent developed. Production is from a Devonian coral limestone reef and is found at an average depth of 3,150 feet. The pool has an estimated .productive area of 37,000 acres, and a maximum oil zone thickness of slightly over 200 feet. Wide variations exist in both type and values of porosity, with the average value determined for the reservoir being 6.16 per cent. The total stock tank oil in place is about 1.24 billion barrels. The crude has a saturation pressure of 485 psig, com-pared to the original value of 1,050 psig for the reservoir, and the principal recovery mechanism so far has been the natural water drive. Cumulative production to January 1st, 1951, has been about 15.5 million barrels. These withdrawals resulted in a reservoir pressure decline of slightly over 100 psi. Predictions of future behaviour indicate that the water drive will not be of sufficient magnitude to maintain the reservoir above saturation pressure past 1953, and that, with natural depletion, the pool will be produced largely by a solution gas drive. Pressure maintenance by water injection has been considered and the possibility of raising the pressure to the original value of 1,050 psig is also discussed. INTRODUCTION WITH the discovery of the Lewduc pool, early in 1947, the Devonian limestone became the major geological formation contributing to Western Canada's rapidly growing petroleum reserves. Redwater, discovered in October, 1948, is now the largest known Devonian pool in Canada, with a recoverable reserve estimated at approximately 500 million barrels. Until recent years, the knowledge of the nature and characteristics of this type of limestone reservoir has been comparatively limited.

Jan 1, 1951

By Johnna Muinonen

"The Thompson Mill processes ores from the Thompson and Birchtree Mines. While the Thompson ore has very little magnesium containing gangue, the Birchtree orebody consists of veins of massive sulphide in a rock matrix that contains a high proportion of magnesium silicate minerals. A significant fraction of the magnesium is floatable, which lead to MgO levels varying from 3-11 wt% in the Birchtree concentrate. The magnesium in the concentrate causes a higher operating temperature in the smelter, reducing furnace life.Birchtree ore represented 20-30% of the mill ore receipts prior to October 2003. Since then the fraction of Birchtree ore has increased to 50%. A reduction of the MgO in concentrate to less than 3% in the total mill concentrate was required to allow safe and economic smelter operation.In October of 2002 a miniplant was set up to simulate the Birchtree plant circuit. Several flow sheet modifications were tested that led to a proposal for a circuit having increased cleaning capacity for the scavenger concentrate and a recleaner on this concentrate. Addition of CMC in rougher cleaner feed was also found to be required. The solution was confirmed through pilot plant testing in the mill in December of 2002. A full-scale installation was designed, engineered, and installed between February and September of 2003 with commissioning in September and October of 2003. Target metallurgy was achieved one week after start-up on slurry to coincide with the Birchtree Mine tonnage increase. This paper highlights the development, design and commissioning stages of the project.The new MgO rejection circuit has successfully allowed the processing of Birchtree ores producing concentrate consistently below 3% MgO. In addition, the new circuit increased overall nickel recovery in the mill.INTRODUCTIONThe Thompson Nickel Belt located approximately 700km north of Winnipeg was discovered in the early 1950’s. Inco first produced nickel from the area in 1960. Over the years the mill has processed several ores from different ore bodies in the area. Currently the Thompson Mill processes two significantly different ores from two mines, Thompson and Birchtree. The Thompson ore is a massive sulphide orebody hosted in schist, containing feldspars, quartz and biotite. Thompson Ore is characterized by high nickel recoveries and clean, low MgO containing concentrates (<2.5% MgO). The Birchtree ore is ultramafic and contains a high percentage of Mg-silicates such as serpentine, chlorite, biotite, amphiboles and talc. Some of these Mg-silicates report to the nickel concentrate and prior to commissioning of the MgO rejection circuit the Birchtree nickel concentrate typically contained 5-8% MgO"

Jan 1, 2006

By J. B. Boisvert, P. Oshust

A significant source of uncertainty in the diamond resource contained in kimberlite pipes is the volume of the pipes. Often the material within a pipe will be mined as ore, leaving the actual geometry of the pipe as a significant source of uncertainty. It is desirable to use stochastic techniques, rather than deterministic methods, to model pipe geometry because stochastic techniques generate multiple realizations that are reproducible and can be used to assess uncertainty in pipe geometry. The proposed methodology uses sequential Gaussian simulation of pierce point locations interpreted from drillholes through a kimberlite pipe. Kimberlite pipes are approximately cylindrical in shape; therefore, the data are transformed to cylindrical coordinates to facilitate the simulation of pipe geometry. Rather than using xyz coordinates to define the pierce points, z, ??and pipe radius are used. The radius variable can be simulated in z-??space to generate multiple realizations of pipe volume. Uncertainty in the volume of the pipe can then be evaluated. This methodology is demonstrated with a kimberlite pipe at BHP Billiton’s Ekati diamond mine.

Jan 1, 2008

By W. E. Kuhn

Introduction The work, of which some of the results are described in this paper, was started with the object of investigating the properties of certain binary alloys of titanium made from powders. Our main interest was in the possible use of such alloys in gas turbines. We were attracted to titanium, as have been others, by its high melting point (I,724° ± 11°C.), its low density (4.54), and the likelihood that, if a relatively wide use could be found for the metal, it might become available in commercial quantities at a fairly reasonable price. The readiness with which the metal reacts with hydrogen, oxygen, and nitrogen was recognized from the very beginning. At the same time there seemed a good chance that alloys could be produced which, because of the formation of protective films, would resist the attack of these and other corrosive agents. No specifications were drafted to cover the &apos;quality&apos; of the titanium hydride powder which was used in our work and which was, to judge by the results of a few preliminary experiments, the most useful source of titanium then (1944) available in sufficient amount for our purpose. During the course of our work, the need for such specifications became very clear (see Sections 9 to 12 of this pa per). Even today, lack of knowledge regarding the effects on titanium of impurities, some of which may later be looked upon as essential elements in commercial alloys of titanium, and difficulties in manufacture, make the preparation of specifications for commercial titanium and titanium compounds a doubtful procedure. The papers presented at the 1948 Symposium on Titanium, sponsored by the U.S. Office of Naval Research lend colour to this view. At the time our work was commenced, one had to depend upon the manufacturer to supply what he considered to be his &apos;best&apos; material. It may be some time before we can ask for more than this, the question as to what is his &apos;best&apos; being left to the manufacturer to decide. However, in this connection the results of our study may be of some value and on that account we are constrained to publish them.

Jan 1, 1950

This paper generalizes open stopes into elliptical cross sections and applies the results of calculations based on the mathematical theory of elasticity to indicate stress distribution on the boundaries of such stopes. These show both compressive and tensile stresses and provide an ex-planation for the development of excessive dilution in shrinkage toping. Introduction T HE stress pattern around shrinkage stopes is identical with that around other stopes under the same physical conditions. However, a shrinkage stope ends as an unsupported open stope, and the method i limited to the stress range within which the rock is generally self-supporting. If it is acceptable to generalize the outline of a shrinkage stope into an elliptical cross section, then the graphs of Geldart & Udd (1) (see also Panek (2) and Denkhaus (3)) provide a good base for approximating the stress distribution as mining progresses. However, with failure conditions in the walls, the axis ratio, as cut

Jan 1, 1964

By Greg Yuriy

Over the past two decades, Vale Canada has used discrete-event simulation in a key role to support many underground mining studies. Traditionally, general purpose simulation software was developed for manufacturing and service applications. Not until recently have Mine Designers and Simulation Specialists been able to model the dynamics of underground mining scenarios without extensive manipulation of the inherent tools and entities contained within these simulation environments. This paper discusses Vale Canada?s past experiences with a variety of simulation software, describing model development methods and highlighting some of the lessons learned. The paper concludes with a review of recently considered software and provides a framework of desired attributes/functions for modeling mining scenarios.

Aug 1, 2013

By J. M. Menacho, J. M. Reyes

"Batch and continuous regrind tests were conducted in 3 kW and 15 kW tower mill units, respectively. Single particle size classes of a chilean copper sulphide concentrate were employed in the batch tests, while a fraction of the plant stream was deviated to the continuous unit operated under different conditions.Results are interpreted in terms of the simplified grinding kinetic model energy-based and conveniently adapted to this application. Based on the above figures plus some industrial data supplied by MPSI Inc., a scale-up relationship was developed for the apparent specific rate of breakage siE, as a function of the net power draw P, i.e.siE = siE text (P/P test) 0.089This equation fit very well the available data at the three scales and its application to regrind 4400 t/day of rougher copper concentrate from 70% below 325 Tyler mesh to 95% below same mesh, involves around 30% energy-saving compared to standard ball mill for same grinding task.INTRODUCTIONImpact and abrasion-attrition breakage are two extreme mechanisms present in any grinding system in a proportion defined by specific design and operating conditions. Impact breakage is generally efficient for coarse grinding, while abrasion-attrition is adequate to produce fine particles. Efficiency of conventional tumbling mills decreases as fineness of the product increases, even though distribution of applied stresses is always much stronger than internal force distribution in the particles. On the other hand.in a vertically stirred ball mill like the tower mill, distribution of applied stresses and particle strengths are in the same order of magnitude, making possible nearly ideal abrasion conditions (1).Tower mill configuration includes a cylindrical body vertically mounted and provided with a central screw with flights to produce circulation of balls moved up through the inner region to return down by the external space. Fresh material can be fed into the top , center or bottom in order to assure appropriate agitation of suspended particles. Size reduction and evacuation rates should compensate settling of coarse particles to avoid sanding of the screw. Detailed description of the tower mill and its operation have been given elsewhere (2),(3)."

Jan 1, 1989