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By W. S. McDonald

PRACTICALLY all dusts derived from organic matter are explosive and instances are recorded of explosions-some of them extremely violent-having occurred in grain elevators and flour mills. While a discussion of the explosibility of dusts in general, doubtless, would be of more than academic value, it will be of greater interest, on this occasion, to consider various phases of the problems connected with the hazards arising from coal dust. Extensive and valuable research has been carried out during the past few decades on the subject of coal-dust explosions and a great part of this work has been concerned with the preventive effect of stone or other incombustible dusts. Four men have been outstanding in this very substantial achievement. The first is Dr. W. Galloway, who succeeded in demonstrating by experiments that one pound of coal dust mixed with 150 cu. ft. of air formed an explosive mixture. The next is Sir W. Garforth, who proved that stone dust is an effective preventive for coal-dust explosion. The third is G. Haon, and last but not least, L. G. Hill, both of whom laboured incessantly to produce a suitable stone-dust and a satisfactory method of application. Today, mining men all over the world are satisfied and convinced that stone dust, if properly applied, will prove effective in greatly minimizing, if not completely preventing, explosions of coal dust, as has been demonstrated in experimental mines, as well as in actual explosions, in practically every coal mining industry.

Jan 1, 1938

By F. Hashiuchi

In 1996, the Saganoseki custom smelter & refinery successfully shifted to a single flash smelting furnace operation and increased the copper production capacity to 450,000mtpy in 1998. As the next step, Saganoseki planned to further increase the productivity, especially in the area of P.S. converters and acid plant. As the results of modifications and operational improvements, the gas washing & cooling sections of the Saganoseki acid plant were consolidated from 3 to 2 lines, and increased the gas treatment capacity. The S02 converters in the acid plant were also modified to increase the acid production. By increasing the matte grade from 65 to 68%, six PS converters have been successfully integrated into four, while maintaining the production capacity and reducing the environmental burden in 2005. This paper discusses recent operational conditions and the results of implementation of technological improvements.

Jan 1, 2007

By C. O. Stee

IN the October, 1936, issue of the Canadian Mining Journal there was published a series of very comprehensive and exccellently illustrated papers by Mr. C. O. Stee and members of his staff dealing with Siscoe operations and ore-bodies. These were, in the order in which they appeared: Geology of Siscoe Gold Mine, by O. L. BACKMAN Diesel Power at Siscoe Gold Mines, Ltd., by C. O. STEE andE. A. BLOMQUIST Mining at Siscoe, by L. T. POSTLE and W. F. Engineering and Surveying, Siscoe Milling Practice, Research and Testing Laboratory, Assaying of Mill Tails and Solutions, BROWN(6) by P. A. TEEPLE (7) by L. E. DJINGHEUZTAN by L. RIVETT (8) by G. IRWIN (9) The Editor of the Canadian Mining Journal cordially assented to our suggestion that these papers be reviewed at the 1937 Annual General Meeting of the Institute, and the authors very kindly accepted our invitation to present such reviews . Of these courtesies, full acknowledgment is here accorded. To our readers, we commend the original papers in the Canadian Mining Journal. The summaries presented at the meeting follow. EDITOR. THE GEOGLY OF THE SISCOE MINE The Siscoe gold deposits lie in and near a stock of granodiorite, related to the Bourlamaque batholith, which has intruded highly folded Keewatin volcanic rocks .. The volcanic rocks lie to the north of a belt of Timiskaming sediments.

Jan 1, 1937

By D. Emadi

The ASTM B108 Mould and a Modified Mould were used to cast test bars under a variety of conditions: mould and pouring temperatures, mould coating and tilt. Mechanical properties were determined in the as-cast and heat-treated conditions. The ASTM Mould is less sensitive to casting variables. Enlarging the gating system and adding additional gates to the ASTM mould can improve properties in the tilt position. The reproducibility of properties in as-cast and T6 heat treated bars was investigated.

Jan 1, 2004

By L. S. Beck

"The Athabasca region forms part of the Churchill province of the Canadian Shield and is underlain by an Archean or Aphebian assemblage of rocks that underwent severe metamorphism and granitization during the Hudsonian orogeny (1750-1950 m.y. ago). In places, the eroded orogen is overlain by unmetamorphosed cover rocks (in-cluding the Martin and Athabasca formations) of probable Paleohelikian age. Basic dykes cut all the rocks of the region.There are innumerable vein-type pitchblende deposits and many syngenetic occurrences of uraninite in crystalline basement rocks. Evidence is presented to show that pitch-blende was emplaced during the final stages of the Hud-sonian granitization and followed the crystallization of syngenetic uraninite transitionally. In terms of P-T condi-tions, the pitchblende deposits belong essentially to Lindgren's mesothermal group.Based on the postulated uranium metallogenesis, the possibilities of finding further deposits of pitchblende and other types of uranium deposits are discussed."

Jan 1, 1970

By G. S. Ospanova

The results of complex processing sulphide copper ore and advantages of recovery of copper by vat and heap leaching, sorption, cementation and electrolytic solutions processing and utilization of waste material after heap leaching of copper for production of building materials were investigated. The combined chemical solvents with the additives of oxidizing agents are developed at the KazNTU. The solvents are inorganic or organic chemical reagents, which form complexes of Cu, Au, Ag, Pt, Ni, Sr, Co etc. Recovery of non-ferrous metals from solutions and purification of industrial waste waters is carried out on the base of using new synthetic and natural sorbents (from local raw materials) which are able to bind ions in both cationic and anionic forms depending on type of ligands and external conditions. Optimum parameters of copper sorption were determined. The developed wasteless technologies of copper extraction from sulphide ores with usage of new non-toxic solvents and accessible sorbents with full recycling of water are tested in pilot scale heap leaching, and are recommended as the ecological, economical and practical alternative to traditional methods.

Jan 1, 2007

By W. J. S. Craigen, G. E. Wittur

"In the context of today's continuously changing world, there are many factors which must be considered when attempting to assess the ability of Canada's primary copper producers to remain competitive in the face of increasing competition in world markets. In this paper, we have attempted to document those factors that will have the greatest impact on the future viability of Canada's copper industry, and to suggest possible strategies to fully utilize whatever inherent advantages Canada may have to enhance its competitive position. Technological factors related to the efficiency of precious and by-product metals recovery, energy type and utilization efficiency, production and sale of sulphur by-products, and control of 502 emissions are given high priority in this evaluation of Canada's future needs to remain competitive. Particular emphasis is placed on assessing the relative viability of hydrometallurgical versus pyrometallurgical processes for copper; to address uniquely Canadian conditions and problems. Due consideration is also given to the economic incentives required to allow Canada's copper producers to compete under anticipated world market conditions and to facilitate the continued development of Canada's copper resources. IntroductionWhen we try to assess the viability or competitiveness of any industry the bottom line is still usually, ""Can we produce a pound of product cheaper than the competition?"" Canada's copper industry is certainly no exception. However, as with most resource-based industries dependent upon exports, there are many factors which have a significant effect on the cost components which make up the total cost of producing and selling a pound of copper. It is desirable therefore to have as clear a picture as possible of the cost components, the major factors affecting them, and how they compare with the competition, particularly the third-world copper producers.In this paper we have attempted to provide a brief outlook for world copper markets and a brief overview of Canada's competitive position. We have also attempted to document those factors which will have the greatest impact on future production costs, and have suggested possible initiatives to utilize inherent Canadian advantages to enhance our competitive position. Special emphasis has been placed on technological initiatives designed to make full use of these ""advantages"", to develop superior beneficiation and extraction! refining technologies. Major factors considered in the present study are:"

Jan 1, 1986

By D. M. Hendrick, D. K. Fountain

Since the discovery by conventional prospecting of the Horne deposit in 1920, the Noranda area has produced 82 million tons of copper-zinc-gold-silver ore from sixteen massive sulphide bodies. Recent exploration in the area has consisted of systematic studies employing geology, geophysics and geochemistry. Due to the depth of the deposits being sought, surface geo-physical surveys are limited in their effectiveness as DIRECT indicators. However, because of the geological environment, surface geophysical methods, and the Induced Polarization method in particular, can be success-fully employed as INDIRECT indicators of ore deposits. Examples of survey results from various properties in the Noranda area illustrate the advantages and limitations of the Induced Polarization method as an exploration tool in this area.

Jan 1, 1971

By Ahmad Ghahreman, James McNeice

"Cerium is the most abundant rare earth metal and is often found in deposits along with small amounts of more valuable metals such as neodymium and gadolinium1. As a result, the production of cerium oxide often exceeds market demands, thus in some cases it would make more sense to remove the cerium from the process solutions before further purification. A common method of cerium removal is to precipitate CeO2 from the acidic leach liquors by raising the pH to oxidize cerium(III) to cerium(IV). This study investigates the oxidation kinetics using three oxidants; hydrogen peroxide, sodium hypochlorite, and potassium permanganate. The effect of oxidant, pH, cerium concentration and temperature on the oxidation kinetics will be discussed. Cerium oxidation in solutions with pH ranging from 1.0 to 4.0 was investigated at cerium concentrations ranging from 2.0 g/L to 16.0 g/L. A cerium recovery of 40% can be achieved at different conditions with each oxidant at room temperature, with higher recovery at 60°C.INTRODUCTION Over the last 70 years, the rare earth elements (REE) have become crucial components of modern technology. These metals are categorized as light rare earths (LREE) or heavy rare earths (HREE) by governments and miners based on weight, abundance, and therefore value. The minerals bastnaesite, monazite, and xenotime compose the majority of the world?s exploitable sources of these metals (Binnemans, 2013; Parker and Baroch, 1971). Geologists classify the LREE ores as „cerium group? minerals, approximately 50% cerium oxide by weight. The cerium group minerals monazite and bastnaesite compose the majority of world production, leading to an overproduction of cerium relative to world demand. This ratio of light to heavy REE in deposits has led to a phenomenon referred to as the balance problem (Binnemans et al., 2013). As an example, to produce 1 tonne of europium oxide from a bastnaesite deposit 450 tonnes of cerium oxide must be processed. This means that any push to increase production and access the value of the HREE metals will drive down the value of the LREE metals leading to diminishing returns (Zepf, 2016). These ores also contain measurable levels of thorium, subjecting them to complex radioactive waste regulations. During the 20th century, the USA was the largest producer of rare earth metals (REMs), primarily sourced from the Mountain Pass mine in California. However, due to a combination of market dynamics and regulations, China has dominated the market for the last two decades. The largest Chinese REE mine, Bayan Obo, produces rare earth (RE) concentrate as a byproduct of iron mining, decreasing their relative production costs (Gupta and Krishnamurthy, 2005). This mine alone represents about half of world bastnaesite production (Zhi and Yang, 2014). Rising demand for high-tech products has forced Chinese producers to commission other large mines, climbing to 90% of world production in the early years of the new millennium (Mancheri, 2016). This presents the west with a looming supply risk of these critical metals in the future."

Jan 1, 2017

By A. H. Winckers

"The Sullivan Mine and Concentrator are owned and operated by Cominco Ltd. and are located in the Rocky Mountain Trench, in Kimberley, British Columbia.The Sullivan Concentrator commenced operation in 1923 at approximately 2,500 tons per day. The concentrator was enlarged in several stages and by 1945 was treating 8,500 tons of ore per day. In 1949, the capacity of the concentrator was expanded to 10,000 tons per day with the completion of the sink and float plant, the installation of the rod mill, an underground crushing plant and a 4-mile underground and surface electric railway from the underground crushing plant to the concentrator. Throughput now averages 7,000 tons per operating day, or 2,400,000 tons per year.The concentrator operates 7 days per week, 24 hours per day while the underground crushing station operates 5 days per week, 24 hours per day. The ore is essentially a replacement deposit in argillaceous quartzite of Precambrian age. The ore bodies are massive deposits consisting of fine grained mixtures of sulphides, sometimes interbanded with the country rock and varying widely in their content of lead, zinc, iron and silicates. The principal economic minerals are galena and marmatite (7 ZnS:FeS). Iron is mainly present as pyrrhotite, and to a much lesser extent as pyrite. The intimate association of these sulphides necessitated the development of a successful differential flotation process before the ore could be beneficiated profitably."

Jan 1, 1981

By David E. Pearson

"There are many tests that can be used to characterize and classify coals, and describe their quality. One of the easier tests, and most versatile in its application, is petrography. Rank and coal type are precisely defined by petrographic evaluation, and in this paper they are compared with other definitions of rank and coal type. Brief descriptions are given of the various rank tests, and of rheological and coking tests used to describe coking-coal quality in Canada. Similarly, tests used to evaluate thermal coal quality are discussed. Finally, the use of these tests as parameters to classify Canadian coals is examined with reference to four coal classifications.Introduction Among all coals there are two independent variables that are required to evaluate coal quality. These are, coal rank and coal type (or composition), and although coal petrography can be used to precisely define them, other methods are often used to provide values that are, in fact, functions of rank and coal type. For example, volatile matter yield is used as a proxy for rank, and free swelling index is used as a proxy for coal type in the International Classification of Hard Coals by type. Currently, there are a number of methods in use in Canada to define rank. The approach taken here, (obviously the author's bias), is that Romax, the mean maximum reflectance of vitrinite, is both a quick and an accurate measure of rank. It is logical to compare the other techniques employed in the measurement of rank to this favoured method. Coal type is, in theory at least, simply a quantitative measure of the various varieties of coal. In practice, the microscopic entities are assigned to a Reactive or Inert category, and at that point objectivity fades from petrography. Despite this somewhat subjective approach, petrographic composition of coals remains an independent variable of such.importance that its place in the evaluation of coal is essential. In this paper, a variety of me.thods that are used to assess rank and coal type are reviewed and compared; the influence of these variables over other parameters that are used to determine the quality of metallurgical and thermal coals is examined, and their usefulness in coal classifications is discussed."

Jan 1, 1985

By R. Wang

"Under high stress conditions, rock bursts, borehole breakouts, and spalling events are common phenomena that occur around underground openings. In general, together these three phenomena represent brittle failures of an intact rock mass; however, individually they reflect different failure modes under high stresses. After analyzing and comparing the stress-to-strength criteria for rock bursts, borehole breakouts, and spalling events, proposed by previous researchers, it is found that these brittle failure phenomena share common stress-to-strength prerequisite. The stress-to-strength preconditions for brittle failures can be defined by the ratio of the maximum tangential stress around an underground opening to the uniaxial compressive strength (UCS) (s?max/sci) or by the ratio of the maximum far-field principal stress to the UCS (s1/sci). Both these indicators can be used to reflect the same stress preconditions. For s?max/sci, a ratio of 0.4±0.1 represents the critical stress requirement for brittle fracture. However, for s1/sci, a ratio of 0.15±0.05 should be considered as the critical stress requirement. Numerous engineering case studies and analysis of rock mechanics based on the Hoek-Brown criterion also verify these two stress-to-strength preconditions. Here, these two indicators are presented with an error range because complex rock mass quality ratings, lithology, and geotechnical conditions have profound impacts on the stress-to-strength preconditions for brittle failures. INTRODUCTIONHigh stresses are one of the most important factors that must be considered when undertaking underground rock mass projects (Kaiser et al., 1998). Wang et al. (2009) reviewed current progress in the evaluation of high stresses and their corresponding criteria. However, after clarifying the definition of high stress, civil engineers need to understand the deformation and failure behaviors of rock mass around an opening under high stresses. Under high stress conditions, the deformation of rock masses around an opening can be categorized into two groups, i.e., severe brittle failures (or rock bursts) and compressional plastic deformation of the surrounding rock mass, as indicated in Figure 1."

Jan 1, 2015

By B. Hohenstein, B. McBain, B. de Jong

"The automated fire assay system (Fast In-line Fire Assay or FIFA) has not found acceptance in the Au mining industry as the lower measurable limit of 0.20 ppm did not allow Au tailings to be measured with confidence. The development of arrested cupellation has overcome this hurdle which was a limiting factor in the FIFA 1 process. In the new automated fire assay process, automated sample preparation, fluxing, fusion and separation of a Pb button are essentially similar to the FIFA 1 process, albeit with some improvements. However, the game-changer is the development and incorporation of arrested cupellation into the automated system, now called FIFA 2. The purpose of arrested cupellation is to reduce the 50 g Pb button to a 5 g Pb button by partial cupellation in a specially developed arrested cupellation system thereby concentrating the Au in the Pb by a factor of 10 and in so doing moving them into higher concentration ranges in the mini-button where they can be read on the spark spectrometer. Results show that concentrations down to 0.02 ppm Au in geological materials can now be determined using arrested cupellation in the FIFA 2 process, an order of magnitude improvement over FIFA 1.INTRODUCTION Traditional fire assay for Au has remained virtually unchanged for 3000 years. It has survived for so long because it is accurate, has relatively low detection limits and is relatively inexpensive. However, it is labour intensive, has a long turn-around time (typically at least 7 hours), is environmentally unfriendly and exposes assay operators to potentially unsafe conditions (toxic fumes, toxic dust and extreme heat from furnaces). The NiS collection method is not as effective for the assay of Au as it is for the PGEs. A rapid, accurate, cost-effective method for the determination of Au and the Platinum Group Elements (PGEs) in geological materials would be a tremendous benefit to mining companies. Many of these objectives have been met by the FIFA 1 (Fast In-line Fire Assay) developed some 15 years ago in which automated methods have replaced the manual procedures which are part and parcel of conventional fire assay. However, concentrations below 0.2 ppm have been very difficult to achieve with sufficient reliability."

Jan 1, 2017

By J. Doucet, C. Price

In an industrial setting, operational changes are continually introduced, driven by new technologies or changing economics. Because of day-to-day variability, quantifying the impact of these changes based on metallurgical performance requires long trial periods to achieve statistically significant results. Tools and techniques developed by the mineral processing group at McGill University have allowed for direct measurement of process variables (e.g., bubble size, gas and solid holdup). Two case studies are described where direct measurement techniques were used to evaluate: a) a new rotor stator mechanism; and b ), the introduction of a new frother type. Application of these methods has accelerated the evaluation of process changes and improved confidence in results.

Jan 1, 2009

By Jian Li, Robbie McDonald, David Robinson

"The pressure oxidation of sulfide minerals at temperatures above 200°C enables the extraction of base metals, improves the extractability of gold from refractory ores, enables solubilisation of PGEs and can be used to hydrothermally upgrade base metal-containing feeds. Fundamental studies reveal that the solution chemistry (and mineralogy of the solids) during pressure oxidation can be manipulated with outcomes that include (1) increased leaching rates, (2) lower oxygen requirements and (3) the formation of chemically more stable residues. This paper presents examples describing how these outcomes might be achieved based upon fundamental investigations.INTRODUCTION The application of pressure oxidation to the processing of gold ores and concentrates dates back several decades and continues to be the process of choice at operations such as Pueblo Viejo (pyritic gold) which host the largest autoclave of its kind in the world (Barrick Gold Corporation, 2016). Commercial application to the processing of base metals and PGMs resides with long established processes such as the Sherritt process, ore specific applications such as by Noril’sk, at Sepon etc. or has not proceeded to date beyond pilot scale testing (e.g. Phelps Dodge, CESL, Activox, Platsol). Recently there has been significant interest in hydrothermal upgrading options for concentrates including the NONOX and Toowong processes (Rohner et al., 2016; Weidenbach et al., 2016). The latter options suggest directions where sound knowledge of the underlying fundamentals enables novel outcomes and efficiencies to be obtained. It comes as no surprise that investigations similar to those underpinning these developing processes can be traced back several decades. It is not the subject of this paper to provide a historical perspective of the relevant autoclave chemistries but rather, to present some potential opportunities suggested by studies in our laboratories. Topics to be discussed in this paper include (1) control of metal extraction rates, (2) control of iron-residue composition and (3) control of sulfur oxidation and hence acid generation and oxygen requirements. The work described will focus upon the pressure oxidation of a nickel concentrate."

Jan 1, 2017

By A. O. Dufresne

A Step which, it is believed, will prove extremely beneficial to the Quebec asbestos-mining industry was taken during 1931, when the asbestos mine operators of the Province assembled to work out a uniform method of naming the products of their mines. The outcome of several meetings was the drawing-up of a classification which defined, limited, and designated anew the numerous grades of asbestos marketed. It entailed no drastic departure from the existing processes of grading, nor any revolutionary changes in methods of testing, but aimed rather to perfect existing methods. The classification proposed has been accepted by all operators in the Province, who, from January first of this year, began introducing the new nomenclature. Unless one is conversant with the properties and mode of occurrence of chrysotile asbestos, with the unique milling methods devised for its recovery, and with the history of the development of their technique, he may not readily understand the basis of the new classification. For information on these and other data concerning the industry, the reader is referred to a recent publication, Chrysotile Asbestos in (Canada, by James Gordon Ross, issued by the Mines. Branch of the Department of Mines, Ottawa. The object of this paper is to present briefly some of the phases in the evolution of the classification of Canadian chrysotile asbestos, in the hope that the recent effort to standardize the marketable products of one of Canada's most important non-metallic mineral industries will open a field for discussion, fruitful in new ideas and constructive suggestions. The necessity for the grading of asbestos results fundamentally from the fact that the price per ton depends on the length of fibre. At all times in the history of the industry, the very limited available supply of the longer grades, as well as the requirements of the trade, have caused relatively very high prices to be paid for fibre over half an inch in length, while for the shorter grades the price decreases rapidly, and at a rate which bears no proportionate relation to the length of fibre.

Jan 1, 1932

ABSTRACT This paper details the work of RISKGATE, the largest Australian Coal Association Research Program (ACARP) occupational health and safety initiative to date. The program is an interactive online risk management system developed to maximize health and safety performance in the coal mining industry by implementing continuous improvement in managing major unwanted events. The comprehensive knowledge base covers tires, collisions, fires, isolation, strata control underground, ground control open cut, explosions, explosives, manual tasks, and slips/trips/falls. All major Australian coal mining companies contributed topic experts to this broad industry initiative: nine coal mining companies, more than 80 experts, and more than 400 days of individual time for knowledge-capture workshops.

Jan 1, 2014

By Richard J. Wardle, Ambrose F. Howse

The industrial minerals industry in Newfoundland and Labrador is a significant contributor to the provincial economy. The variety ofcommodities produced reflects the diverse geological environment from which they come. A highlight of the past decade has been the continuing development of dimension stone quarries, with producers now active in anorthosite, gabbro, granite and sandstone. Other dimension stone prospects have been identified and are in various stages of assessment and development. Western Newfoundland hosts a large resource of limestone, dolomite and marble. It provides raw material for industries that produce Portland cement, agricultural limestone and aggregate, as well as chemical-grade limestone and dolomite products. In western Labrador, dolomitic marble is quarried for use in the production of self-fluxing iron ore pellets. The recent opening of a new gypsum quarry at Fischells Brook signalled the beginning of a new era in the commercial production ofgypsum, a commodity which the province has produced since the 1950s. Hopefully it will emulate the nearby Flat Bay Quarry (now closed) which was a long-time exporter to markets along the U.S. eastern seaboard, in addition to supplying local demands. Oil production and continuing exploration in the Newfoundland offshore has renewed interest in local barite deposits for potential use in drilling fluids. Already there has been some production from the Collier Point deposit, and at Buchans, an existing plant is being refurbished to recover barite from a large tailings pond. Emerging new industries include the development of an antimony mine in central Newfoundland, the development of silica deposits near Labrador City for silicon metal production, and reactivation of the St. Lawrence fluorspar mine. The province has many deposits with development potential such as rare metals at Strange Lake, white marble at Roddickton and salt deposits near St. George's Bay region.

Jan 1, 2001

By Tracey Bodnarchuk, Philipp Mirzoev

Sulfate balance control is a common problem for zinc plants. Roast-leach-electrowin plants are mostly concerned with the over-generation of sulfates while for the HudBay direct leach plant both extremes are possible including potential necessity to buy sulfuric acid to replenish a sulfate-depleted circuit, which makes the problem doubly important. Quantitative methods were applied at the HudBay plant to analyze sulfate generation/depletion based on a local sulfur balance and sulfate extraction calculation in the leach circuit, using a Pb-tie method. Main factors were established influencing sulfate generation/depletion, including the critical role of Pb and pyrite. Regression analysis proved to be effective and allowed the quantitative prediction of Pb concentrations necessary to reach the equilibrium for the sulfate balance. This in turn provided a firm basis for a sulfate-control strategy realized through concentrate blend correction, which allowed the plant to fine-tune sulfate generation/depletion effectively reducing economic consequences of excessive/deficient sulfate generation.

Jan 1, 2015

By Tuomas van der Meer, Jukka Tanninen, Annukka E. Mäkinen, Mika Martikainen, Laura M. Nevatalo

The mining industry consumes huge water volumes and the waste streams typically contain sulfate, which has caused problems to many operations around the world. Discharge of sulfate to fresh waters is being restricted as the sulfate load increases salinity and causes problems when sulfate is reduced to toxic H2S by natural bacteria. To reduce fresh water consumption, internal water recycling had become a necessity in metallurgical processes. However, the recycling causes accumulation of sulfate and other components in water, causing problems to process performance and increases scaling in piping and equipment. Few technically feasible water treatment processes exist in the market that can be applied to decrease sulfate concentration below gypsum saturation level: biological sulfate reduction, membrane separation, ion exchange, evaporation and chemical precipitation. Some of these technologies are effective for treating wastewater, but there is typically a highly concentrated sulfate fraction left requiring still further treatment. Outotec has developed a sulfate removal solution, Outotec Ettringite process, which allows flexible control of residual sulfate concentration, thereby opening doors for increased water recycle within processes and control of the sulfate in discharged waters. In this article the results and benefits of this novel process along with examples of operating costs are presented.

Jan 1, 2014