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By James H. Nulty, Joseph S. Roti

INTRODUCTION During a recent panel discussion on the topic of millwater antiscalants, the question was posed: "What would you like to see in the future?" Answer: 'We need an antiscalant that: can be fed without a pump (no maintenance), functions on residual basis (no fault), can be tested for colorimetrically in sub-part-per- mi 11 ion concentrations (no guessing) and will recycle back to the mill from tailings (no cost).” Impossible? Based upon today's level of technology, such a product does not exist. However, a few of the qualifications listed above are certainly food for future thought. Meanwhile, progress is being made in upgrading three essential elements in this critical area of ore processing. They are: 1. Antiscalant reagent research and development. 2. On-line monitoring programs. 3. Reagent storage and feed systems. The objective of this paper is to out- line the current direction being taken in each of these areas and to present case histories as examples of how theory has been applied in field situations to better improve operations. LABORATORY SCREENING TESTS Recent technical papers have explained the various generic chemical raw materials which are available in the marketplace. While the merits of each chemical component are open to debate, the processes used by most major reagent suppliers to evaluate products in the laboratory are fairly standard. Common techniques incorporate both static and dynamic conditions in the search for the most cost effective product. Static Test Perhaps the most common test procedure used is based upon NACE Standard Test Method 03-74, which is "a laboratory screening test to determine the ability of scale inhibitors to prevent precipitation of calcium sulfate and calcium carbonate from solution." The objective of this test is to measure the change in calcium ion concentration in a container of saturated stock solution prepared from calcium chloride and sodium carbonate which is heated in a water bath. After 12 hours at constant temperature (160°), the mother liquor is pipetted into a beaker and a titrated for gm/l of unprecipitated calcium ion. A simultaneous test is performed on stock solution with antiscalant added. The results are then charted to determine the most effective antiscalant (with respect to preventing precipitation of calcite). It should be noted that this procedure examines only the ability of a chemical additive to retain calcite in a saturated solution where thermal stress is applied. This is commonly referred to as sequestration or stabilization. It has been documented that products which act in this manner (i.e., inorganic and organic phosphates) are good scale inhibitors. However, low molecular weight anionic polymers function in a much different manner by distorting calcite crystal size, shape and charge density, thus preventing scale formation. Because of this different mode of operation, static tests may not prove conclusive where polymers and sequestrants are being compared. The simplicity of this test makes it easily adaptable for field use, although modifications are often made.

Jan 1, 1986

By Terrence D. Chatwin, James Hendrix

Based on the findings within their report to Congress, the US Environmental Protection Agency (EPA) announced that it had decided not to regulate mining wastes under the hazardous waste regulatory program. However, they found that some mining wastes are hazardous and may be causing environmental damage. Cyanide wastes from heap leach operations were included in this group. In evaluating the effects of cyanide use in mining one finds a significant lack of information on the fate of cyanide in soils. Cyanide attenuation and degradation of soils is important, because ground water is a major potential pathway for cyanide contamination. There is a strong potential for cyanide to be removed from solutions as it migrates through soils· by volatilization, chemical reaction, adsorption, oxidation and biological processes, but no definitive investigation has defined these mechanisms adequately to be able to predict the fate of cyanide in soils.

Jan 1, 1998

By Mark L. Mott, Michael P. Synder

The Mine Safety and Health Administration has developed a program to improve the decision making process of personnel involved in mine emergency situations. The Mine Emergency Responsiveness Development Program (MERD) has been designed specifically for fires and explosions in underground mines. This program addresses the responsibilities and organizational requirements that are necessary during rescue and recovery operations of a mine emergency . Specific skills and knowledge are required to manage an organization of personnel under conditions of intense stress, such as a mine fire or explosion. As a result, the MERD program develops these skills by providing role playing emergency simulations. This role playing provides the participants with the opportunity to experience problems, explore solutions and interact with other personalities which may exist during mine emergency situations. This paper presents the standard procedures for the MERD program developed by the Ventilation Division of the Pittsburgh Health Technology Center.

Jan 1, 1991

By A. Russell, M. N. Hughes, Jack Barrett

The bacterial oxidation of arsenopyrite has been shown to be an efficient, economic and environmentally acceptable method for the liberation of any gold content . The mechanism of the process is not certain but is usually considered to involve direct and indirect reactions with respect to bacterial involvement. The direct reactions are those in which the bacteria attached to the mineral surface cause its dissolution, with dioxygen being the oxidant. The iron(III) produced in solution is the chemical oxidant in the so-called indirect reactions. Barrett et al 2 showed that a synthetic bio-oxidation solution (with no cells present) could dissolve up to 15% of an arsenopyrite sample, the products of the chemical oxidation being iron(II) and arsenic(III). This paper describes an extension of the investigation of the chemical process and its imp! ication for the mechanism of the bio-oxidation of arsenopyrite.

Jan 1, 1990

By Hugh K. Herbert, R. John Watling

Laser Ablation-Inductively Coupled Plasma-Mass Spectrom­etry (LA-ICP-MS) has been used successfully to "fingerprint" gold in forensic investigations within Australia and abroad. By comparison of the elemental associations it has been possible to relate gold to specific mineralising events, mines, bullion samples and fabricated articles. The methodology facilitates identification of the provenance of gold thereby providing definitive scientific evidence in criminal investigations. "Gold" samples for analysis span a wide range of materials with many requiring exhaustive prior separation and treatment to present the contained gold in a chemically "unmodified" state, and in a form, suitable for LA-ICP-MS fingerprinting. The quality of the fingerprint, and hence its value in evidence, is directly related to the rigours of prior sample preparation and evaluation, to an appreciation of the history of the gold under investigation, and to the skill of the analyst.

Jan 1, 1995

By V. Arad, S. Arad

Besides the conservation and closing activities, an important issue to achieve is the environmental rehabilitation of the mining perimeters, also assuring the continuity and sustainable development of the mining activity in the Jiu Valley. Modifying and depleting the soils by mining works and dumps of mineral waste as a result of coal mining and tailing is one of the important aspects. The paper’s aim is to analyze which are minerals and resources policies of our government and to adopt measures for sustainable development in the coal mining in this region. The measures to reduce the instability risk for the mining works and waste dumps, which could affect the underground mining constructions or the related surface areas, were consider. It is most important to establish the priorities in order to obtain a high efficiency by combining the measures according to the environmental analysis and risk assessment.

Jan 1, 2005

By H. Lyn Bourne

The is the 13th year for this column and the 12th in which the royalty data have been tabulated. There still exist some holes in the list of royalties that readers hopefully will fill. The most common mineral commodity is construction aggregates - either sand and gravel or crushed stone. In spite of their pervasive use nationwide, there are states from which the author has no information about royalties for either of these commodities. The reader can help - share information about these missing states and next year there will be fewer states without information. Severn Brown again sends helpful information from the Prospectors and Developers Association of Canada (PDAC). The PDAC Digest contained an article that distinguished between ‘net smelter return royalty' and ‘net profits royalty’ (Haase). The article also lists clauses and details that Brown suggests should be included in a net profits royalty contract.

Jan 1, 1994

By Cherie M. Tilley

The Stillwater Mining Company has acquired a Tunnel Boring Machine to expedite the mine development operations at its Stillwater Mine. The machine purchased by Stillwater was previously owned by Melbourne Metropolitan Board of Works, Melbourne, Australia. The machine was manufactured by Robbins Co. of Kent, Washington. The Stillwater Mine has an extensive system of footwall laterals which are required by the mine development scheme. The initial mine plan called for in excess of 30,500 linear meters (100,000 linear feet) of footwall lateral drifts at a cross section of approximately 3.0 meters in width by 3.75 meters in height (10 feet x 12 feet). A Tunnel Boring Machine was selected for this work. The Robbins machine number is 146-193. This machine is approximately 4 meters (13 feet 5 inches) in diameter. The machine was modified extensively prior to commencing operation at the Stillwater Mine.

Jan 1, 1989

By D. D. Harbuck, G. K. Green

The Bokan Mountain area on Prince of Wales Island, AK, contains vast quantities of heavy rare earth minerals. To lessen the US dependence on foreign sources, the US Bureau of Mines (USBM) investigated yttrium recovery from this ore. By sulfating the ore at 250 ° C for 1 hr at an H2S04:ore ratio of 1:1 and then water leaching the sulfated material for 1 hr at 20% solids and 25ºC, over 74% of the yttrium, cerium, and lanthanum were solubilized. Solvent extraction (SX), using a synergistic combination of OPAP and DEHPA, selectively loaded 100% of the yttrium. Yttrium was stripped directly as a solid using a 2M, 35 ° C NaOH liquor. When the OPAP/DEHPA mixture was tested in a continuous SX circuit, yttrium loading and stripping were 100% and 96%, respectively. The organic showed excellent recyclability properties with minimal solvent loss.

Jan 1, 1996

By H. J. Handewith, W. D. Coski

This paper describes the development and testing of the RAMEX excavation system. Incorporating a synergy of low velocity, high energy impact and kerf cutting, this machine offers a competitive alternative to drilling and blasting in hard rock. It is a boom mining machine that incorporates the features of a lightweight roadheader and it can mine nearly any shape opening in hard rock. The RAMEX Tunneler has been developed to satisfy industry demands for a non-explosive, flexible, continuous and rapid underground rock excavation system. It will produce minimum ground vibration in the urban environment and allow the flexibility necessary for thin seam mining conditions. It will also reduce initial ground support costs and has a minimum impact on rock integrity. Developed by RAMEX Systems with cooperative research provided by the U.S. Bureau of Mines, this system, could produce the next step in the continuing evolution of mechanical mining systems.

Jan 1, 1989

By Half Zantop

While the Andean belt of Chile contains porphyry copper deposits of considerable economic importance, only one major and several minor deposits of this type have been discovered in neighboring Argentina. There are no obvious geologic reasons for the country's apparent paucity of important porphyry copper deposits. Instead, a lack of exploration because of poor accessibility and past inadequate mining legislation may partly account for this situation. Western Argentina has porphyry copper prospects ranging in age from late Paleozoic to Pliocene. Many of these prospects have host rock and alteration characteristics that are very similar to those of large Chilean deposits. The economic potential of many of these prospects has not been tested adequately by geoehemical, geophysical, or chilling programs. A recently enacted mining promotion law and updated mining code removes some past exploration obstacles in Argentina, and makes in-depth exploration and evaluation of' the county's porphyry copper potential attractive.

Jan 2, 1981

By H. Suharyono, R. Hogg, P. Bunnaul

The flocculation of fine-particle suspensions by polymers is a nonequilibrium process whose performance is strongly influenced by physical as well as chemical variables. A standardized test procedure has been developed that provides quantitatively reproducible measurements of process performance in terms of the floc settling rate, supernatant turbidity and sediment compressibility. The procedure provides information on the development of flocs in response to polymer addition and on their degradation behavior during subsequent handling. Extensive experimental observations using a variety of solids and flocculant types have been used to develop criteria for reagent selection and process design. It is shown that the appropriate choice of reagent(s) is determined primarily by chemical factors (solid type, solution chemistry, etc.). However, actual performance depends more on physical variables, such as agitation intensity and the rate of flocculant addition. Some general guidelines for flocculant selection and process design in industrial applications are suggested.

Jan 1, 1994

By W. K. Tolley, D. G. Kotlyar

Oxidized sulfide minerals, commonly formed by weathering, are becoming increasingly important resources as primary sulfide deposits are depleted. Oxidation, in general, reduces selectivity and recovery in flotation. The objective of this research was to determine the mechanisms of oxidation and collector adsorption in sulfide systems as a step towards developing improved technologies for beneficiation of oxidized sulfides. Data from microcell flotation tests are combined with electrochemical and spectrophotometric measurements. The adsorption of ethyl xanthate (EX) on oxidized sulfides was characterized using AC impedance and voltammetry techniques, and correlated to flotation response. Oxidation resulted in an electrically resistive, nonporous surface layer. The floatability of chalcocite, chalcopyrite and pyrite was dependent on the extent of oxidation. Oxidation for one day or more at 65ºC suppressed chalcocite flotation. Oxidized chalcocite also inhibited flotation of chalcopyrite and pyrite. Oxidation caused decreased chalcopyrite flotation. Pyrite flotation, however, increased after oxidation.

Jan 1, 1995

By Larry D. Hartzog

For detailed information you are referred to "Heap Leach Solution Application at Rochester" by S. N. Dixon and A. L. Wilder which will be presented at the SME Meeting in Phoenix, January 1988.

Jan 1, 1998

By Gaither H. Kitchell

Introduction Fire assaying is an ancient method of determining the amount of gold and silver in geological materials. Today's commercial, mining, school, and private fire assaying laboratories still use this basic assaying method. One of the primary reagents used to collect gold and silver from the ore is litharge (PbO), or lead oxide. The Federal Occupational Safety and Health Administration's (OSHA) and the Nevada Division of Occupational Safety and Health's (OSH) have a lead standard. It states that a person exposed to airborne lead at concentrations greater than 50 µg/m3 (1.4 µg per cu ft) of air over an eight-hour period has gone beyond the permissible limit for health safety. It is not uncommon to get airborne lead concentrations of 1400 µg/m3 (40 µg per cu ft) in the flux/sampling area or 900 µg/m3 (25 µg per cu ft) around the gas/ electric furnaces during the fusion and cupelling phases. Therefore, any individual working in these areas for more than 30 days per year without proper protection is a likely candidate for lead poisoning. Lead In A Human Lead enters the body as a toxic substance by breathing it into the lungs and upper respiratory tract and by getting lead particles into the digestive system through ingestion. Smoking, eating, drinking, chewing tobacco and gum, or wiping a lead-contaminated hand across the mouth are all potential ways forgetting lead into the body. Lead taken in large quantities can actually kill a person in a matter of days. This is rare, however. The real hazard of lead overexposure is for the unsuspecting person who works in an unsafe lead environment for months or years. This individual can slowly receive damage, sometimes permanent, to the central nervous system, gastrointestinal tract, kidneys, blood, gums, and reproductive system. Safe Blood-Lead Level The Lead Standard states that the maximum safe blood-lead level is 40 µg/100 g (40 µg per 3.5 oz) of whole blood. It recommends 30 µg/100 g (30 µg per 3.5 oz) if a person is of child-bearing age. People not working around lead products normally have a blood level of less than 10 µg/100 g (10 µg per 3.5 oz). A person not adequately protected can exceed 40 µg/100 g (40 µg per 3.5 oz) in a few weeks by fire assaying only 100 samples per day per week. Studies show that some individuals have developed lead-related diseases with blood-lead levels less than 80 µg/m3 (2.3 µg per cu ft). Lead Poisoning Symptoms There is a long list of symptoms associated with lead poisoning. The most common are: a prolonged, sweet, metallic taste in the mouth; loss of appetite; anxiety and irritability; weakness and dizziness; nausea and tremors; and insomnia. Preventive Measures Based on the lead standard, a number of preventive measures can be taken to ensure that fire assay laboratory personnel frequently exposed to lead are protected against overexposure. First, the actual lead concentration within the assaying area should be determined. In Nevada, one can contact the Department of Industrial Relations, Division of Occupational Safety and Health for assistance in monitoring any laboratory. The agency will also recommend ways to protect against lead. This agency does the monitoring and provides an educational class on lead safety. This type of agency can be found in other states. Commercial consulting firms are also available, but they are expensive. Regardless of the technique used to determine lead concentrations, it is most likely that the average fire assay area exceeds the 50 µg/m3 (1.4 µg per cu ft) lead concentration limit. This is considered unsafe.

Jan 8, 1985

By G. Sciocchetti, G. F. Clemente, F. Scacco

INTRODUCTION Radon, thoron and their airborne daughter products may result in a significant biological hazard when they are concentrated in enclosed places such as mines, houses and caves. High concentrations of radon and its particulate daughter have long, been known to be a causative agent for lung cancer to uranium miner: (Archer 1973). More recently increasing concern has been expressed on the possible health hazards associated with long term exposures over large population groups to low levels of radon daughters (Cohen 1980, Stranden 1980). Due to its peculiar geological features, Italy has various natural environments where the content of uranium and thorium in the soil may increase underground radioactivity. The presence in Italy of many underground waters rich in radon may be considered a further important source of radon in underground mines. A preliminary survey of the radon and radon daughter air concentrations in italian underground mines was started in 1971 (Bottino 1973). Furthermore many studies (Sciocchetti 1978, Sciocchetti 1980, Clemente 1980) have been performed during the last ten year to characterize the natural radiation environment in Italy. It has been also demonstrated that 21OPb/21OPo skeletal burden in spa workers and non-uranium miners can be heavily increased by the exposure (short or/and prolonged) to high levels of radon daughter air concentration (Clemente 1980). All these studies have been of great help to put in the right prospective the radiation hazards linked to the underground working activity in non-uranium italian mines. Two main actions have been prosecuted from 1971 until today in order to evaluate in greater detail such radiation hazards and then, when needed, to obtain their reduction to levels which may be considered acceptable. The two actions may schematically described as the following: - Measurement of the radon and daughter (and thoron and daughter when needed) concentrations in most of the italian non-uranium mines. The assessment of the radiation hazards linked to both the annual average lung exposure and the 210 Pb - 210 Po annual average dose to the skeleton is then performed for each considered mine by taking into account the main parameters characteristic of the mine. - Set up of a national regulatory recommendation on the permissible limits for the radiation exposure of workers due to underground mining activity. Such recommendation have been established in 1978 and have been designed in order to implement a national radiation protection practice during the underground mining activity. In this paper a summary description of the results obtained during the execution of these two actions will be given. MATERIAL AND METHODS Measurement of Radon, Thoron and their Daughter Products The excution of the planned survey requires the availability of specific techniques and instruments for measuring the different parameters characterizing the radon, thoron and their daughter exposure in mines. A reference laboratory was set up for the development and the standardization of the measurement procedures. Measurements of radon, thoron and daughter concentrations are performed by various methods: instanteneous or grab sampling methods and continuous read out monitors. The radon concentration is usually measured by a modified version of the two filter method. Mine air is drawn into a polyethylene bag and the sample is there after injected into a two filter tube; after sampling the exit filter is counted by the alpha spectrometric technique. The measurements is completed in a total time of less than 25 minutes at a sensitivity level as low as 3.7 Bq/m3 for a tube volume of 15 1. The measurement of radon and thoron daughter concentration and of the relevant potential alpha energy concentration is performed by means of a portable spectrometric apparatus which was developed at our laboratory (Sciocchetti 1981). The device allows multiple operating modes: instantaneous or brief sampling period and automatic cycles; computer data processing is then provided. The instruments that measure continuously radon concentration over long periods of time are of two types: a continuous scintillation monitor and an automated two filter

Jan 1, 1981

By Kenneth P. Katen, Robert H. Trent

GENERAL DESCRIPTION Shortwall mining is one of the newest mining meth¬ods to be introduced into the world coal industry. The technique of shortwalling seems to have a number of origins, but it is generally agreed that it is an outgrowth of pillar-and-stall mining where timbering was employed as the primary means of roof support. In early opera¬tions the face was undercut by a shortwall cutter, hand¬bored, and blasted. The coal was loaded by hand or gathering arm loader. Australia, having experienced success with this method, advanced the technique through the use of mechanized roof supports in 1968. Although there were several attempts at shortwalling in the US, it was not until 1973 that Eastern Associated Coal Corp.'s Federal No. 1 mine successfully extracted a shortwall panel. Table 1 is a list of shortwall opera¬tions in the US as of April 1976. Shortwall mining is a method of mining in which a continuous miner cuts and loads from the short end of a rectangular pillar of coal while hydraulically powered self-advancing roof supports provide protective cover. Characteristics of a shortwall system include panel di¬mensions (Fig. 1) of 610 to 1219 m (2000 to 4000 ft) in length, face widths of 30 to 61 m (100 to 200 ft), straight-line ventilation, and production machinery, with the exception of roof supports, commonly used on con¬tinuous miner units. GENERAL REQUIREMENTS AND LIMITATIONS The justification for shortwalling is primarily eco¬nomic, i.e., increased production and recovery concur¬rent with savings in material and labor. The method also has a number of secondary benefits including the much needed progress it has stimulated in deep mine technology, the alternatives it presents to some of the problems resulting from the 1969 Coal Mine Health and Safety Act, and is perhaps a key to the solution of the enigmatic labor problems which plague the industry. The advantages of shortwall mining over continuous miner units include the following: a highly effective method of ventilation and dust control; a greater per¬centage of extraction (approximately 85%) ; fewer equipment moves, hence more efficient operating time; cost savings on materials such as roof bolts, rock dust, ventilation curtains, timbering materials, and the labor needed to supply, load, and transport these materials; a cyclical pattern of mining, each phase of which, i.e., development and retreat, lasts for approximately three months and appears to be psychologically motivating as well as highly productive; and improved safety. In addition to these positive aspects, a shortwall sys¬tem also has advantages over a longwall system, and these are listed as follows: the capital outlay for a shortwall system is one-third to one-fourth that for a longwall (1976 prices); the shortwall system utilizes equipment that is used on a continuous miner section, with the ex¬ception of the roof support system; there is a great deal of flexibility in areas with numerous gas wells and in areas where surface subsidence cannot be tolerated; the shortwall has reduced tailgate problems, since the tail¬gate entry serves as a return airway only; and the cyclical pattern of mining insures that the mining machinery pro¬duces coal even while the roof support system is being moved to another panel. There are several parameters which govern the se¬lection and use of a shortwall system. They are all of equal importance, and hence are not listed in any par¬ticular order. These are deposit size, seam height, seam inclination, roof and floor conditions, depth of over¬burden, subsidence and chain pillar extraction, man¬power, ventilation, and materials handling. Deposit Size Reserves available for shortwalling should be suffi¬cient for at least an eight to ten-year period, since this seems to be the effective life, without rebuilding, of a hydraulic roof support under average conditions. Of

Jan 1, 1982

By Leonard Harris

It gives me great pleasure to be here today to tell you a little about how Newmont Gold chose to use roasting at its Nevada operations for the treatment of its refractory gold ores.

Jan 1, 1992

By D. Hulse

"The science of “optimal economic pit design” has been highly refined in the last decades. Even with the proliferation of optimizing and heuristic algorithms exploiting ever faster computers, the most common input is a single block model and a single set of cost assumptions, each of which is an estimate and prone to errors. An analysis of price assumptions produces a suite of nested economic shells, each with its own quantities of ore, waste, grade, and profit, but due to irregularities in the mineralized body, the growth of these shells can be erratic. To control the impact of the errors of the model and cost assumptions when choosing the pit shell for design, graphs of pit shells characteristics, such as stripping ratio, cost per unit of product and profit/ton, can be analyzed to consider points with higher stability, or robust pits. Selection of robust shells for a pit limit and for push backs can help to understand the impact to profit and risk. The robust shells also guide the preferred solution sets for final pit and cutoff optimization. INTRODUCTION “An open pit mining operation can be viewed as a process by which the open surface of a mine is continuously deformed. The planning of a mining program involves the design of the final shape of this open surface.” Optimum Design of Open-Pit Mines, Lerchs, H. and Grossmann, I. Transactions C.I.M. Volume LXVIII 1965. Traditionally an analysis of economic pit shells and sensitivity was performed by varying the input metal price. This was done with both floating cone algorithms as well as early versions of the Lerchs-Grossmann (L-G) algorithm. This gave an indication of the pit sensitivity to price but since other variables also change, some with metal price (perhaps steel and equipment), and some independently (fuel and tires) the understanding of these different pits was restricted. In addition, a run of the program could take hours, making a detailed analysis of small changes unwieldy. The L-G algorithm was programmed by a variety of people and sold as part of commercial mining packages, however it was first and most successfully commercialized by Jeff Whittle in 1984. When Whittle’s 3-D™ was expanded to 4-D the parameterization of the economic inputs was considered and the ability to run a suite of “pit shells” became automatic. The competing NPV Scheduler™ program sold by DataMine™ offers similar pit shell analysis capabilities."

Jan 1, 2018

By Roy Norcross, Stephen Gos

For over 100 years Degussa has worked together with the min­ing industry not only providing quality products but also develop­ing technologies to support these products through value added goods and services. For cyanide, these technologies include leach enhancement processes such as PAL™ and Solidox™, and cyanide detoxification with peroxygen based processes such as SILOX™ and Caro's acid using our DegOX™ technology. Degussa has also made important advances in how sodium cyanide is packaged and shipped with our liquid NaCN plant joint venture with MSI, CYANCO in Winnemucca, Nevada, and our Advantage SLS™ solid to liquid cyanide delivery system. All of these innovative technologies developed to support NaCN in mining, provide value to our customers and show Degussa's commitment to Responsible Care·11.1 and dedication to product stewardship. With Responsible Care and the customer in mind, Degussa has developed Advantage CCS™ cyanide control system, which will soon be available for the North American market. Currently there are several CCS units in service installed by Degussa AG (Germany), and we are in the process of designing the next gen­eration of the CCS which should be completed by late '98. Based on our experience working with gold and silver mines all over the world, there appeared to be an opportunity to further assist our customers by providing a better more automated way to control their cyanide additions. By providing the mine with an accurate method for maintaining their desired cyanide levels in their leach circuits, we could help them avoid underdosing and the associated gold and silver losses, and overdosing the cyanide which not only wastes cyanide but may increase treatment costs as well. In the early 1990's, when we began to introduce our CCS units, there were several cyanide controllers and on-line analyzers avail­able. However, they appeared to be too complicated and not made to stand the harsh conditions inside a mill. This resulted in exces­sive downtime and poor analytical results. We also found that many units would be installed but not commissioned by the sup­plier. Based on these observations, along with filtration and con­trol problems on some existing units, Degussa decided to design its own cyanide control system based on our extensive knowledge of cyanide chemistry, using the best components available worldwide.

Jan 1, 1998