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By HJ Marais, J A. van Niekerk

An investigation was initiated by BILLITON Process Research and Gold Fields Limited for the efficient removal of thiocyanate and cyanide from leach solutions. This led to the development of the ASTERTM process, an acronym for Activated Sludge Tailings Effluent Remediation. The biological degradation of thiocyanate and cyanide in effluents provides an alternative treatment to the more traditional processes. This occurs with a large number of micro-organisms which include bacteria, actinomycetes and fungi. Cyanide and thiocyanate are degraded to ammonia and carbon dioxide. Most forms of cyanide-metal complexes are generally removed through a co.mbination of oxidation and sorption into the biofilm/biomass. Since the ASTER™ process has commercial applications, a patent has been lodged for the ASTER™ process. A culture containing thiocyanate degrading organisms has been deposited with the Australian Government Analytical Laboratories (AGAL). The identification of the bacteria is in progress. Tailings arising from a cyanidation process tend to contain cyanide and thiocyanate. The presence of these species prevents the recycling of this water upstream to a bioleach circuit due to its toxicity to the bacterial culture. Increasingly stringent legislation for the land disposal of cyanide containing solutions also necessitates the treatment of the solutions before disposal.

Jan 1, 2000

By Jean-Michel Rendu

Equipment capital operating costs represent a significant portion of the total cost of most mining operations, and a variety of computerized methods have been developed to assist in the selection and effective use of this equipment. The questions to be answered and the tools available to answer these questions vary with the type of mine to be analyzed, the stage of development of the mining venture, the size of the operation, the details required, and the technical or economic objectives to be reached. Even though a majority of publications are directed towards open pit mining operations, the underground environment is not neglected. In the early planning stages of a mining venture, equipment selection is the problem to be solved. The simplest computer systems are designed to' automate time consuming manual tasks. A data base is supplied to and maintained by the user, which describes the technical and economic characteristics of available equipment. The user specifies the physical environment within which the equipment will be used and chooses from the data base a combination of loading and transport equipment. The role of the computer is to detemine the production which will be likely reached, the associated costs, and other relevant statistics. This approach is most helpful when modeling small operations or isolated parts of larger operations.

Jan 1, 1989

By R. Bruce Thorndycraft

This paper will describe several modifications to design of con­ventional oxide gold heap leaching. They are targeted at reduc­ing costs and simplifying heap operations. These modifications were conceptualized during consulting work on over 90 differ­ent heap leaches. In 1995, a unique opportunity arose to imme­diately apply all of these design concepts to the permitting and construction of a new facility at the American Girl Mine in southeastern California. American Girl Mine has operated since 1987. In April 1995, the mine faced a situation with grave consequences for cash flow. Approval for mining of a new ore zone, Oro Cruz, had just been granted, after lengthy delays by California regula­tors. All existing pad space would be filled by October. Only 6 months were available, and new pad siting and design were still undecided. Permitting of a new pad had not begun. Options were quickly reviewed. A strong criteria for pad site selection and design was ease of permitting. There was also a strong desire to install a system that would achieve better met­allurgical recovery and reduced operating costs, compared to previous heaps at this mine. One site offered the best chance for rapid permitting. It was the site of the original 1987-90 heap leach. This already dis­turbed ground contained 1.6 million tons of heaped ore. The old heap had just completed detoxification and was about to be signed off as a Group C waste, ready for reclamation. Instead of recontouring and revegetating the old heap, which the reclamation plan anticipated, we offered BLM and the County something even better. We proposed to off-load much of the detoxed old heap, and reuse the space. The off-loaded material would be back-filled into the original open pit, imme­diately adjacent. While the footprint of the proposed new pad was much larger, the reuse of disturbed ground, and backfilling of the open pit, had very strong appeal to the regulators. Our permitting strategy included the technical design of the proposed new facility. Many of the new design details also appealed to the regulators, particularly the "zero active ponds" concept.

Jan 1, 1996

By Jack F. McOuat

This paper describes how Canada's mineral exploration and development industries are on the decline as is its mineral reserve base. Not surprisingly, these are being offset by extensive and growing participation by Canadian companies and personnel in many other countries. The paper illustrates the extent and origins of this foreign activity as well as the present and future impact on Canadian mining and mining professionals.

Jan 1, 1992

By Luis Elu, Andy Bolland, Jack Simmons

The gold refinery at Barrick Goldstrike Mines has increased production to more than 2,000,000 ounces poured per year while reducing the labor requirement. Safety and health has not been compromised with this increased production and in fact incident rates and exposures have reduced over the past five years. Streamlining procedures, improving ergonomics and the wise use of unique innovations has accomplished this significant achievement.

Jan 1, 1998

By Corale L. Brierley

This paper lists commercial bioheap and stirred tank bioleach operations and explains the status of these operations. A total of 17 commercial-scale bioleaching plants have been commissioned. Bioleaching plants are divided into two technology applications: bioheaps and aerated stirred­tanks. In bioheap leaching, secondary copper ores or sulfidic refractory precious metal ores are crushed and bioleached on pads. Stirred-tank technology is used to bioleach base and precious metal concentrates.

Jan 1, 1999

By Kenneth B. DeGraaf

The development of precious metal recovery processes using chloride systems has mostly evolved from the development of chloride based treatments for base metal concentrates or ores. The recovery of silver from chloride solutions within a process designed for the treatment of base metals usually is part of a solution purification stage. This paper discusses the development of the silver recovery stage used in the GCM HydroCopper process.

Jan 1, 1990

By Gary P. Marshall, Jeffery S. Thompson, Robert E. Jenkins

The effectiveness of the new DuPont Passivation Technology in eliminating acid generation from iron sulfides is presented. Passivation is achieved by treatment with a dilute basic perman­ganate solution. This treatment produces a thin impervious layer of iron/manganese oxide on the sulfide surface, providing a bar­rier to the environment so that the sulfide is not available for undesirable reactions such as the production of acid.

Jan 1, 1998

By Patricio A. Riveros

Various types of commercial ion exchange resins were evaluated with respect to their ability to extract gold from cyanide leach solutions. Large differences were found among the various resins in terms of selectivity and gold loading. The hydrophi­licity and the charge density appear to be the main factors that determine the resin characteristics. Polystyrene weak-base resins, such as Dowex MWA-1, exhibited the best all-round performance.

Jan 1, 1990

By Michael Drozd

The operation of an activated charcoal system has five separate unit operations. These unit operations have common points for CIP, CIL and CIS system, which vary widely in application. a. Absorption b. Desorption (Stripping) c. Acid Washing d. Reactivation e. Carbon Handling ( carbon transportation, sizing, de­watering, etc.) Cost optimization starts with the basic operating parameters (design philosophy) set down at the time of engineering design. This parameters undergo almost immediate change due to site specific ore requirements, throughput changes, operator requirements or reagent availability. Activated charcoal is sometimes viewed as simple, uncomplicated reagent that requires not optimization. To some extent, this statement is true, but under most circumstances, if the time necessary to optimize the use of activated charcoal is available, the effort is rewarded with significant savings. CPL-Carbon Link has embarked upon a program of supplying technical support with its activated charcoal. Several operation in the United States have under taken to have CPL-Carbon Link do an operational survey to determine if potential savings are possible. CPL-Carbon Link has offered to do these surveys for projects that are clients or simply would like to have CPL-Carbon Link review their operation. The information accumulated by CPL-Carbon Link is being used to attempt to fashion industry standards so that a common reference point came be establish for activated charcoal usage.

Jan 1, 2000

By Steve Vaughan

Canadian Regulation and Reporting Requirements High reporting standards are essential in developing and sustaining a strong confident capital market. As of February 1, 2001, technical reports on mineral exploration and mining work, must conform to the standards of the Canadian Securities Administrators (CSA) National Instrument 43-101. Only a ‘qualified person’ may supply the technical information on which a news release is based and must verify that the final version of the release is accurate.

Jan 1, 2003

By H. N. McLeod, B. C. Butler, S. R. Rice

Tius paper describes the key considerations for design of impoundments for gold mine tailings. Design options available for construction are presented. The key considerations for design of a safe, economic and environmentally sensitive design are discussed. The dam design must also balance these conventional considerations with the pragmatic aspects of construction and operations and the risk of system upsets. Case examples of tailings facilities in Canada and Papua New Guinea are discussed.

Jan 1, 1991

By Dan Slyter

This paper prov ides comparisons be­tween Merrill-Crowe and Carbon Adsorption pl Rnts 11sed for Pree ious Metal Heap Leach Operations. During the first stage of mine devel­opement, the question arises as to type of gold recovery circuit to be employed, Car­bon or Zinc. Several important factors to consider in answering this question are: Au/Ag ratio Solution grades Daily plant production Plant throughput required Plant gold inventories

Jan 1, 1992

By Bodo Peinemann

For more than 35 years Lurgi has been providing its fluid bed roasters on a world­wide basis. The current total annual capaci­ty of the 250 Lurgi roasters approaches 26 million mt of sulphide minerals, including gold-bearing flotation pyrite concentrates. While the stationary fluid bed has been uti­lized for roasting exclusively, Lurgi has now commercially introduced its Circulating Fluid Bed (CFB) technology for gold roasting in a successful effort to maximize gold re­covery.

Jan 1, 1990

By Ken Criley, Marc E. Orman

Identifying the optimum ultimate height for heap leaching ore requires the consideration of a number of competing factors. A primary limitation is the reduction in the permeability of the ore with increasing heap heights. At low permeabilities the heap can blind off, cause serious ponding and runoff, and become very difficult to rinse at closure. The authors present a laboratory methodology that has been successfully used on several projects to identify the maximum height for controlling heap permeability.

Jan 1, 1996

By D. Erik Spiller

A commercialized dry gravity concentrator is operating on an alluvial gold deposit in the Boludo Mining District, State of Sonora, Mexico. The technology base of the process is the Rotary Air Concentrator (a dry circular air jig) that recovers gold from the desert sand resource. An overview of the Mexican operation and the dry concentration technology is presented. Application of the dry technology to pretreat­ment of heap leach feeds and other heavy minerals is a pos­sibility.

Jan 1, 2000

By Marc E. Orman, Mark E. Smith

Regulatory and environmental concerns continue to broaden the range of mine wastes that must be capped with low permeabili­ty liner systems at closure. The mining industry has been a leader in developing liner technology for leach pads and tailings impoundments, but it is a newcomer to cap designs. Closure of waste piles, leach heaps and tailings require special design con­siderations. Factos such as differential settlement, surface ero­sion, veneer stability, vegetation and burrowing animals must be considered.

Jan 1, 1996

By Tong Deng, Yun Ma

Gold-copper ores have become important gold resources (von Michaelis, 1989), but the gold extraction from such materials posed a challenge due to the detrimental effect of copper species on gold cyanidation. Ammoniacal cyanidation process was rec­ommended (Muir et al., 1989) and practiced (Castello et al., 1992) for gold extraction from the gold ores which contain cop­per at moderate level mostly in form of oxide. This paper pro­vides an example to apply the ammoniacal cyanidation process to processing such a copper bearing gold ore.

Jan 1, 1996

By Gary L. Simmons

Aqueous pressure oxidation at low temperature, although desirable from a process engineering and operations point of view, presents unique problems when temperatures approach 160°C (320°F). In developing the pressure oxidation process for the Lone Tree Mine, elemental sulfur formation and agglomeration with pyrite proved to be a problem. This paper discusses some of the unique mineralogical and chemical characteristics of the Lone Tree sulfide deposit that make it amenable to low temperature pressure oxidation. Problems encountered during pilot plant operation and their solutions are also discussed.

Jan 1, 1993

By John W. Greene

For the past two years, Tenneco Minerals Company has been evaluating a refractory, pyritic, carbonaceous gold deposit, Results from agitated biological oxidation reactor tests show the gold extraction was increased from 15 to 90 percent using microbial oxidation, Also, no preg robbing occurred after complete microbial oxidation. Three column biological oxidation tests were then initiated on minus 1/2 inch ore. Biological oxidation was discontinued in two of the three tests, These columns then were leached with cyanide. The maximum gold recovery was 62 percent. No preg robbing was observed,

Jan 1, 1990