About David

Since 1993, when he obtained his Mining Engineering Degree from Queen’s University, David has acquired experience in operating roles including many years in post-commissioning operations troubleshooting. Mineral Processing and Metallurgy has become a core strength and passion for Mr. Michaud. Learn more at

Claw Hammer Scaling Tool

Proper scaling is necessary for safe operation during any underground mining activity. This need is documented in the mandatory regulations for scaling found in 30 CFR 57. In many U.S. mines operating today, scaling is accomplished by manually barring-down the loose material from around the mine opening. Barring-down requires a great deal of physical strength, endurance, and judgment to safely scale an underground opening. In addition to being one of the most physically demanding activities underground, it is one of the most dangerous. As recent accident statistics indicate, a large percentage of the “fall of ground” accidents and fatalities is directly related to manual scaling. Consequently, safer scaling practices are needed within the mining industry.

In addition to the definite safety hazard, adverse economic factors are also associated with manual scaling. Lost-time accidents and fatalities represent a significant direct cost in terms of the loss of skilled miners and a more indirect cost in terms of increased premiums on Workman’s Compensation insurance. Despite the recent trend toward mechanization in underground mining systems, scaling remains primarily a manual operation. Further, it can be a very time- and labor-consuming process. Hence, as labor costs increase, the cost of scaling using current practice will

Wire Ropes & Mine Hoisting

Although wire rope has been in use for over 100 years, it is a complex structure that is still not well understood. Wire ropes are made in diameters from less than 1/32 to more than 7 in and can have as many as 900 individual wires. The mining industry uses a lot of wire rope, not only for hoists for shafts and slopes, but also for elevators, cranes, draglines, and haulage cables. This report is limited to a discussion of the kinds of wire ropes used for hoists in coal mines and in metal-nonmetal mines.

Wire rope consists of three basic components; while few in number, the components may vary in both complexity and configuration to produce ropes for a specific purpose or characteristic. The three basic components of a standard wire rope design are (1) wire that forms the strand, (2) multiwire strands laid helically around a core, and (3) the core (fig. 1).

Wire for rope is made in several materials and types, such as steel, iron, stainless steel, morel, and bronze. By far, the most widely used material is high-carbon steel. This is available in a variety of grades, each of which has properties related to the basic curve

Biological Leaching of Manganese Ores

Biological leaching of low-grade ores has been gaining interest and acceptability in recent years. Sulfide ores, which are subject to oxidation of specific bacteria such as Thiobacilli, are being bioleached commercially. Other ore types, especially oxides and silicates, have been examined for their leachability by microorganisms. Ehrlich (1980), Holden and Madgwick (1983), Groudev (1987), and Bosecker (1989) have described some of these studies.

The Bureau of Mines (Perkins and Novielii, 1962) showed that manganese could be leached from several types of domestic ores by bacterial action. More recent studies on the bioleaching of manganese ores have focused on oxide ores, in particular ores in which the primary oxide MnO2 is reductively solubilized by the action of heterotrophic microorganisms. Manganese bioleaching studies have been reported by Madgwick (1987), Ehrlich (1987), Gupta and Ehrlich (1989), Agate and Deshpande (1977), and Groudev (1987). Hart and Madgwick (1986) reported that leaching of the Australian Groote Eylandt ore occurred by bioreduction under microaerobic (lower than atmospheric levels of free oxygen available) conditions when molasses was used as the nutrient source.

Microorganisms capable of solubilizing manganese bioreduction include Achromobacter spp., Bacillus spp., Enterobacter spp. and Aspergillus niger as reported by Ehrlich ( 1980) and Silverio and Madgwick (1985).

How to Make Lead Metal by Molten Salt Electrolysis

Molten-salt electrolysis of lead chloride is an integral unit operation in a ferric chloride leaching process that was developed by the U.S. Bureau of Mines for treating galena concentrates as an alternative to smelting. Prior to the Bureau’s work, several other investigators had studied molten-salt electrolysis of lead chloride. As part of the Bureau’s research effort, several monopolar and bipolar electrode designs were investigated in bench-scale electrolytic cells, which ranged in capacity from 5 to 400 A. The Bureau also built and operated a 3,000-A lead electrowinning cell that was tested at 450° C with a LiCl-KCl-PbCl2 electrolyte as part of an integrated, semi-continuous operation of the process. The 3,000-A (fig. 1) cell used horizontal graphite plate electrodes and was capable of producing 225 kg of lead metal per day. The anode consisted of two graphite plates 37 by 61 by 7.6 cm thick. The bottom surfaces of the anode plate were grooved with six 0.95-cm-wide channels which were sloped at 4° from the horizontal to direct chlorine gas away from the anode surface. The cathode was a single graphite plate measuring 74 by 61 by 5.1 cm thick. The cathode had six 0.64-cm wide grooves slanted to direct the

Recover Anhydrous ZnCl2 from Aqueous Solutions

At the present time, zinc is produced commercially by a roast-leach zinc electrowinning process. The primary source is high-grade concentrates of the mineral ZnS. Concentrates must contain low levels of iron to avoid formation of zinc ferrites during roasting because zinc ferrites are not amenable to leaching and cause decreased zinc recovery. Also, SO2 is produced during roasting and must be scrubbed from flue gases to prevent air pollution. Progressively more stringent standards for SO2 emission and interest in processing more complex sulfide deposits have prompted research to develop hydrometallurgical processes as alternatives to the conventional roast-leach treatment of ZnS concentrates. Most complex sulfides are lower grade, contain more impurities, and are not amenable to treatment by existing techniques.

One method that shows promise is chlorine-oxygen leaching. This method is particularly well suited to treating ores that are high in iron content and yields a concentrated ZnCl2 solution. Metallic zinc may be recovered from the solution by electrowinning; however, it is of unsatisfactory quality. There are no known techniques for producing a satisfactory zinc plate from chloride solutions. As an alternative, a molten-zinc product can be produced by molten-salt electrolysis of anhydrous ZnCl2.

Molten-salt electrolysis of ZnCl2 yields a molten-zinc product, which

Solvent Extraction – Predicting Equilibrium Values

Trends in extractive metallurgy in recent years from milling and smelting of high-grade ores toward heap leaching and electrowinning of low-grade or marginal ores, have resulted in increased reliance on solvent extraction as a key part of profitable operations. Consequently, solvent extraction processes and reagents have been extensively studied, resulting in greatly improved techniques and extractants. Solvent extraction modeling, which predicts extraction under various conditions, has been used as a tool by researchers and some industrial chemists to decrease the number of time consuming and laborious shake-out tests needed to produce data to operate effectively the extraction unit. Modeling of nickel extraction from ammoniacal solutions was the goal of this work.

Often-cited earlier modeling work centered on copper extraction from acidic solutions with chelating hydroxyoximes. A statistical model of copper-ammoniacal systems was developed by Valdes using very high concentrations of aqueous copper. Establishment of extraction mechanisms and development of appropriate equations for ammoniacal systems was done with copper and nickel by Cooper and Rice. The work of Cooper was in some ways similar to this report in that he predicted copper and nickel extraction using LIX 64N with only a 6-pct error. However, some important aspects were not considered or reported.

Recover Copper by Leaching Sulfidation-Partitioned Chalcopyrite

There are a number of important metals that exhibit a high affinity for S, forming sulfides in naturally occurring mineralization. Of these, several appear as complex sulfides such as CuFeS2, cobaltite (CoAsS), and pentlandite [(Fe,Ni)9S8]. Such complex minerals contain, in addition to the S and metals of value, one or more structurally bound metals of little interest for recovery. These extraneous metals must, however, be carried through conventional extractive processing because they are not directly removable.

Sulfidation partitioning of complex sulfides holds potential for improving the metal extraction technology of naturally occurring minerals as well as manmade secondary and byproduct materials. The basic research now in progress at the U.S. Bureau of Mines was designed to assess the feasibility of effectively partitioning complex sulfides into simpler individual sulfide phases by sulfidation reactions. When partitioned, such reaction products afford opportunity for selective extraction of the metals of value from the low-value constituents with fewer processing steps.

The present investigation involves the development of extractive procedures to selectively recover Cu from the sulfidation-partitioned complex mineral CuFeS2. With conventional technology, Cu is recovered from CuFeS2 concentrates by crushing, beneficiation concentration, roasting, and smelting techniques, followed by electrorefining and/or elcctrowinning operations. Sulfur-bearing gas emissions are generated

Recover Manganese – Fluosilicic Acid Leaching

Manganese serves two functions in the steelmaking process; it is an alloying agent improving such properties as strength, toughness and hardenability, and it is also used to control sulfur. Manganese controls sulfur by forming manganese sulfide instead of iron sulfide, which would make the steel brittle. The average manganese content for all types of steel is 8.7 lb/st or 0.44 pct. The United States has no high-grade manganese deposits (containing 35 pct or more manganese) and no economical methods of recovering manganese from its low-grade deposits exist. Consequently, there is no domestic production of manganese, and the United States is completely dependent upon foreign sources for manganese.

In 1987, the United States imported 340,000 st of manganese ore, 360,000 st of ferromanganese and 191,000 st of silicomanganese to produce 89.3 million st of steel. The principal sources of high-grade manganese imports are the USSR, Republic of South Africa, Brazil, and Gabon. The United States will continue to be dependent upon world resources unless domestic resources can be utilized. One such domestic manganese resource is BOF steelmaking slap.

The trend in iron and steel production is away from the older, less efficient open-hearth furnaces to the BOF furnace. Currently, about 60 pct of

Multi-timbered Wood Crib Supports

Wood cribs are used extensively by the coal mining industry in a variety of applications to stabilize mine openings. The U.S. Bureau of Mines is conducting research to evaluate the load-displacement characteristics of active and passive mine roof support systems, such as wood cribbing, so that the selection and design of these supports are compatible with the conditions in which they are employed.

A cooperative effort was undertaken by the U.S. Bureau of Mines with the Cape Breton Development Corp. (CBDC) Sydney, Nova Scotia and the Cape Breton Coal Research Laboratory (CBCRL), Sydney, Nova Scotia to evaluate the behavior of gate side packing materials used in advancing longwall mining applications in the Sydney Coalfield. As part of this effort, full-scale tests were conducted on wood pack wall supports in the Bureau’s 3-million lb (13.3 MN) active load frame. Gate roads constructed behind an advancing longwall face are supported on one side by a continuous coal pillar and on the side nearest the extracted panel by some form of artificial support, typically referred to as the gate side pack wall. In addition to providing resistance to gate road convergence to maintain entry stability, the gate side pack must also serve as a

Biosorption of Metal Contaminants Using Immobilized Biomass

The removal of toxic metal contaminants from aqueous waste streams is one of the most important environmental issues facing the United States today. Although this issue has been addressed for many years, effective treatment options are limited. Chemical precipitation, ion exchange, reverse osmosis, and solvent extraction are the most commonly used procedures for removing metal ions from dilute aqueous streams. However, these procedures have significant disadvantages, such as incomplete metal removal, high reagent or energy requirements, and generation of toxic sludge or other waste products that require disposal. These disadvantages are particularly apparent at the low metal concentrations often encountered in waste waters.

The search for new and innovative treatment technologies has focused attention on the metal-binding capacities of biological materials. Peat moss, yeast, algae, bacteria, and various aquatic floras have been identified as organisms capable of sorbing toxic and heavy metals from dilute aqueous solutions. The mechanisms associated with metal sorption by biological materials are complex and involve both extracellular and intracellular metal binding. Extracellular metal accumulation has been reported as the more rapid mechanism and likely has the more significant role in metal sorption from waste waters.

Although living microbial populations are effective sorbents for toxic and heavy metals, available

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