Mineral Processing Engineering

Grinding Mill Design & Ball Mill Manufacturer

All Grinding Mill & Ball Mill Manufacturers understand the object of the grinding process is a mechanical reduction in size of crushable material. Grinding can be undertaken in many ways. The most common way for high capacity industrial purposes is to use a tumbling charge of grinding media in a rotating cylinder or drum. The fragmentation of the material in that charge occurs through pressure, impact, and abrasion.

Grinding is converting energy: When the grinding charge is forced to tumble the motor energy is converted into new particle surface and heat.

An important point for the economy is that the size of the grinding media suits the material to be ground.

The choice of mill design depends on the particle size distribution in the feed and in the product wanted. Often the grinding is more economic when executed in a primary step, followed by a secondary step, giving a fine size product.

As experts in crushing and grinding – can offer a full range of grinding mill types and sizes. Our mills are identified by codes of letters:

C=central trunnion discharge
P=peripheral discharge
R=spherical roller trunnion bearing, feed end
H=hydrostatic shoe bearing, feed end
R=spherical roller trunnion bearing, discharge end
K=ring gear and pinion drive


By | 2017-08-17T08:39:51+00:00 February 20th, 2017|Categories: Crushing & Screening|Comments Off on Grinding Mill Design & Ball Mill Manufacturer

Tungsten & Gold Recovery Scheelite Ores

Investigations were conducted by the U.S. Bureau of Mines to develop flowsheets for the recovery of tungsten and gold from four Alaskan scheelite-bearing ores. Basic gravity concentration and cyanide leach tests were performed on all samples. About 46 pct of the tungsten and 30 pct of the gold from one sample were recovered in a gravity concentrate containing 24 pct WO3 (tungstic oxide) and 119 troy ounces per short ton (tr oz/st) Au. Froth flotation of the gravity concentrate resulted in separate tungsten and gold products with grades of 38 pct WO3 and 2,720 tr oz/st Au and recoveries of 60 and 97 pct, respectively. Additional gold was recovered from the gravity and flotation tailings by cyanidation. Overall recoveries of tungsten and gold from this sample were 28 and 94 pct, respectively.

A flowsheet with mill design parameters was developed that consisted of (1) free gold and scheelite recovery by gravity methods and froth flotation and (2) fine-grained gold recovery by cyanide leaching of reground gravity and flotation tailings, followed by a carbon-in-pulp (CIP) circuit. Data were developed from the Bond mill work index, gold and tungsten flotation, conventional and high-rate thickening, cyanide leaching, and CIP adsorption tests.

The United States is

By | 2017-11-21T15:51:21+00:00 November 21st, 2017|Categories: Flotation, Gravity Concentration, Hydrometallurgy|Tags: |Comments Off on Tungsten & Gold Recovery Scheelite Ores

Synthetic & Substitute Cupola

We evaluated synthetic fluorspar as a substitute for natural fluorspar flux in basic cupola ironmaking. The synthetic fluorspars tested were prepared from waste fluosilicic acid generated during the processing of fluorapatite ore. The cupola trials showed the synthetic products to be the equivalent of natural fluorspar from an operational standpoint. However, wet scrubber sampling showed that substantial losses of volatilized fluorine occurred from the cupola during operation. The losses during synthetic fluorspar trials considerably exceeded those from natural fluorspar trials. Laboratory viscosity testing, using a high-temperature rotational viscometer, confirmed this finding and indicated that fluorspar volatility in slags is related to slag basicity. Synthetic fluorspar is accordingly recommended more for highly basic cupola operation (>1.3 basicity) than for neutral or acid operation, because of the increased potential for pollution and baghouse filter deterioration.

This research is a continuation of work on synthetic fluorspars applied as a flux for iron and steelmaking operations. This report covers synthetic fluorspar testing in cupola ironmaking operations and concludes the Bureau of Mines research on the metallurgical application of this material.

Fluorspar (CaF2) is the predominant auxiliary flux employed in U.S. ironmelting and steelmaking operations. It is of concern to the Bureau of Mines because of its

By | 2017-11-21T15:49:59+00:00 November 21st, 2017|Categories: Smelting - Melting - Refining, Uncategorized|Tags: |Comments Off on Synthetic & Substitute Cupola

Recycle Superalloy Scrap Metals

We treated mixed and contaminated superalloy scrap by pyrometallurgical and hydrometallurgical methods to separate and recover metal values. Best results were obtained by leaching Zn-treated or atomized scrap with HCl-O2 at 95° C and 50 psig O2. This resulted in dissolving approximately 98% of the Al, Co, Cr, Cu, Fe, Mn, Ni, and Zn while rejecting over 98% of the Mo, Nb, Ta, Ti, W, and Zr as an insoluble refractory residue. Chlorine was successfully substituted for HCl to leach Zn-treated scrap but was unsuccessful for leaching atomized scrap. The leaching solution was treated by pH adjustment and hydrothermal precipitation at 200° C for 4 h to remove Al, Cr, Fe, and other contaminants as a filterable precipitate. Recovery of Co and Ni would be accomplished by solvent extraction and electrowinning. Chromium recovery as a ferroalloy was demonstrated.

The Bureau of Mines is investigating techniques to recycle contaminated bulk superalloy scrap by sequential pyrometallurgical and hydrometallurgical methods. Cobalt- and nickel-based superalloys have critical applications in the aerospace and power-generation industries; they are used in turbines and other high-temperature equipment that require oxidation resistance and high strength at elevated temperatures. The United States must import a large percentage of the metals that

By | 2017-11-20T16:44:27+00:00 November 20th, 2017|Categories: Hydrometallurgy, Pyrometallurgy|Tags: |Comments Off on Recycle Superalloy Scrap Metals

Recover Nickel, Cobalt, Molybdenum & Tungsten Hydroprocessing Catalysts Waste

We investigated anhydrous chlorination and caustic-acid leaching processes to recover Ni, Co, Mo, and W from waste hydroprocessing catalysts. In batch laboratory-scale equipment, the chlorination process extracted 61 to 99 pct of the metals. Final recovery was 65 to 99 pct. The caustic-acid leaching process extracted 81 to 98 pct of the metals. Final recovery was 36 to 99 pct. Chlorination processing included roasting, chlorination, hydrolysis of metal chlorides for recovering Mo or W, water leaching of Ni or Co from the spent charge, purification, and solvent extraction or precipitation of Ni or Co from the purified solutions. Caustic-acid leach processing included NaOH leaching, solvent extraction of Mo or W from the NaOH leach liquor, H2SO4 leaching of the NaOH leach residue, purification, and solvent extraction or precipitation of Ni or Co from the purified solution.

An objective of the U.S. Bureau of Mines is to provide the technology that will help to assure an adequate supply of critical metals for the United States. This objective requires meeting U.S. economic and strategic needs and reducing or avoiding total U.S. dependence on foreign supplies. Achieving these goals necessitates evaluation of the potential recovery of metals from secondary sources as well as from

By | 2017-11-20T16:52:51+00:00 November 20th, 2017|Categories: Hydrometallurgy|Tags: |Comments Off on Recover Nickel, Cobalt, Molybdenum & Tungsten Hydroprocessing Catalysts Waste

Plumbojarosite – Recovering Lead & Silver

We investigated a hydrothermal sulfidation (HTS) and chloride leaching procedure to recover lead and silver from plumbojarosite. The plumbojarosite, generated during pressure-oxidative leaching of zinc concentrate in a commercial operation, contained, in percent, 25.4 Pb, 18.8 Fe, 1.4 Zn, 29.5 sulfate (SO4²-), 3.2 elemental sulfur (S°), 13.4 total S, and 7.4 tr oz/st Ag. The HTS was conducted in an autoclave and converted the plumbojarosite into amorphous iron oxide and liberated the Pb and Ag as sulfides (S²). The best operating conditions were 50 g of plumbojarosite and 7 pct S° (2.04 g S° added) in 500 ml of 2.0-mol/L NH3 at 150° C for 1 h. The sulfidation product contained, in percent, 37 Pb, 28 Fe, 2 SO4²-, 7 total S, and 11.2 tr oz/st Ag. Flotation of the sulfidation product was conducted at pH 3 with 15-pct pulp density and 2.4 lb/st of isopropyl xanthate as collector. The flotation concentrate contained 43 pct Pb, 25 pct Fe, and 13 tr oz/st Ag. FeCl3 leaching of the sulfidation product in a resin kettle extracted 98 pct Pb and 97 pct Ag from the suifidation product, and HCl-O2 leaching in a shaker glass bottle extracted 99 pct Pb and 98

By | 2017-11-19T14:45:12+00:00 November 19th, 2017|Categories: Hydrometallurgy|Tags: |Comments Off on Plumbojarosite – Recovering Lead & Silver

Grinding Media Corrosion

We determined the effect of common sulfide minerals on the corrosion rates of various types of ferrous alloy grinding media. Data obtained from this study will aid in determining the contribution of any electrochemical reactions between sulfide minerals and grinding media to the total grinding media consumption. Common sulfide minerals used in this study were chalcopyrite, galena, and sphalerite. In the presence of oxygen, chalcopyrite was found to increase the corrosion rate, galena was found to decrease the corrosion rate, and the effect of sphalerite was dependent upon the type of grinding media. Possible electrochemical reactions of these minerals in the presence of grinding media are suggested.

Grinding requires a large capital investment for the minerals processing industry and frequently is the area of maximum use of power and wear-resistant materials. A typical copper producer processing 27,000 st/d of ore, may spend $25,000 per day for replacement of grinding balls. A National Academy of Sciences report estimates that the domestic copper industry consumed 205,000 st of grinding balls in 1978.

Total wear of grinding media is due to corrosion, mechanical wear, and interaction between corrosion and wear. The contributions and interactions of these processes are poorly understood, and much disagreement exists in

By | 2017-11-19T14:48:09+00:00 November 19th, 2017|Categories: Grinding|Tags: |Comments Off on Grinding Media Corrosion

Natural Flake Graphite & Carbon Fiber VS Dolomite-Carbon Refractories

We investigated the role of imported natural flake graphites in dolomite-carbon refractories used in steelmaking processes and evaluated carbon fibers as a potential substitute. Varying quantities (1.5-30 pct) of natural flake graphite and carbon fibers were added to test samples. The effect of the additions on modulus of rupture (75°-2,750° F), deformation under load (2,750° F), and air-slag-metal resistance (3,000° F) was studied.

Carbon purity of natural flake graphite additions did not influence hot strength, deformation under load, or air-slag-metal resistance. When the quantity of 90-pct-carbon graphite addition varied between 0 and 30 wt pct, hot strength was highest, deformation under load lowest, and air-slag-metal wear the least at 10 wt pct. As test temperature increased from 500° to 2,750° F, the hot strength difference became less.

Carbon fiber additions were limited to 1.5 pct in dolomite-carbon brick. At this level, physical properties were generally comparable to those obtained with natural flake graphite, but were below values obtained with 10-pct-flake graphite additions. Carbon fibers are not considered a satisfactory substitute for natural flake graphite.

Continuous casting of steel combined with increased operating temperatures and demands for longer refractory life have focused attention on carbon-containing refractories. Carbon, in the form of natural flake graphite,

By | 2017-11-19T14:51:29+00:00 November 19th, 2017|Categories: Smelting - Melting - Refining|Tags: |Comments Off on Natural Flake Graphite & Carbon Fiber VS Dolomite-Carbon Refractories

How Metal Impurities Affect Gold Adsorption on Activated Carbon in Cyanide Solutions

We performed batch equilibrium contact experiments to examine the ability of activated coconut-shell carbon to adsorb various metal cyanide complexes. Tests were also conducted to determine the effect these cyanide complex impurities might have on the adsorption of gold by the activated carbon. Metal cyanide species included in the investigation were antimony, arsenic, cadmium, calcium, cobalt, gold, iron, mercury, nickel, silver, thallium, and zinc. Tests were made over a pH range of 6.4 to 12.5.

The carbon exhibited a preference for gold adsorption over other metals present in solution. In the absence of gold, the metal cyanide complexes were adsorbed; adsorption generally decreased with increasing pH. However, calcium and thallium adsorptions increased with increasing pH, while arsenic and iron were not adsorbed at any pH.

The use of activated carbon for the recovery of gold and silver from dilute caustic cyanide solutions has been well documented in recent years. Whether employed in carbon-in-pulp, carbon-in-leach, or loading-column processes, activated carbon has amply demonstrated its ability as an efficient extractor of precious metals from cyanide leach solutions.

With the discovery and treatment of disseminated gold deposits in the Western United States and in the Republic of South Africa, many complex ore deposits are being leached

By | 2017-11-19T14:53:50+00:00 November 18th, 2017|Categories: Hydrometallurgy, Precious Metals, Smelting - Melting - Refining|Tags: |Comments Off on How Metal Impurities Affect Gold Adsorption on Activated Carbon in Cyanide Solutions

Procedure to Determine Helium in Water

We have developed an improved method for determining dissolved helium in water in the concentration range of 4.0 x 10 -8 to 270 x 10 -8 cm³ He (STP)/cm³ H2O. The method is a modification of a previously reported method that was developed for analyzing surface and subsurface waters in geochemical survey work. Water samples are collected in 500-cm³ stainless steel cylinders, and the dissolved gases in a sample are extracted into an evacuated cylinder of equal volume. After addition of 30 psig of nitrogen containing less than 2 ppb helium to the extracted gases, the resulting mixture is analyzed for helium using a helium-tuned mass spectrometer. The helium content of the water sample is determined from an empirical calibration that is established by analyzing standard solutions of helium in water. The accuracy of the method is ±7 pct for helium-in-water concentrations above 10 x 10 -8 cm³ He (STP)/cm³ H2O.

The U.S. Bureau of Mines has published the results of reconnaissance geochemical helium² surveys that were conducted in the vicinity of the Bush Dome helium storage reservoir in the Cliffside Gasfield. The surveys revealed that some of the ground waters were anomalously “high” in dissolved helium. The anomalous helium-in-water concentrations

By | 2017-11-19T08:04:08+00:00 November 18th, 2017|Categories: Assaying|Tags: |Comments Off on Procedure to Determine Helium in Water

Recover Sulfide Concentrate Tailings by Flotation

The Missouri Pb ores are the only domestic Co resource being mined and processed for other metals; therefore, they present a viable short-term opportunity for Co production. Lead, zinc, and copper concentrates are produced from the ore. The Cu concentrate can contain up to 30 pct Co and the Pb concentrate up to 15 pct Co. Since Co is detrimental to the processing of the Zn concentrate; the remainder of the Co is rejected to the tailings. The tailings can contain as much as 50 pct Co originally present in the mined ore. Researchers at the U.S. Bureau of Mines have successfully tested on a continuous basis a process that recovers a bulk sulfide concentrate from mill tailings. The concentrate contains up to one-half of the Co and from 50 to 90 pct of the Pb, Zn, and Cu. Concentrate weight represents 10 pct or less of the total tailings.

The United States is dependent on foreign sources for virtually all of its Co. There are domestic occurrences of Co in Alaska, California, Minnesota, Idaho, and Missouri. These deposits are subeconomic regarding the Co values, and the only deposits that are being actively mined are the ores of the Missouri Lead

By | 2017-11-19T07:53:44+00:00 November 18th, 2017|Categories: Flotation|Tags: |Comments Off on Recover Sulfide Concentrate Tailings by Flotation

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