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Copper Chalcocite Derimming of Pyrite with Cyanide

Many of the major copper ore bodies throughout the world contain chalcocite (79.9% Cu) as the principal copper mineral, yet the grades of copper concentrates produced from these ores rarely exceeds 25 to 28% Cu and in one known instance went as low as 13%. The low grade has traditionally been attributed to the presence of “activated pyrite” and/or chalcopyrite, and the universal approach has been excessive regrinding with all of its inherent effects-high capital, energy and maintenance costs, excessive sliming, and concentrate filtration difficulties (high moisture content).

Rimmed pyrite particles at a minus 65 mesh grind are usually observed in two forms:

cyanide-single-rim-of-chalcocite

In many instances, these rims are one micron or less, with mono or dimolecular films being invisible at 400 to 600 magnification. Thus, the rims responsible for major lowering of grade represent a very small fraction of the total copper content (1 to 3%).

Summary of American Cyanamid Investigations

Rougher concentrates from several major copper mills were examined under the microscope. In most cases pyrite rimmed with varying thicknesses of copper sulfides was present. Assay-size analyses of the rougher concentrates were made and theoretical surface areas calculated. On the average, the

How to Select the best Ultrafine Grinding Equipment

Equipment choices for ultrafine grinding encompass several different types of dry and wet size-reduction devices. These need to be put into functional perspective for systematic analysis of capabilities and limitations versus processing requirements of the materials to be satisfactorily ground.

Energy requirements for dry or wet grinding do not differ substantially when using suitable equipment and operating procedures. They are roughly proportional to the surface areas, as indicated on the second corresponding scale.

Consequently, the principal reasons for equipment choices lie elsewhere. The primary constraints are the particle sizes of the available feedstocks, the desired products and the dry or wet state of each. Common secondary constraints are existing equipment, if usable, and new equipment prices.

Dry Grinding Methods

Starting with moderately coarse material, three basic types of actions are employed to grind on down into the ultrafine range. In sequence, they are pressure-crushing, mechanical-impact and direct particle-attrition at velocities exceeding 300 fps.

In-process classification, used with pressure-crushing devices for dry materials, is not difficult down to 10 µm average particle size. At about this point, the possible contacts between particles begin to exceed 6 million/inch² and the grinding action will become limited by particle re compaction problems.

Wet Grinding Methods

All production type wet grinding equipment,

Titanium & Hydrometallurgy

Titanium’s performance characteristics in acidic oxidizing and mildly reducing environments make it applicable to numerous currently defined and many projected hydrometallurgical applications. With titanium’s current and projected availability and price stability increased use in pressure leach, piping systems and electrorefining is practical.

Titanium has a low density, .163 lb. per cubic inch, versus iron, as a guideline, of .281 lb. per cubic inch. Titanium’s tensile and yield strength properties are comparable to stainless steel. ASTM Grade 2 minimum 40 ski yield and 50 ksi tensile.

As the designating term implies, the commercially pure or unalloyed Grades are just that. They are minimum 98.5% titanium. Alloys 7, 9, and 12 are also relatively low in elemental metal additives. This lack of alloying constituents makes titanium resist volatile price changes due to shortages or price fluctuations of alloying additives such as nickel, manganese, chromium, molybdenum, cobalt, etc., used in stainless or high alloy steels. In the coming years this will have a significant effect on titanium’s competitive cost effectiveness.

Titanium’s resistance is further inhibited by oxidizing metallic ions in H2SO4 and HCl solutions. The corrosion resistance is based upon a closely knit oxide film formed on the surface and persists as long as the oxide film

Critical Surface Tension of Wetting of Sulfide Minerals

The critical surface tension of wetting (vc) of Cu2S, FeS2, PbS, and M0S2 were determined by plotting flotation recovery versus γLV which was arranged by methanol, and extrapolating to % R = 0.

γc values ranged from 26 dyne cm-¹ for M0S2 to 49 dyne cm-¹ for PbS and elemental sulfur gave a value of 31.5 dyne cm-¹.

It has, on the other hand, been customary to correlate contact angle (θ) with flotation data, although it is recognized that surface inhomogeneities and related contact angle hysteresis limit the interpretations pertaining to solid surface structures purely based on contact angle measurements. It is nonethless true that θ=0, when the liquid is water, corresponds to a hydrophilic solid.

Molybdenite (M0S2), pyrite (FeS2), chalcopyrite (CuFeS2), chalcocite (Cu2S), and galena (PbS) were hand-sorted from massive samples and ground by mortar and pestle, and the -100 mesh fraction used in experiments.

Curves obtained by the same method for the minerals Cu2S, PbS, CuFeS2, and FeS2 are given in Figure 2, where it is seen that for Cu2S and PbS, the extrapolation to % R = 0 produces γC value of 36 and 49 dynes/cm, respectively. FeS2 and CuFeS2 on the other hand, give curves which do not permit such

Effect & Influence of Flocculants & Surfactants on Filtration of Iron Ore Concentrate Slurry

Experiments were conducted with the addition of several types of flocculants and surfactants. The filtration response of the slurries was studied in terms of the cake formation rate and the residual cake moisture. An analysis of the results is presented in ascertaining the role of flocculants and surfactants during filtration

A specular hematite concentrate (67% Fe, 0.5% SiO2) wet ground to desired fineness was used as a standard sample in all the experiments. The isoelectric point of the sample was found to be at pH 6.3 by conducting electrophoretic measurements.

Test slurry samples were prepared by dispersing the required amount of moist solids in distilled water and then adding the flocculant and surfactant while mixing. The slurry was poured into the filter unit and the desired vacuum was applied. The time period required for water to disappear from the cake surface was recorded as form time. The vacuum application was continued until the cake dewatering ceased. Cake thickness was measured and a round sample was cut out by means of a thin-walled pipe for moisture determination. Cake moisture is reported on wet weight basis.

Experimental Results and Discussion

The volume of the sediment at the completion of settling gives a measure

Mineral Processing Circuit Simulator

The fundamental design philosophy was based on meeting three criteria: flexibility, modifiability and usability. Flexibility refers to the ease of using the simulator to study a variety of flowsheets. A stream and unit operation numbering scheme was developed as a means of meeting this requirement. This scheme, in conjunction with modularized unit operation programs, made it possible to simulate various unit operations in almost any sequence. Modularity, along with the use of a structured design approach, was also responsible for achieving the second requirement, modifiability. This design approach made the incorporation of new modules a relatively easy task. Finally, usability was achieved through the use of an interactive design providing a self-guiding, self-documenting environment for the user.

Flowsheet Specifications

The primary feature of a general-purpose flow-sheet simulator is its ability to simulate a variety of flowsheet configurations without requiring changes in the program code. This feature necessitates a means of specifying the simulation order for the various unit operations and a scheme for labeling stream flows in the flowsheet. The UCMINPRO provides the general purpose by dividing the plant flowsheet into a number of circuit, each circuit in turn containing the necessary unit operations.

Within the simulator, it was necessary

Selective Flocculant Design

The possibility of mineral beneficiation utilizing selective flocculation techniques has attracted considerable attention in recent years. This attention has resulted in the examination of numerous potential applications but unfortunately up to this time the great majority of reported separations have been achieved at bench level and there are no recently developed demonstrations of the technique on a commercial scale.

The Nature of Selectivity

The observed selectivity of polymer adsorption arises from the affinity of polymeric groups towards mineral sites and indifference towards others. Thus, conceptually such groups can be used both for recognition of, and binding to minerals. In order to achieve selective polymer adsorption, the correct chemical information has to be stored in the polymer groups and read out by mineral species.

It is absolutely critical to identify precisely the nature of the elements which contribute to polymer adsorption. Any inaccuracy or confusion in this regard has the following potential implications:

  1. Formulation of incorrect generalizations.
  2. Optimization may occur in a largely unpredictable manner.
  3. Success of secondary applications is not assured.

Design Strategies

Selective flocculation exploits differences in the surface chemical properties of minerals and hence design of suitable systems necessitates controlling the polymer-mineral recognition process via the complementary chemical information

Rubber Lined Balling Drums in Pelletizing Plant

The balling section of the pelletizing plant at Hoogovens Ijmuiden consists of 7 balling drums. Each with an average capacity of 100 tons of green pellets per hour.

In view of these results it was decided to equip one drum at the Hoogovens’ plant with a rubber-lining although of a slightly different construction.

General Plant Description

The pelletizing plant (capacity 3.3 mln tons/ yr) operates on a variable mixture of 6 to 10 widely different ores. A bedding system ensures that during about 1 week a constant and homogenized ore mixture is fed to the plant.

The ore mixture is dry grinded by means of 3 ball-mills (4.2 x 10.5 m) operating in closed circuit. Drying takes place inside the mills. The ground concentrate is stocked in 3 areated storage bins with a storage capacity of about 24 hours.

Rewetting takes place in 3 Lodige-mixers. Simultaneously the required amount of bentonite (~ 0.5 %) is added.

Description of the Rubber-Lined Drum

To the inner wall of the test drum 7 pieces conveyor-belt have been fixed by means of metal strips over the full length of the drum. Also the middle of the conveyor-belt pieces are fixed to the wall, making a total of

Preventive Maintenance & Vibration Analysis

The massive complexity of the systems dictated that we establish a computerized preventive maintenance program as expansion occurred since the timely performance of routine maintenance functions was rapidly exceeding any manual method of job scheduling. Each component of the system was analyzed by experienced personnel. A frequency interval was established based on anticipated usage. This could be based on hours operated, tonnage handled, or some other measurable element. This, then, established the WHEN portion of the program. The WHEN had to be meshed with the availability of existing maintenance forces in our various shops, which include a fully equipped machine shop, centralized steel fabrication shop and decentralized structural repair gangs, a mobile equipment repair facility, a centralized electric motor maintenance shop plus electricians assigned to operating crews, and a construction department which includes plumbers and other crafts to maintain all support facilities. This combination of available forces and job frequency, after melding, became the WHAT-WHEN portion of the program.

One week in advance of the scheduled work week, the computer prints out a list of all maintenance jobs to be performed. The print-outs, which include the standard manhours to perform each job, are routed to the Supervisor of Maintenance Control, who

Rotating Probability Screens for Steam Coal Preparation

The purpose of preparing steam coal is to remove high-gravity impurities which have low heating value and would burden the ash handling system in the power plants if they are not removed. In the preparation process, water is used either to form a heavy medium suspension, or to act as a pulsating stream to stratify the coal bed. In both applications, clean coal and refuse will be separated after emerging from the water medium. The moisture contents of the products, refuse and clean coal, should be as low as possible.

The traditional method of removing fine coal such as ¼” x 0 from overall 4″ x 0 raw coal is to use a vibrating screen at about 900 RPM. However, since the advent of the continuous and long wall mining methods, more water is required to suppress dust at the mine face. As a result, the raw coal contains surface moisture exceeding 4% or 5%, which makes the screening difficult. The enlarging of screen openings to 3/8″ or to ½” only helps the dry screening of wet coal to a degree, but this does not solve the screen blinding problems.

Currently an Illinois coal producer is marketing 2″ x 0 raw coal

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