Mineral Processing Engineering

LIX-64N A Progress Report on the Liquid Ion Exchange of Copper

In late 1965 General Mills announced the availability of a new liquid ion exchange reagent LIX-64, for the recovery of copper from various solutions, such as dump leach liquors. Acceptance of this material by the copper industry has been gratifying. A number of pilot plants have been operated, and at this writing there are four commercial plants either in operation or under construction. The properties and operating characteristics of this reagent have been described previous papers.

Chemistry of LIX-64N

As with LIX-64, LIX-64N operates on a hydrogen ion cycle:


(2RH)ORG + (Cu++ + SO4 =)AQ (R2Cu)ORG + (2H+ + SO4 = )AQ


(R2 Cu)ORG + (2H+ + SO4 =)AQ (2RH)ORG + (Cu++ + SO4 =)AQ

Chemically, the two reagents perform similarly, except LIX-64N operates either in an extended pH range or will perform the same task in a reduced number of stages.

Laboratory Investigations

A pilot circuit was assembled in the laboratory, consisting of four extraction stages, three strip stages, and a small electrowinning cell. This circuit was operated with both LIX-64 and LIX-64N under conditions as closely identical as possible for comparison purposes. A number of typical acid liquors (obtained from actual southwestern copper operations) were used as feed solutions. These liquors

By |2019-06-24T17:30:09-04:00June 24th, 2019|Categories: Hydrometallurgy|Tags: |Comments Off on LIX-64N A Progress Report on the Liquid Ion Exchange of Copper

Limestone Treatment of Acid Mine Drainage

The occurrence of acid mine drainage (AMD) with coal mining has been well documented. Less documentation is available of its association with other types of mining, e.g., copper, gold, zinc, and sulfur. Yet there are many locations in the western states where acid mine drainage is as great a pollution problem as in Appalachia and in some cases, because of the high copper, zinc, and arsenic concentrations, they present an even more difficult problem.

Until a few years ago, it was generally believed that the neutralization of acid mine drainage was uneconomical thus, AMD was allowed to discharge freely into our streams. However, the demand for good water finally dictated that the mining industry be included under pollution laws. In 1964 the Commonwealth of Pennsylvania passed a law requiring that all active mine discharges meet a discharge standard of pH 6-9, iron less than 7 mg/l, and the water must have a net alkalinity. Several other states now require active mines to treat AMD.

In all but a few cases, lime neutralization, often in conjunction with aeration, has been the treatment method used. The high cost of lime as compared to limestone and the poor quality sludge, (slow settling, large volumes, and

By |2019-06-24T17:30:02-04:00June 23rd, 2019|Categories: Environment & Tailings|Tags: |Comments Off on Limestone Treatment of Acid Mine Drainage

Impermeable Dump Leaching Chemistry

A series of tests were run on fresh Becker drill samples from a drill hole in Kennecott’s Chino “J” dump, near Silver City, New Mexico, to obtain data on the leaching chemistry of a relatively impermeable sulfide copper waste dump. Vertical profiles were made of the moisture and soluble-salt content; the content of Fe+³, Fe+², Cu+², and H+ in the interstitial solutions; and the content (both total and non-water soluble) of iron, copper, and sulfur in the residues. Conclusions were drawn from these data concerning the leaching chemistry and hydrological nature of this dump.

This study was similar to a previous study conducted on other, more permeable leach dumps at Chino. Briefly, the conclusions of the first study are as follows:

  1. Solutions are transported through major portions of more-or-less permeable dumps at variable and rather slow flow rates according to the permeability of the strata. Some short-circuiting of solutions through the dump, however, is indicated.
  2. The oxidation and hydrolysis of iron-bearing solutions occurs in the upper 40 feet of these dumps. This phenomenon appears to be a result of bacterial, air, and ground-water oxidation of a near-surface zone of retained iron and copper salts. The cyclic addition of leach fluids and
By |2019-06-24T17:29:36-04:00June 23rd, 2019|Categories: Leaching|Tags: |Comments Off on Impermeable Dump Leaching Chemistry

Selection of a Leach Dump Test Area

Leaching of waste material at Kennecott’s Chino Mines Division at Santa Rita, New Mexico, has been accompanied by increasing difficulty in circulating leach solutions through the dumps. As a means of recognizing existing problems and considering alternative applications of the leaching concept, a leaching research program was proposed which could be applied to a specific, typical waste dump. Conclusions derived from the area could then be applied to other leaching areas at Chino.

Preliminary field data acquired through Becker drilling and logging determined the final configuration of facilities for a tritium tracer test which was conducted as a portion of the research program. The data have led to recognition of several leaching problems which were previously unknown, and which appear to be relatively common throughout Chino’s waste dumps. The data have also served as a positive basis for an evaluation of all testing designed to improve leaching and for decisions regarding future research goals and impact.

‘Chino’s J dump was selected as a leach dump test area for a leaching research program on the basis of four general characteristics:

  1. The initial copper content of J dump was high and the apparent copper recovery through leaching is low. The current copper grade averages
By |2019-06-24T17:25:25-04:00June 23rd, 2019|Categories: Leaching|Tags: |Comments Off on Selection of a Leach Dump Test Area

Laboratory Extraction of Copper from Chalcocite by Roasting Reduction and Smelting

In a broad sense, sulfide copper pyrometallurgy is a batch sequence in three separate vessels, i.e., reverberatory furnace to yield “matte copper,” a converter to produce “blister copper,” and another reverberatory furnace to produce fire-refined copper. Matte smelting is relatively unchanged since it became universal practice some 50 to 60 years ago. It is now serving wide range of smelter feed materials, but many concentrates ore not immediately amenable to the process. There may be an excess or deficiency of essential matte-forming, elements, so adjustments must be made to the furnace charge. When smelter feed carries a sufficient excess of sulfur, byproduct manufacturing of elemental sulfur or H2SO4, may be incorporated into the metallurgical flowsheet. At the other extreme, there arc abundant copper resources which lack sufficient sulfur and other elements to sustain the full chemistry involved in matte smelting. This necessitates adding sulfur to make the product fit the process, and usually none is recovered. From the standpoint of pollution alone, development of a smelting technique for low-sulfur concentrates not requiring the addition of sulfur would be a significant gain.

The Twin Cities Metallurgy Research Center has been engaged in a study to uncover a more direct pyrometallurgical process for

By |2019-06-24T17:26:22-04:00June 23rd, 2019|Categories: Leaching|Tags: |Comments Off on Laboratory Extraction of Copper from Chalcocite by Roasting Reduction and Smelting

Nonmagnetic Taconite Grindability – Influence of Reduction and Thermal Shock

Among the most important processes being developed for beneficiating nonmagnetic taconites is the reduction roasting-magnetic separation process. This process consists of first converting the nonmagnetic iron oxides of the ore to a magnetic form at an elevated temperature in a reducing atmosphere, after which the ore is concentrated by conventional magnetic separation methods. Of particular interest to the overall economics of this process is the reduction in costs that accompanies the grinding of the reduction roasted and quenched ore. The objective of this investigation was to study further this particular facet of the roasting-magnetic separation process.

Several previous research papers have discussed the effects of thermal treatment and cooling rate on the subsequent grindability of brittle materials. In general, it has been shown that heat treatment and rapid cooling can cause a marked improvement in ore friability. In addition, Person and Mitchell have studied a combination of heating, cooling, and reduction treatments on a nonmagnetic taconite. In their paper, the authors have shown the general effects that these variables have on the grindability of the ore in that heat treatment, rapid cooling, and roasting all improve the grindability of the ore; however, no attempt has been made to refine these effects.

By |2019-06-24T17:26:11-04:00June 23rd, 2019|Categories: Grinding|Tags: |Comments Off on Nonmagnetic Taconite Grindability – Influence of Reduction and Thermal Shock

In Situ Leaching of Uranium

Sedimentary deposits contain an appreciable portion of the world’s supply of uranium. Predictions of nuclear fuel usage in the United States indicate that these reserves will have to be tapped if the domestic industry is to be the major supplier of fuels for the nuclear reactors. Techniques developed within the petroleum industry are a base on which to build economically attractive fluid mining processes for the recovery of these uranium values. The problems central to the success of such mining processes are the containment, control, and recovery of a narrow band of pregnant leach solution as it progresses from the point of injection to the point of production.

Occurrence of Uranium

Uranium is not a particularly rare element in the earth’s rust. Kirk and Othmer state that uranium is more abundant than cadmium, bismuth, mercury, and silver. About one-third of the world’s uranium reserves are in sedimentary deposits. To date, most of the uranium mining has been in arkosic sediments.

Sedimentary sandstones, generally, contain little uranium. Two notable exceptions to this rule are the carnotite deposits of the Western United States and Kazakstan in the Soviet Union. The carnotite deposits of the Western United States are irregular and scattered, and yet

By |2019-06-24T17:24:14-04:00June 22nd, 2019|Categories: Leaching|Tags: |Comments Off on In Situ Leaching of Uranium

Improving Crushing & Grinding Rates and Recovery Efficiency

The crushing section was designed to supply approximately 100 tons per hour of -5/8 in. material to the Fine Ore Bin. Early milling results indicated that the ore was somewhat harder than expected and the 7 ft. x 10 ft. Hardinge Rod Mill was proving to be a bottleneck.

The comparatively wet ore, sizing up to 14 in., is fed from underground to a 36 in. x 42 in. Buchanan Jaw Crusher, crushing to approximately -6 in. size. This feed passes to a 16 ft. x 5 ft. Double-deck Horizontal Telsmith screen.

It was mentioned earlier that there had been a bottleneck in the rod mill with the underflow from the 1½ in. x 5/8 in. screens therefore all three 4 ft. lengths were changed to 1½ in. x ½ in. In addition it was suggested that the orientation of the slots be changed to “across-the-flow” as we were experiencing a lot of blinding possibly due to both the shape of the feed and the dampness of the ore.

These changes, however, lowered the crushing rate to approximately 70 tons per hour, increased the circulating load of rock both above and below the 2 in. size and gave excessive ammeter readings on the

By |2019-06-24T17:22:56-04:00June 22nd, 2019|Categories: Grinding|Tags: |Comments Off on Improving Crushing & Grinding Rates and Recovery Efficiency

Heap Leaching Oxide and Sulfide Copper Ores

Heap leaching is a simple means of recovering copper from oxide and oxide-sulfide ores. Although this method requires relatively low capital investment, it suffers from low copper recoveries and relatively high acid consumption. The objectives of this study were (1) to determine what factors influence these shortcomings, and (2) to establish a basis of correlation between laboratory and field testing.

The principal methods of leaching copper ores at the present time are heap, dump, in-place, and vat. A number of references are presented in the bibliography on the theoretical and practical aspects of these methods.

In the heap-leaching method, crushed or uncrushed oxidized copper ore is placed on a prepared drainage pad. Acid leach solutions are distributed over the top of the heap, caused to percolate downward through the ore bed by gravity, and are drained from its base. The leach duration is generally a matter of a few months.

Dump leaching is used to recover copper from very low-grade oxide-sulfide pit-waste materials. Here again, leach solutions are percolated downward through a heap. However, in this method, little or no acid is added to the leach liquors prepared drainage pads are not used and the leaching cycle is generally measured in terms of

By |2019-06-24T17:23:46-04:00June 22nd, 2019|Categories: Leaching|Tags: |Comments Off on Heap Leaching Oxide and Sulfide Copper Ores

Mathematical Modeling applied to Analysis and Control of Grinding Circuits Simulation of Closed-Circuit Grinding

The data acquisition and modeling efforts are described first, followed by discussion of some of the simulation results. Observations pertinent to steady-state operation are presented followed by a description of the application of a dynamic model of the grinding circuit for synthesis and evaluation of grinding-circuit control.

Data Acquisition and Reduction

Eleven streams are identified. Stream 1, shown as a dashed line, indicates the rod-mill discharge could be fed directly to the ball mill, or it could be directed via stream 6 to the ball-mill discharge, or it could be split sending slurry each way. This permitted the investigation of two different modes of operation plus combinations of the two, thus allowing an excellent test of the ability of the model to account for modifications in circuit configuration.

The set of data taken for this system contains a considerable amount of redundant information. For example, only two of the three particle-size distributions around the cyclone, streams 3, 8, and 9, are independently specificable. Consequently a balance around the cyclone can be used to independently determine the particle-size-distribution information. Likewise, the circulating load can be computed from particle-size-distribution data or from total mass balances.

The approach developed for analysis of the data

By |2019-06-24T17:21:15-04:00June 22nd, 2019|Categories: Grinding|Tags: |Comments Off on Mathematical Modeling applied to Analysis and Control of Grinding Circuits Simulation of Closed-Circuit Grinding

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