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Manganiferous Iron Ore Chlorination

The chlorination behaviors of pure iron and manganese oxides were investigated by combining a thermogravimetric analysis (TGA) technique with batch-boat roasting followed by leaching. Ferrous and manganous oxides could be chlorinated readily, but, in the absence of a reductant, the higher oxides of both iron and manganese were difficult to chlorinate. Thermogravimetric analysis curves were drawn to illustrate the complexities of the reactions, and the possible mechanisms were discussed. Then three manganiferous materials from the Cuyuna Range of Minnesota were treated by a process involving the selective chlorination of manganese followed by leaching. The results were interpreted in the light of the chlorination mechanisms observed on the pure iron and manganese oxides.

Materials

The pure ferric oxide used in the study was of analytical grade. Magnetite and wustite were prepared from the pure ferric oxide by heating it for one hour at 900°C in a mixture of CO and CO2. For the magnetite a CO-CO2 ratio of 1:10 was used, and for the wustite 1:1 was used. Pure manganous oxide was prepared by decomposing manganous carbonate of analytical reagent grade in a nitrogen atmosphere at 500°C. Manganese dioxide of analytical reagent grade was used as purchased. Manganese tetroxide was prepared

Slurry Pumps for the Long Pipelines

Since time immemorial, Mother Nature has been transporting slurries with both air and water serving as the carrier medium. Consider for example the formation of the continental shelves off our coast lines which are being formed by rivers emptying erroded land surface and depositing it into bays and gulfs. As the erosion processes take place, the fines are suspended in water which flows in streams and rivers and deposits where the velocity of the flow reduces sufficiently to allow the fines to settle out. The same process in some crude form is provided when one hoses his driveway or patio and moves dirt so as to provide a cleaning action.

The movement of liquids in pipelines necessarily occasions the use of pumps for the purpose. Those of us who have had some rub with the petroleum industry are familiar with the transport of solids through mud pumps and cementing and fracturing pumps where the movement of slurries is an everyday matter. In the drilling of an oil well the circulating fluid utilized to remove chips which are cut by a drill bit from holes drilled deep in the earth is called drilling mud. This substance contrary to what the name might

Separation Efficiency

The technical excellence of separation achieved in a mineral concentration process, or any other process where two constituents of any kind are physically separated from each other, is expressed uniquely and quantitatively by the Separation Efficiency:

Es = (R – Rg)

where R is the percentage of the valuable constituent and Rg the percentage of the waste appearing in the concentrate. The Separation Efficiency meets all the usual requirements of a true efficiency and is independent of the nature of the process used. It can be visualized as the percentage of the feed material that, in effect, actually undergoes complete separation while the rest of the feed is distributed randomly and unchanged into the two separation products.

Mineral Concentration Processes and their Evaluation

The overall concentration process may be subdivided into one of liberation, which severs the bonds between unlike mineral species, and another of separation, which sorts the resulting liberated particles into two products, a concentrate, rich in mineral “A”, and a tailing, lean in mineral “A”.

A perfect mineral concentration process is represented by the idealized scheme shown in Figure 1 in which liberation and separation are not differentiated. The feed mixture consists of two types of minerals which

How to Select Grinding Mill Liner Alloys for Optimum Wear Resistance

The wear resistance of an alloy in heavy mill liner sections may be quite different from that of the same alloy in small balls and other light sections. This fact was established by means of a well standardized laboratory test that was validated for ball mill service. The salient properties of mill liner alloys, including austenitic manganese steels, medium alloy hardenable steels, and abrasion resistance cast irons are described, critically compared, and quantitatively ranked in terms of mill liner service.

Where they are tough enough the high-chromium and other martensitic cast irons (e.g. Ni-Hard) promise maximum economy, but their section sensitivity is a limitation. To overcome this an extensive research program studied over a hundred experimental alloys, ranking them for heavy section abrasion resistance by means of the laboratory test.

Criteria for Abrasion Resistance

There is a widespread tendency to accept hardness as an index of abrasion resistance. Most hardness tests provide a measure of compressive strength, e.g. the common Brinell test is reported in terms of a Brinell Hardness Number (BHN) that is the compressive strength of the metal tested in kilograms per square millimeter. The numbers can be converted to pounds per square inch if desired. Such values are

Removal of SO2 and Production of Sulfur from Smelter Gases

The economic removal of SO2 and production of elemental sulfur from stack gases discharged by base-metal smelters is a challenging-goal. Annually, in the United States, about 3.5 million tons of SO2 are discharged to the atmosphere by smelters. The SO2 concentration of the gases ranges from about 0.5 to more than 3 percent. As the sulfur content of SO2 is 50 percent, a potential production of 1,750,000 tons of sulfur per year is indicated.

The base-metal smelting industry in the United States now recovers part of the SO2, converting it to H2SO4. An outstanding example is the Kennecott smelter near Salt Lake City, where up to 80 percent of the SO2 is recovered as H2SO4. At many smelters, however, no SO2 or only a minor amount is recovered and converted to acid, primarily because of a lack of markets or because the gases are too dilute to permit economic production of sulfuric acid.

The removal of SO2 from a stack gas is not difficult. Scrubbing the gases with alkaline solutions, such as sodium carbonate, ammonia, or a slurry of lime, converts the SO2 to a mixture of sulfites and sulfates; but these solutions cannot easily be regenerated to recover sulfur or sulfuric

Reduction and Approximate Solutions of the Batch Grinding Equation

A principal first order and a minor summation term contribute to the solution of the discretized batch grinding equation when formulated in cumulative retained mode. Depending on the interrelationships between the selection and breakage parameters, the minor term may be advantageously modified in a number of ways.

grinding-equation

where Mi(t) is the mass fraction of particles identified by i-th- size index at time t; Si, the selection function, is the rate of breakage of particles of i-th size, and the breakage function, Bj i, is the i-th size fraction of products when particles of size index j are broken. The practical solution of Equation(1) becomes progressively tedious for i>2. Thus, for i = 3, the solution is

The cumulative fraction of particles retained on i-th size is

grinding-equation-3

grinding-equation-4

grinding-equation-5

Mj(t) = Rj(t) – Rj-i(t)……………………………………………………..(6)

grinding-equation-6

Although not strictly necessary for the approximations to be made later on, it is convenient to assume that cumulative breakage function is normalizable which for particles distributed on a mesh scale

Recover Copper from Reverberatory Furnace Slag

Laboratory and pilot plant investigations have indicated that copper recoveries of 50% can be achieved with fine grinding and flotation of a copper reverberatory furnace slag. Microscopic and microprobe studies indicate that the recoverable copper is in the form of matte, chalcocite, and metallic copper; the percentage of copper in particles appearing to be copper-free was from 0.23 – 0.54%.

eratory slag from the White Pine slag dump and most probably represents a wide variation in slag composition.

A significant amount of matte and some metallic copper was observed in the preliminary evaluation. Inasmuch as these particles appeared in the +48 mesh range, gravity concentration was considered. The feed material was stage ground to 35 mesh and treated by tabling. This operation produced a concentrate which assayed 10.6% Cu and contained 13.0% of the copper present in the feed material. Subsequent microscopic observations indicated that the majority of the recoverable copper values occur as finely disseminated particles, and fine grinding followed by flotation appeared to be the most reasonable approach for significant copper recovery.

esults on the fourth day, using 0.06/ton of collector (sodium isobutyl xanthate) and a grind of 87% minus 400 mesh, show a good grade (16.9% Cu) but less than 50%

Slurry Pipeline Cost Estimation

The transportation of mine products incurs a cost which can have a significant bearing on the competitive position of the manufactured product. Clearly, the engineer who is responsible for selecting a mode of transport must base his decision, at least in large measure, on economic comparisons. And today, the engineer usually finds that he has to choose between several modes, including slurry pipelines. Several design variables affect the total transportation cost. The amount of preparation that is required to make the solid material into a satisfactory slurry is an important factor.

slurry pipelines summary

Pumping velocity is another critical variable in slurry pipelining. Next figure  illustrates the general relationship between pressure drop and rate of flow; it also illustrates the concept of critical velocity. The straight portion of the curve, between Points “A” and “C”, encompasses the velocity range at which the solid material is suspended in the carrying liquid. However, as the velocity is decreased from Point “A”, the uniformity of suspension gradually decreases. This decrease continues until, at Point “C”, part of the solids are being conveyed along the bottom of the pipe. At Point “D”, a bed of solids has formed.

Self-Fluxing Pellet Production

The development of pelletizing during the last ten years has continued, however, self-fluxing pellets have not been regularly and commercially produced for use in blast furnaces, except as Kobe Steel, Ltd., Japan. This paper tells about unique developments for self-fluxing pellets, and their effects when used in Kobe Steel’s No. 3 blast furnace at the Nadahama Works (inner volume 1845 Nm³, hearth diameter 9.5 m). Several phases of the pelletizing process are discussed individually, and also their relation to performance in blast furnace operation. Special emphasis is placed on proper preparation of the limestone added to the raw materials, and indurating at optimum conditions. Means of improving pellet quality by correct control of size distribution of the raw materials used in pelletizing, and indurating temperatures, are also discussed. As basicity (CaO/SiO2) of pellets increased 0.1, coke consumption decreased 3. 8 to 4. 2 kg per ton of hot metal, when using 70% pellets in the iron burden.

Fundamental test on production method

The self-fluxing pellet is made from a mixture of fine ore and ground limestone. Although it is assumed that the size and indurated condition as well as mixture rate of limestone have effects on green pellets and indurated pellets, no

Predicting the Block Caving Behavior of Orebodies

Block caving is an efficient mass-production method for the underground mining of large orebodies. However, the block-caving method requires a substantial investment in developmental works, based on the assumption that the rock will cave.

Efficient block caving is prevented if the rock forms stable arches or breaks into fragments that are too large to pass easily through the finger raises. Under these conditions, the cost of the additional labor, drilling, and blasting required to assist caving may be sufficient to make marginal orebodies uneconomic or alternative mining methods more attractive.

The purely geological aspects of block caving were studied by means of geological indices. These are easily measured and reproducible, numerical properties of the rock mass. Relationships between the various indices and such rock mechanics parameters as compressive or tensile strength and deformation moduli can be established by correlation with test results. The aim of this part of the study was to determine which of the many possible geological indices was most highly correlated with some independent measure of block caving behavior. Clearly, the first step was to set up a measurement of block-caving behavior or “cavability.”

At the beginning of the study, there was considerable feeling that a composite index of cavability

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