Mineral Processing Engineering

Manganese Removal Case Study

The Problem

Relatively low manganese levels in water can result in tainting of taste as well as discoloration of the water and the surfaces it comes into contact with. The Drinking Water Inspectorate (DWI) in the United Kingdom have set a maximum allowable limit of 50ppb, well below the WHO guidelines of 400ppb. While the WHO regulations are based on health concerns of the bioavailable form of manganese the DWI regulations are concerned with providing drinking water at the point of use which also looks healthy and tastes good i.e. free from discolouration and taint.

The 50ppb limit set by the DWI was intended to ensure that discolouration and taste tainting was acceptable to the consumer. However, recent studies conducted by Welsh Water and Severn Trent have shown that levels as low as 2ppb can still be problematic at the point of use.

Flushing pipework to remove the contamination on a regular basis is time consuming, disruptive to the consumer and expensive. In an attempt to develop a more viable treatment system that can produce water with a manganese concentration below 2ppb Welsh Water partnered with Amazon Filters Ltd to look at an

Nuclear Detector for Beryllium Minerals

Beryl is a mineral that may be difficult to distinguish from quartz by casual field inspection. The easily recognized green color and hexagonal crystal form of coarse-grained beryl are by no means universal, even in beryl from pegmatitic deposits. If it occurred as a fine-grained accessory mineral in an igneous rock, it would almost certainly escape detection unless samples were submitted for petrographic or chemical analysis. There may be substantial deposits of some beryllium mineral, other than beryl, that has been overlooked because that mineral also closely resembles the common rock-forming minerals.

The original discovery of the neutron by Chadwick in 1932 resulted from experiments with another nuclear reaction, induced by bombarding beryllium with alpha particles in which the products are carbon-12 and neutrons. The equation for this reaction is as follows:

Experimental Work: The experimental work was carried out by bombarding samples of beryl and of metallic beryllium with alpha particles from a polonium-plated silver foil.

The method of preparing the mineral sample was dictated by the need to get a large amount of the sample at a uniform distance from the polonium source. Therefore the mineral sample, usually a piece of beryl several

True Tensile Strength of Rock – Determination Method

Several methods have been proposed for determining the tensile strength of rock. These have been tried out over the past several years, but the results have been erratic and of doubtful value.

The tensile strength of rock is its weakest property, and this property apparently enters into all failure phenomena whether underground or on the slope of an open pit. Therefore, it is essential that detailed quantitative information is known about the tensile strength of rock if the design engineer is going to select the proper pit slope, pit orientation, or orientation of underground workings so as to give the most economical and safest mining condition.

The ratio of maximum to average stress at the plane of failure has been determined to be about 1.75. Professor Muerker’s method appears to give good results, but the major difficulty of this test is the preparation of the specimens.

Another method that has been suggested. This method is probably the simplest to use, but requires the use of cylindrical specimens. If a disc is compressed at opposite ends of a diameter by knife edges, it can be shown theoretically that there exists a tensile principal stress of constant magnitude across this diameter that tends to pull

Magnetic Reduction of Jaspilite in a Shaft Furnace

Jaspilite a mineral consisting of silica and iron oxide in varying proportions, is one of the host rocks of the high grade ore deposits situated in the Middleback Range of South Australia.

Selection of the Furnace

Basically, the magnetic reduction process requires that the jaspilite be maintained in contact with a reducing agent for sufficient time at a suitable temperature.

In practice, there are several methods available for achieving the necessary time – temperature relationship.

Of these, the tandem shaft furnace was chosen for the following reasons.

Both solids and gases leave the furnace at relatively low temperatures, so that heat economy is high.
The recirculation of exit gas allows close control of gas composition which will prevent the reduction proceeding to lower and nonmagnetic oxides.
Lump jaspilite may be treated and thus a minimum amount of comminution is necessary prior to reduction.

Description of the Pilot Plant

Jaspilite, supplied at minus 4 inches from the quarry, was fed to a 24″ x 12″ jaw crusher. After passing over a doubledeck, vibrating screen it was fed at the desired size to the furnace hoppers by an inclined belt conveyor. From the bins, the ore flowed by gravity through the furnace and was

Magnetic Recovery of Germanium Sulphide

The Kipushi deposit, where the Prince Leopold Mine has been installed belongs to Union Miniere du Haut-Katanga and is located in the Belgian Congo, 20 miles SW of Elisabethville, at the vicinity of the Northern Rodhesian Border.

How does germanium occur

Differentiation of renierite from regular bornite on a freshly cleaved surface is uneasy, but after a few hours of exposure to the air, the bornite turns pink, blue and finally violet, where as the renierite remains unaltered. In the long run renierite eventually shows a brass, brownish shade which cannot be mistaken for the color of bornite.

Renierite obeys a complex chemical formula, where positively charged ions are in excess. Composition of germanite differs from that of renierite by a lower ion and higher germanium content.

Magnetic properties of renierite

One of the properties that has long been known about the Kipushi “orange bornite” in the possibility of influencing a compass needle by bringing it near a relatively massive sample of this mineral. Grains of renierite, on the other hand, ground to a few tenths of a millimeter, react more or less to the presence of a permanent magnet some of them

Flocculation Testing to Improve Filtration

Two growing problems confront the preparation engineer—still further restrictions on stream pollution and a greater proportion of fine coal as more and more continuous miners come into use. The dewatering screens, centrifuges, and settling ponds that sufficed a few years ago must often be supplemented by more effective equipment, and in some instances the finest solids are now being recovered by vacuum filtration, once considered too costly in many coal washeries.

Slurries and Flocculants Tested: First of the slurries was the thickener feed from the washed coal section of the Michel colliery of Crow’s Nest Pass Co. Ltd., Michel, B.C.

Slurry was also obtained from the Black Diamond washery of Palmer Coking Coal Co., King County, Wash. This underflow of a ½-mm vibrating slurry screen is a waste product discharged to a settling pond. As shown by the data in Table I it contained about 20 pct material finer than 200 mesh, which analyzed 77.5 pct ash, indicating a high proportion of clay. The coarser sizes were also high in ash content because of the presence of bone and shale. Black Diamond coal is on the dividing line between bituminous and subbituminous rank.

Laboratory Experiments and their Relation to Plant Design

Laboratory experiment as a basis of commercial plant design has been the subject of much analysis and thought and on which a large number of articles and papers have been published. We would be forced to choose between an unduly brief exposition if we wanted to cover it completely, or no exposition at all.

How much of this fundamental scientific attention has, as a matter of fact, been accorded to the subject, mainly by our sister profession, Chemical Engineering. The close similarity to chemical engineering problems that we meet, praticularly in hydrometallurgical operations, suggests that Chemical Engineering publications offer a rich source of information and discussions of methods useful to us. We have only to think of pressure leaching, ion exchange, liquid-liquid extraction, precipitation and so on, all problems in chemical engineering unit processes or of the new Freeport Sulphur Nickel plant in Cuba or the Sherritt Gordon plant and many others.

In the design of any commercial plant, problems arise which cannot be answered by laboratory tests, but their neglect would seriously jeopardize the success of the venture. We only need to think of accessiblity for ease of operation, supervision and maintenance, materials handling, storage as well as others which are

Selecting Grinding Equipment

The selection of grinding equipment requires a consideration of the purpose in grinding, the characteristics of the material to be ground, equipment available for grinding, and the manner in which it can be applied best.

How is Equipment Selection Made

It is obvious that coal to be used as a pulverized fuel will be pulverized dry. It is just as obvious that cement clinker must be processed into cement by dry grinding,

Some materials must be ground without contact with metallic surfaces, which would contaminate the product. In these instances, grinding equipment is restricted to pebble mills and autogenous mills, and grinding may be wet (using water, oils, acid solutions) or dry. Also, where very fine products are wanted in a dry state, ceramic-lined, fluid-energy mills are used.

H – Hard, abrasive (silica, corundum, calcined coke)
MH – Medium hard (limestone, barite, apatite)
S – Soft, non-abrasive (talc, gypsum, bituminous coal)
T – Tough, fibrous (mica, asbestos, wood)

Product Characteristics:

G – Granular (closely sized)
F – Fine (< 150 microns, 100 mesh)
SF – Superfine (<30 microns, 400 mesh)

Experience and History

Thousands of grinding mills of all types, grinding many different materials, provide much of the knowledge

Granite Ore Fragmentation

The degree of fragmentation obtained in primary quarry blasting has always been a factor in the speed of digging the muckpile.

The quarry under discussion is fairly new, located in Georgia, and is in the large operation category. Loading is done by three yard shovels, and primary crushing by a 48″ x 60″ jaw crusher preceded by a 5″‘ wide feeder. The stone is a hard granite gneiss, of Los Angeles rating 22, and apparent specific gravity is 2.68.

It became obvious that considerable time was being lost in the removal and handling of large rock from the muck pile. Stopwatch studies showed that as much as one-third of the available shovel digging time was being lost to this cause.

In the course of one year, experiments were conducted on many types of powder. Prills were not tried, as water was present in most holes. It was found that thorough fragmentation became increasingly better as slower powders were tried. In the final analysis, a high ammonia-low nitroglycerine powder having a confined speed of only 9500 ft/sec has given the best results in this hard granite, this being considerably slower than the 20,000 ft/sec ammonia gelatin originally used.

The drilling pattern finally selected as optimum

Effect of Pulp Depth and Initial Pulp Density in Batch Thickening

The two principal attributes of a thickener pulp are its settling rate and the ultimate pulp density of the thickened mud. Testing for evaluation of thickening attributes of a pulp has usually been done batch-wise by placing the pulp in a one-liter glass graduated cylinder and noting the position of the boundary between clear liquor and mud as a function of time. Refinements in testing have included repulping a thickened mud to various dilutions and evaluating the settling rate on these various repulped muds. This is considered to make possible an estimate of the settling rate as a function of pulp density and therefore to pinpoint the slowest settling pulp which ought to be critical from the standpoint of thickener plant design.

The effects of pulp dilution on sedimentation behavior on pulps ranging from 2.44 to 16.7 pct solids initial pulp density, flocculated with Separan and charted in the traditional manner. At least two of the lines appear nearly straight in their early sections, but neither of the others does. Each of the curves in this figure includes a region labeled

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