Environment & Tailings

Water Industrial Mineral and Industrial Nuisance

Water occupies a dual role in our industrial society. It is the indispensable raw material, essential to life itself. It is equally an industrial nuisance, interfering with the production of industrial minerals, making construction difficult, flooding valuable land, and generally producing problems because it is in the wrong place at the critical time.

Gravel or Water

The valley of the Ohio River is underlain by deposits of gravel, sand, silt and clay. Generally, coarse, clean, sands and gravels underlie the silts and clays. The river itself is controlled by a series of navigation dams and the channel is dredged occasionally as the needs of navigation are recognized and met.

In many places, along the bank of the river, well fields have been constructed. The water derived from such well fields is usually water that originated in the Ohio River and passed through the underlying sands and gravels until it reached the well, in the process, the water has been filtered and naturally purified/ and is bacteriologically safe without further treatment. The result is a low-cost water supply of excellent quality and computable quantity.

The well fields so established do not operate at uniform offtake rates the year around. From time to time,

Tailing Pond Design

There are no hard and fast rules for Tailing Pond or damn Design, and each case has to be analyzed individually because of special conditions encountered at each location. Certain criteria are used for building dams at Climax, Colo., where they must be placed in rather steep mountain valleys on foundations that are practically impermeable.

The earthen toe dam which impounds the initial tailing is the key to the stability of the tailing dam; the toe was placed where proper foundation materials existed. Stability of the soils was investigated and evaluated under the earthen toe dam and along the toe of the tailing above the earthen dam. The peat bogs which ranged up to 8 ft deep were removed and the soils were investigated to insure that these materials would develop ample friction and be stable and relatively incompressible when subjected to superimposed weight. The bottom of the valley consisted of heterogeneous alluvial and slope wash deposits, and the area under the earthen toe dam was excavated deep enough to get below the seams of fine sands and silts that were encountered near the surface.

tailing pond design decanting tower


The tailing material at Climax

Wet Scrubbing of Coal Dust from Thermal Dryers

Wet scrubbing of fine coal from Thermal dryers poses a number of problems in adapting the gas cleaning equipment for required clean-up of the fine particulate matter.

A wet cleaning apparatus traps the matter suspended in the gas stream in a scrubbing liquid, generally water and a great variety of equipment is used. They include wet spray towers, packed tower centrifugal devices, Venturi scrubbers and various types of sieve trays.

The Peabody gas scrubber uses basic principles to effect gas cleaning; sub-division of the gas into small streams, impingement of the small gas streams against wetted targets at comparatively high speeds and centrifugal action to separate the particle from the gas stream. Figure shows a typical Peabody impingement baffle plate cleaning stage. This type of contact is used either singly or in combination with additional gas cleaning stages depending on the degree of difficulty of gas cleaning.

A typical performance curve showing cleaning efficiency of a single Peabcdy type tray is shown in Figure 3. A curve of this type is characteristic of all wet scrubbers. There is considerable variation in the performance of various types of wet collectors particularly in the range of 0 to 5 microns in size. It should be

Dispose Radioactive Waste by Hydrofrac Techniques

tilizing the technology developed for oil well stimulation by hydrofracing, a disposal system which permanently fixes the waste has been proven. Large quantities of radioactive waste can be processed by a single well system making this method an attractive method for permanent radioactive waste disposal. The system depends on locating a relatively thick formation of impermeable, but easily fracturable rock such as a shale, creating a horizontal fracture, pumping the waste into the fracture in a form which will subsequently solidify and seal the fracture from the well system.

Waste Disposal Technology

It would be impossible to completely present the literature of radioactive waste disposal research in the space alloted to this discussion because of the volume and diversity of field. A brief historical development supported by pertinent articles, is presented. Our active interest in the radioactive waste disposal problem began in 1956 with the expansion of our corporate research program to include possible applications of atomic energy to the petroleum business.

Members of our research group had been previously concerned not only with the disposal problems associated with the refining and production of oil, but also problems of stimulation of oil production using waterflood and hydrofrac techniques. It was a

Tailing Disposal

In order to avail the operation of maximum storage for the future, a uniform minimum grade launder was proposed with a minimum velocity and maximum outfall at the discharge. Disposal of the gravity and flotation tailing was formerly accomplished in open ditch from the concentrator at a grade of 1.5 percent. It was desirable to design the new launder at grades less than this for the greater storage elevation.

Prior to the installation of a final launder of 2,200 ft. in length, an adjustable test launder was constructed of 250 ft. in length in the existing tailing ditch to determine minimum grade for satisfactory flow of tailings.

Following extensive testing of launder grades, the main launder was constructed at one percent and placed in operation in December of 1962. Launder construction consisted of a 15 in. diameter semi-circular section of 12 gauge metal with 15 in. free board. Individual steel sections were 6 feet in length, supported on the upper edges by 4 x 4 wood stringers and framing. Metal sections were not continuously welded but tacked for installation with clamping angles on both top corners. Lining consisted of continuous 100 ft. sections of 84 in. wide 40 durometer natural rubber with

Tailings Disposal and Liquefaction

One of the many responsibilities of mining engineers and mill superintendents is to provide for the safe and economic disposal of wastes (or tailings) remaining after a mineral has been extracted from an ore. The cost of disposal of these tailings exerts a considerable influence on the minimum grade of ore extracted from the mine. It varies to a great extent with each project and is dependent on many diverse factors, such as the local topographical, meteorolgical, geological and seismological conditions together with the applicable water pollution laws of the area.

The liquefaction susceptibility of tailings deposits from a mining or chemical processing operation appears to be increasing, probably because the deposits are being built to greater heights and because the waste materials have a much finer gradation than before. Although there are many indications that mining engineers and mill superintendents are well aware of tailings disposal problems, it is apparent that many of those responsible for the layout and operation of disposal facilities are having difficulty getting rid of an immunity complex. However, this kind of thinking may well lead to disaster. Liquefaction failure is a very real danger in any deposit which has not been carefully planned and properly

Mine Drainage Control and Treatment

Standards vary from state to state for reasons which I find impossible to explain. For example, Pennsylvania has set an iron limit of 7 mg/liter (7 ppm) on the discharge from a treatment plant. West Virginia, on the other hand, has adopted 10 mg/liter (10 ppm) in the receiving stream as a satisfactory iron level, thus giving proper credit for the dilution effect of the stream. As you all know, public hearings are currently being held in all fifty states, attempting to develop stream standards which will be satisfactory to both the states and the Federal Water Pollution Control Administration. So, we still are aiming at a moving target.

Now, let’s consider the fate of the ferrous iron and the acid in the water as it moves—miles, in many cases—from its point of formation to its point of discharge. As all of you know, substantial amounts of limestone or calcium carbonate are associated with coal deposits.

The first reaction (Equation 1)—which occurs rapidly—is the reaction of the acid with, say, limestone. Bicarbonate ion is formed and acid in the mine water is neutralized.

After, or simultaneously with neutralization of the acid, another important reaction begins. You will remember that I stated that ferrous,

Design Lime Neutralization Mine Drainage Treatment Plant

The acid mine drainage problem in Pennsylvania is of continuing and growing interest to the coal mining industry, the state government and the citizenry at large. Approximately one-third of the total volume of mine drainage presently polluting the streams of the Commonwealth originates from active coal operations and two-thirds come from “abandoned mine discharges.”

The acidic contamination of surface drainage and mine drainage water from coal mines is normally caused by the oxidation of iron pyrites. Acidic drainage waters contain dissolved iron salts and varying proportions of other dissolved metals. These waters are slightly cloudy, although suspended iron oxides, coal dust, etc., may also be present.

Technically, any acidic effluent from any coal mine could be purified by chemical processes to any desired standard of purity. Chemical treatment has been applied successfully to similar effluents in other industries in order to make them suitable for discharge to municipal sewers or to natural water courses and investigations have confirmed that these processes could be applied to the acidic effluents under review.

The demonstration plant was designed so that it could be readily moved over existing highways and roads in the Commonwealth without special permits. The pilot plant was constructed in a van type trailer

How to Avoid Tailings Dam Trouble

Dams are constructed to retard the flow of water or debris; therefore natural forces are constantly at work to remove such obstructions. To circumvent nature and avoid expensive trouble with a dam requires thoughtful far-sighted planning, careful construction control and vigilant periodic inspections to detect and repair deterioration at its inception.

Although the factuality of the foregoing statements is apparent, all too many have failed to consider them in the past as will many in the future. “The economic, but safe construction of dams calls for the highest order of technical knowledge, practical experience and sound judgment.”

Special Geologic Considerations

A dam may be defined as an impervious membrane which is provided with some means of support and appurtenant facilities to permit the discharge of excessive quantities of flood water, as well as a means of utilizing the water from the reservoir, preferably without pumping. How this impervious membrane and its spillway and outlet works are constructed depends, or should depend, primarily on the local natural conditions, such as rainfall, foundations, abutments, available construction materials and the topographic conditions as they influence the location of the spillway and outlet works and stream diversion schemes. Arroyos have the unfortunate habit of flowing

Acid Mine Drainage Research

The problem of pollution of water by mine drainage is at least as old as the mining industry itself. However, research on the formation, composition, treatment, and abatement of mine water is a relatively recent historical event.

At Bituminous Coal Research, Inc., acid mine drainage control has been an important area of work since 1944, at which time BCR began sponsorship of research at West Virginia University. The work at West Virginia University involved a detailed study of the acid mine drainage problem and led to the identification of iron oxidizing bacteria as important factors in the formation of acid mine water.

Chemical and Physical Properties of Mine Water

In order to appreciate the intent of this work area, a brief review of the formation of mine water is necessary.

Acid mine drainage results from the dissolution of oxidation products of pyrite in normally alkaline ground water together with the subsequent dissolution of other minerals in the resulting acidic solution.

The mechanism of the chemical reactions involved in pyrite oxidation is complex. It has generally been represented by the following overall chemical reaction.

(a) FeS2 + 7O + H2O = FeSO4 + H2SO4

(b) 2 FeSO4 + O + H2SO4 ↔ Fe2(SO4)3 +

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