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Effect of Partial Removal of Xanthate Collector on Size of Material Floated

Sulfide copper, zinc and iron concentrates are recovered in the 5000 ton per day flotation plant operated by Cities Service Company at Copperhill, Tennessee. The heavy-sulphide ore is first ground to 50 pct. minus 200 mesh and a bulk concentrate floated. The bulk concentrate, over 60 pct. of the ore weight, is reground to 72 pct. minus 200 mesh and then treated in a selective flotation circuit to recover copper and zinc concentrates. The tailing of selective float is the iron sulphide material source for the manufacture of sulfuric acid and iron sinter.

The collector addition in the bulk rougher float is a sodium ethyl xanthate solution. The pH at the head of the circuit is 5.5 but neutralization by calcite in the ore raises the pH to 7.0 at the tailing end. Sulfuric acid is the regulator.

The xanthate concentration in the tailing solution was found to be between 1 and 2 ppm. This was about as expected. The 59.6 ppm. residual xanthate in the concentrate pulp after the lime slurry addition confirmed an interpretation of the finding of Bushell and Malnarich. The tests indicated the xanthate put into solution by a rise in pH would go back on to a

Ultrasonic Level Sensors

Ultrasonics, by simple definition, are sound waves beyond the audible range of the human ear and are generally accepted to be waves over 20,000 cycles per second. When applied to level measurement, the principles of ultrasonics are basically quite simple. A sound pulse is initiated at a point in time and the time interval for the echo from that pulse to return can be interpolated into distance.

A brief explanation of the hardware involved in an ultrasonic application may prove helpful. A sensor, which consists of a crystal housed and encapsulated with an epoxy compound is mounted in a sensor enclosure made to various specific sizes and shapes and manufactured from varied materials to handle the ranges and environmental conditions as required for the application. The sensor is connected by means of a standard coaxial cable to an electronic unit. The electronic unit, which might be called the heart of the system.

The industrial applications to measure the level of iron ore, coal, minerals and chemicals of all types and liquids including very strong acid and caustic solutions. Level controls on tripper control systems and multiple bin applications are becoming very widely accepted. Each application is different and can be made to

Tumbling Mills Power

Based on a simplified model for the motion of particulate materials in horizontal, rotating cylinders, approximate expressions have been derived relating the power consumption of a tumbling mill to its dimensions and speed of rotation and to the amount and nature of the charge. The basic assumptions underlying the model are that there is no slip between the charge and the mill shell, that the free surface of the charge remains essentially planar during rotation and that there is no transfer of momentum from the material flowing down the free surface back to the mill shell.

The Behavior of Particulate Materials in Rotating Cylinders

In the context of this approach, it can readily be shown (see for example Rose and Sullivan, that the form of the equilibrium surface is given by

R = Ce eψ tan α

where R and ψ are the polar coordinates of a general point on the surface, α is the angle of repose and Ce is a constant, depending on the filling, speed of rotation, and angle of repose. The origin of the coordinate system is located on the vertical axis passing through the center of the mill at a distance g/ω² above the center.

Treatment Methods for Mining and Ore Processing Wastewaters

Increased emphasis on industrial pollution control has intensified investigation of waste treatment technology for methods of reducing the amount of pollutants discharged by industry. The mining and mineral processing industry can point to a record of considerable accomplishment in the field of wastewater treatment and reclamation because these operations are so frequently an integral part of the entire operation of an ore dressing facility.

Neutralization of excessive acidity or alkalinity in wastewater is a fundamental pollution control measure that is required to preserve receiving stream biota. A wide variety of materials are available for pH adjustment but for large consumptive uses first consideration usually is given to a low-cost material such as lime or limestone for acid neutralization and sulfuric acid or carbon dioxide for alkali neutralization. Since neutralization may involve many factors in addition to pH adjustment, the chemical characteristics of the wastewater must be considered.

The use of limestone for neutralizing acidic wastewater is often attractive because this material is available in many areas at the lowest cost per unit of basicity. However, limestone neutralization has a reputation of limited reliability due to the high incidence of failures recorded in the past. It is important, first of all, to establish

Thickener Design and Theory Problems

This paper will review thickening theory, from the study but of the practicing engineer, with particular emphasis on areas of uncertainty or disagreement. It will attempt to outline broadly what we know and what we don’t know. This should serve two purposes. First, it will warn the process engineer where he might get into trouble. At least it will alert him to the risk involved in uncritically accepting any of the recommended design procedures. Second, it will identify for researchers some areas in which further work might be fruitful.

“Thickening” means different things to different people. For this paper we define it to mean sedimentation behavior characterized by line settling. Solids subside with a clear line of demarcation between settling solids and supernatant. Although the supernatant will usually be clear, in some cases it may be turbid.

Thickening Regimes

Coe and Clevenger believed that throughout “free settling” the settling velocity u was a function of C only. In mathematical terms, u = u(C). About compression they made the following statement:

“The water liberated by compression finds its way out of zone D” (their compression zone) “through tubes or channels which form drainage systems upwards through the zone.”

Thus they conceived channeling to

Tailings Dam Sealed by Slimes Slurry

In 1965, Monsanto started planning of a new dike (No. 15) for use in disposing of ore tailings at its Columbia, Tennessee phosphorus plant. Generally, in the phosphorus industry only clay tailings are produced making it necessary to borrow fill for construction of a retaining dike. Borrow area investigations indicated that weathered shales and limestones adjacent to the dam site would provide adequate construction materials. It was proposed that the more clayey weathered shales would be used for the impervious core and the more granular weathered limestones would be placed in the outer shell of the dike.

Reduction of seepage through an embankment by approximately 30% was successfully accomplished by a technique of allowing tailings fines to be transported into the embankment materials. The bulk of these fines were in the 0.5 – 0.01 micron size range. The advantage of the method is its self-healing quality, i.e., as the tailings level of the impoundment rises the clay fines percolate into pervious areas of the embankment, thus sealing it. The technique used by this work, however, was to accelerate the healing process by artificial placement of fines on the embankment face at pond levels well above the tailings layer.

Seepage on the downstream

Electrochemistry of Pyrite and its Significance in Sulphide Flotation

In spite of the importance of the presence of pyrite in the flotation of sulphide ores, not many studies have been made from the electrochemical point of view. It is generally recognized that the oxidation of sulphide minerals is one of the most important factors among those which affect the floatability of sulphide minerals. The concept that the presence of oxygen is essential to the flotation of sulphide minerals is supported by numerous experimental results.

Electrochemistry of Pyrite

The rest potential of pyrite, corresponding to the open circuit (no net anodic or cathodic current) in 1NHClO4 was observed to be +0.62 volt vs. the standard hydrogen electrode (SHE). This value is consistent with those reported in literature’s, but is not expected, considering the equilibrium between pyrite and per chlorate solutions at pH=0. The equilibrium potential expected from the potential -pH diagram is at 0.35 volt at 1M Fe++ and would go to lower values in solutions more dilute in iron. The rest potential observed for pyrite is, in fact more noble than that observed for any other sulphide mineral or synthetically prepared sulphide matte.

The stoichlometry of the anodic reaction is of interest at potentials below 1.0 volt, where oxygen discharge

Stability of Lead Ethylxanthate in Aqueous Systems

In galena flotation, lead ethyl xanthate, Pb(EtX)2, is precipitated and is physically adsorbed in the form of multilayers on the chemically adsorbed first layer of Pb(EtX). The solid particles are coated with layers of Pb(EtX)2 in heterogeneous manner over surface areas possessing both anodic and cathodic character. It is anticipated that the mode of formation of Pb(EtX)2 and the number of ions present, together with stable or unstable by-product species, have great influence on the surface characteristics of galena. The information obtained from a study of these parameters may have important practical applications in flotation

The precipitation study of Pb(EtX)2 was done utilizing the quick experimental techniques reported by Tezak and his associates and by Matijevic and his collaborators. A series of aqueous solutions of Pb(NO3)2 and of KEtX at 6.5 pH values and of various known concentratlons were prepared. The reacting solutions were mixed rapidly by putting 5.0 ml of one solution into the same volume of the other reactant in well-cleaned test tubes. Each test tube was shaken for one minute and was left in a constant temperature bath at 25°C.

The study concerning dissolution and decomposition of Pb(EtX)2 was carried out in a double-wall thermostatic reaction vessel. For each

Sphalerite Activation by Copper Sulphate-Cyanide Combination

The main constituent of the feed to the “Sulphide Section” (31 t/h), in the F. Sartori Plant (6000 t/d) of the Miniere di Monteponi(Sardinia), is the ore of the Campo Pisano – Funtanaperda Mine. Difficulties have always been experienced in the treatment of this ore, owing to the extremely fine Pyrite-Sphalerite intergrowth and to the high Pyrite and soluble salts contents.

Preliminary Considerations

In connection with what has been reported above, the depressant, needed for pyrite, should:

  1. Work at neutral pH
  2. Not be consumed by the soluble salts
  3. Be most effective in the same conditions, in which the soluble salts are less deleterious or in which some of them may even enhance the action of the depressant.

It is known that ferrous and ferric ions, in presence of copper sulphate, and of xanthate as a collector, tend to lower the floatability of pyrite with respect to that of the other sulphides.

When working with pure solutions containing CuSO4 and at least 0.03 g/l of Fe as ferrous sulphate, one may succeed in preventing the pyrite-air bubble contact at pH 6.2 to 9.0, if the surface is slightly oxidized, and at pH 4.5-6.2, if the surface is fresh (see fig. 2 at NaCN

Solving Industrial Mineral Flotation Problems

Flotation was practiced by this and succeeding engineers to concentrate many of the non-metallic minerals available from Canadian resources. Experimentation, and some extensive experimentation. A number are still under investigation. A few have evolved into producing plants. The results obtained for some have been used to increase efficiencies in existing plants. Results for others have been applied in comprehensive pilot plant operations.

flotation projects

 

The Flotability Program

The overall intent of this program is to assist in the solution of non-metallic flotation problems by pointing out possible areas for effecting separations. Considering the number of non-metallic minerals and the number of potential collectors it is a program which could be extended indefinitely. There is also a factor of change. Several reagents employed at the beginning of the program in 1959 are no longer produced. The provision of surfactants which can be broken down by natural forces, i.e. “biodegradable” after their primary function is fulfilled is becoming unescapable to manufacturers.

Results are reported as excellent, good, fair, or poor flotation and arranged according to class and type of collector. Known flotation systems for various minerals are usually confirmed and new areas for possible flotation are

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