Amalgamation

How Mercury & Gold Amalgamation Works

In order to keep the plates in proper condition so that successful amalgamation may be maintained, they must be prepared carefully, and the closest watch kept over them. The setting of the plates has already been described on p. 121. The silver-plated copper table is preferred in California from the ease with which it is kept clean, but is not used in the Transvaal. It is not considered desirable to put on it as much mercury as it will hold, since, if the amalgam is too fluid, losses are sustained by scouring, but, on the other hand, if the amalgam becomes too hard and dry from absorption of gold and silver, further amalgamation is checked and fresh mercury must be added.

The condition of the inside plates is regulated by the amount of mercury supplied to the mortar. In Colorado there is an opening at the front of the battery and above the screen frame, ordinarily covered by canvas, which can be lifted up by the millman, who introduces his arm, and determines by passing his hand over the front plate, whether the right amount of mercury is being added by the feeder. The regulation of the addition of mercury is ….Read more

Gold Amalgamation Equipment

AMALGAM PRESS

The Amalgam Press is used wherever the process of amalgamation is practiced. The amalgam is wrapped in a wet chamois skin and inserted in the press, which extrudes the surplus amalgam. The press consists of a steel cylinder, slotted on the sides and perforated on the bottom. The steel piston is forced into the cylinder by a long machine screw driven by a convenient handwheel. Cylinder will hold approximately ten pounds of amalgam on each operation. Larger sizes furnished on demand. Shipping weight of press referred to is about 60 lbs.

Amalgam Press

AMALGAM SEPARATOR

SEPARATION of mercury and amalgam from ground sulphides, after barrel amalgamation, is quickly and efficiently accomplished by the use of the Mercury Separator. Other material having different settling rates can also be split by this unit.

A carefully controlled upward flowing stream of water in a pyrex glass tube effects the separation. Velocity of the water can be visually controlled and regulated by the operator so that the lighter particles overflow the top and the heavier settle in a glass jar. As a protection, tube is set in steel frame. Recovery of mercury is practically complete. Separation time is a few minutes against ….Read more

Gold Amalgamation

The purpose of the following research, as originally planned, was to investigate the influence of temperature upon the plate- amalgamation process. In order to consider the gold amalgamation process intelligently, it was first necessary to learn the nature of an amalgam. In the performance of this task it was found necessary to consult a large volume of literature and to perform experimental investigations. The conceptions of the nature of amalgams thus obtained have so important a bearing on the amalgamation-process as a whole, as well as upon the possible influences of temperature, that it was advisable to include them in the treatment of the subject. The broader title is therefore used, even though some features of the amalgamation process have been treated very briefly and others entirely omitted, there being nothing new to present regarding them and their development not required for a clear presentation of the matter in hand.

Gold Amalgamation Process History

Gold was one of the earliest metals known to man. Occur­ring in the metallic state, it could be picked up in nuggets or washed, as gold dust, from the sand and gravel of streams. In­teresting descriptions of the processes employed in early times ….Read more

Recovery of Mercury from Amalgamation Tailing

In this paper on the recovery of mercury as sulphide, from the residues from the amalgamation and cyanide treatment of high-grade ores and concentrates, I will not discuss the many reactions, chemical and otherwise, that take place in the general process, but confine myself more par­ticularly to the methods of recovering the mercury.

Recovery of Mercury from Amalgamation Tailing

I submit charts of two amalgamation-barrel charges, Figs. 1 and 2, which are self-explanatory. The flow sheet of the high-grade and the mercury extraction plants is shown in Fig. 3.

In the amalgamation of high-grade silver ores and concentrates in strong cyanide solution, as practiced in the Cobalt district, considerable mercury is retained in the residues from the amalgamation process. The greater part of this mercury is in the form of mercuric sulphide, from 5 to 10 per cent, only of the total mercury content being in the metallic state.

Attempts to eliminate this loss in the amalgamation process were made, but all resulted in a low extraction of the silver in the ore, and attention was then directed to the recovery of the mercury from the residues.

The process developed ….Read more

Amalgamation Of Gold Ores & Chloritizing Roasting

The following minerals could be plainly seen in the ore: magne­tite, pyrites of iron, pyrites of copper, quartz, and garnet. Neither galena nor zinc-blende were visible, but the ore contained a trace of lead, and in some samples of ore from the Muertos mine, 1.19 per cent, of zinc was found. Antimony and arsenic were not present. Native gold could scarcely be seen in specimens of the ore, and it only appeared—mainly in extremely fine particles—after pulver­izing and washing. Magnetite was in every instance the most prominent mineral, its quantity varying between 43 and 67 per cent. Determinations of copper and sulphur showed that from 3.5 to 7 per cent, pyrites of copper, and from 3 to 22 per cent, pyrites of iron were present.

The gold-value of the ore varied between 0.3 oz. and 0.8 oz. per ton. I do not speak of specimens, but of average samples of large quantities of ore put through the battery. In ore that had been crushed through a No. 40 screen, the gold appeared, in part, as free gold, the rest being thoroughly mixed with the magnetite and py­rites, both minerals containing about the same percentage of gold. If this free gold was ….Read more

Pan Amalgamation

These results obtained in experiments, proving that a low percentage of copper sulphate with a variable percentage of salt, depending on the ore, gives the best results, confirm practical mill-work. I have none of my notes, taken at the time, to refer to, so have to rely solely on memory, which precludes the conciseness that is always desirable.

At that time, the plant was treating a very refractory ore carrying about 15 grams in gold and from 20 to 25 oz. of silver per ton, the bullion being about 300 fine in gold. The silver in the ore was in the form of a sulphide.

Although carrying an average of 0.75 oz. of gold per ton, free gold could rarely be seen by panning, but upon roast­ing a sample of the ore the gold became visible at once—a result which was discovered by chance and used to advantage later.

In order to utilize the old mill to the best advantage, it was decided to use pan amalgamation after roasting. The roast­ing, done in a lime-kiln, was similar to the ordinary “burning” operation. The roasted ore was trammed to the mill-bins and crushed by 10 stamps to pass a 30-mesh screen. The pulp was ….Read more

Amalgamation Patio Process

The ores were composed principally of iron pyrites (much decomposed), in a quartz matrix, with native gold in very irregular grains. Some portions, however, carried their metallic value in a matrix of calcite and siderite. The mill in which the ores were treated consisted of two 800-lb. stamps, two amalgamating-plates, four pans, two automatic washers, two Frue vanners, and the necessary accessories for assaying, retorting and refining gold. The plant, originally erected with American capital, and directed by competent Americans, passed into the hands of Mexican owners. On taking charge of the business I found on hand a large amount of ore assaying 35 grams of gold per metric ton (about 1 oz. Troy per ton of 2000 lbs.); but the company was losing money, and was about to abandon the business.amalgamation

Obviously, the difficulty lay in the treatment of the ore. The extraction of gold scarcely reached one-tenth of the assay- value; the loss of mercury was considerable; and high freight charges excluded the alternative of exporting the ores.

This situation naturally suggested that amalgamation was not applicable to these ores, and that a more appropriate method must be adopted.

The ….Read more

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