Filtration of Fines & Slimes

The nature of slimes handled in the treatment of gold- and silver-ores has been discussed in technical literature to a considerable extent. The subject of slime-filtration from the practical worker’s standpoint has also received much comment, and scattered through the literature of the subject are descriptions of many slime-filtration installations. Articles of this nature serve […]

How Particle Size Affects Flotation

There is a marked particle size effect on both R and K. Table V gives an example of increasingly finer grinds in flotation with a different sulfide ore blend. Within the times of grind indicated, there is a tendency for both the over-all R and K values to increase with finer grind [see also Table […]

Grindability of Various Ores

During the last few years, one of the great problems in the milling of all ores has been that of grinding. This subject involves not merely the cost of the operation, but also the selection of the proper degree and character of grinding to yield the best metallurgical results on the given ore. Considering the […]

How to Track & Control Metallurgy using Charts & Graphs

The graphic methods and records described in this article have been developed, with satisfactory results, for the use of executives of the Chino Copper Co., in Hurley,. N. Mex. Particular attention is directed to the use of large wall-charts, the quick reference display of large charts, the scale notation of metallurgical charts shown in Fig. […]

Fine Gold Recovery & Refining

How to Remove Copper from Fine Gold Prevention of copper entering the final bullion has been the principal objective of all experimental work performed on zinc slimes in the goldroom. Above all other metals encountered during treatment, it is the most difficult to separate from gold and silver. Broadly, two methods are possible for elimination […]

Precious Metal Refinery Procedures

Recovery of Metals from Mattes and Slags Long ago, mattes and slags, which were the end products of the matte smelting process described in Part I, were sent to Port Kembla for final recovery of their metal content. Approximately 15 tons of slag and eight tons of matte used to be shipped yearly. Shortage of […]

Gold Refinery Procedures

Before processing by the gold refinery, gold can be extracted from ore by the following series of operations: Coarse crushing; Fine grinding; Straking for free gold; Flotation; Concentrate roasting; Straking for free, gold; Cyanidation of concentrates; Precipitation of gold from cyanide solution. The last operation is performed in a Merrill-Crowe radial leaf type precipitator, to […]

Fire Assaying History

The beginning history of fire assaying can be traced to the finds in Troy II (about 2600 B.C.) and in the Cappadocian Tablets (2250-1950 B.C.). These finds prove that very pure silver was made in the twenty-fifth century B.C. From this evidence we must conclude that the cupellation process, and therefore fire assaying, was invented […]

Grinding Media Wear Rate Calculation in Ball Mill

In the previous discussion the fact was established that the work done by a ball when it strikes at the end of its parabolic path is proportional to its weight and velocity; then, since the velocity may be considered as constant for all the balls in the mill, the work done by a ball is […]

Assaying

Assaying for ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, gold is performed by fire assay. This ancient form of quantitative chemical analysis by which metals are separated and determined in ores and metallurgical products with the aid of heat and dry reagents. At present, this technique is used principally to preconcentrate the noble metals from […]