Precious Metals

Hydraulic Sluicing

Supposing that a claim is suitable for hydraulic sluicing, the first thing to do would be to ascertain what is the probable volume and pressure of the water supply. This can be closely approximated by means of an aneroid survey. The facilities for the disposal of the tailings should next be ascertained. As mentioned before, … Read more

Effect of Silver on Chlorination & Bromination of Gold

When dry chlorine gas is made to act in the cold upon finely- divided gold, it converts the latter with evolution of heat into auro-auric chloride, Au2Cl4, a hard, dark-red, hygroscopic salt. Moisture splits this salt into aurous and auric chloride, Au2Cl4 = AuCl + AuCl3 ; treatment with water converts it into auric chloride … Read more

Vanning Buddle Concentrator

I tested an ore, which was peculiarly difficult to treat, on several concentrators then in general use, including the Frue-vanner, the Luhrig table and the Cornish buddle. Owing to the character of the ore it had to be crushed- to a very fine state of division, and the results obtained were far from satisfactory; a … Read more

Free Milling Gold Laboratory Testing

Friends often ask how accurate the work of our little stamp-mill is, or express the opinion that a little mill cannot do good work. As a reply we would like to place on record the results of a few tests. There are two periods of work in our laboratory; the fall term, when the class … Read more

Precipitate Gold Mercury with Electricity

The treatment of slimes has of late years been, the chief difficulty in connection with cyanide work, in which much time and money has been spent in endeavouring to find a practical solution of this problem. The processes at present in use are: Filter pressing, as practised in Western Australia. Decantation, as practised in South … Read more

Effect of Tellurium on Brass

The presence of small amounts of tellurium in certain kinds of copper, and its exceptionally deleterious influence in producing red-shortness of this metal, led the author to conduct a few experiments on the influence of tellurium on the properties of brass. While these experiments were not intended to be exhaustive, they demonstrate that, as far … Read more

Assaying Silver Bullion

The apparatus which I shall describe in this paper has been in use for some time at the Silver Bullion Assay laboratory of the Pennsylvania Lead Company’s works, and has been found to give good results, and to be simple and convenient. Steam Bath.—This steam bath is shown by Figs. 1, 2, 3, and 4. … Read more

Silver Lead Bullion Sampling

Several interesting experiments were made in the sampling of the silver-lead bullion obtained from the water- jacket smelting-furnace. The smelting-plant is divided into two portions, known locally as the north furnaces and the south furnaces. The former group comprises nine and the latter six 80-ton water-jacket furnaces, besides which the south group has one small furnace used … Read more

Volatilization of Silver Ore: Chloridizing Roasting

The latest revised edition of Mr. C. A. Stetefeldt’s book on the Lixiviation of Silver-Ores, which appeared very recently, contains no mention of the volatilization of silver in chloritization-roasting—an omission which is the more remarkable in view of the fact that in former editions of the work this important subject was noticed. Moreover, Mr. Stetefeldt … Read more

Cyanide Chemistry & Gold Extraction

The fact that many millions of gold have been extracted by the cyanide process, during the last five or six years, from South African tailings which could not be profitably worked by any other method previously tried upon them, lends a peculiar practical interest to this branch of metallurgy. Numerous writers have recently made valuable … Read more