H1ST0EICAL NOTES: MIXING, METALLURGICAL A>"D STATISTICAL. 39 OTHER CHEMICAL PROCESSES.
The Hunt and Douglas process was successfully applied in 18S0 to the ores of the Conrad Hill mine, X. C. The roasted sulphurets were leached with a ferrous chloride solution, converting the copper to a soluble chloride, from which it was precipitated as metallic cement on scrap iron.
The Designolle process, which consisted in treating the roasted ore with corrosive sublimate in iron vessels, was only moderately successful in its application, for the reason that it made a very base bullion, the iron of the apparatus invariably precipitating any soluble salts formed in the roasting. It was worked for a time, during j 882-83, at a custom plant near Charlotte, X. C.; at the !N"ew Discovery mine, Rowan county, ST. C. (18S3), and at the Haile mine,1 S. C. (1883).
A plant for the extraction of gold from pyritic concentrates, with the recovery of the sulphuric acid, was erected early in the present decade at Blacksburg, S. C, mainly for the treatment of custom ores. The concentrates were roasted in a 'Walker-Carter muffle furnace, which was connected with lead chambers. The amalgamation of the roasted product was carried on by a patent process known as the Caloric Reduction Company's process, the principle of which was a volatilization of mercury into the mass of the pulp, followed by a condensation of the same, the amalgam being led into settling vats. It wTas proposed to use the tailing residues for the manufacture of red paint. The scheme, as might have been predicted, was a failure. A similar process, known as the Phelps process, had already been unsuccessfully tried on ISTorth Carolina ores, in (about) 1877, in an experimental plant situated at Philadelphia.
Attempts at pyritic smelting were made as early as 1847 at the Vaucluse mine in Virginia by Commodore Stockton, but resulted in failure.
Matte smelting, followed by refining in reverberatory furnaces, was practiced (about 1881-1882) on the copper ores of the Conrad Hill and the Xorth State mines in Xorth Carolina.
Experiments on matting auriferous sulphurets from the Haile mine, S. C, were made in 1S86 by Mr. E. G. Spilsbury,2 but proved unsuccessful.
Eegarding smelting processes in the South, probably most has been done in the attempted treatment of the complex galena-blende ores, carrying silver and gold, of the Silver Hill and Silver Valley mines, Davidson county, X. C.
The process in use at Silver Hill, as early as 1853, was heap-roasting, followed by wet-crushing in a stamp battery, the zinc oxide being dis-
1 Trans. Amer. Inst. Min. Engs., vol. xv, p. 771.
- Trans. Amer. [nut. Min. Engs., vol. xv, pp. 767-775.