PRECIPITATION,
and is then conducted through a system of boxes filled with scrap iron, thus precipitating the copper.
The richer copper liquors which have been drawn from the tanks fire not allowed to run in with that which comes from the dump heaps. This liquor is also run into settling tanks, and from them pumped into four large barrels, mounted horizontally on friction rollers, to which a very slow motion is given. These barrels are 18 feet long and six feet six inches deep outside measure. They are built very strongly, and are water-tight. Ten tons of scrap iron are always kept in each of these barrels, which are refilled six times daily, complete precipitation being effected in less than four hours. Each barrel is provided with two safety valves, inserted in the heads, which open automatically to allow the escape of gas and steam. The precipitation of the copper in the barrels forms copper cement. This cement is discharged from the barrels on to screens which hold any lumps of scrap iron which may be discharged with the cement. It is then dried by steam, after which it is conveyed into another tank, left to cool, and then placed in bags ready for shipment, as copper cement. The building in which the liquor is treated is the mill part of the property, from which they send out 42 tons monthly of an average of 85 per cent, of copper cement, this being the average yield of the mine.
There are 23 white men and 40 Chinamen employed at the mine and the mill. There are also several wood choppers, etc., on the company's pay-roll. Eight months' supply of ore is always kept on hand, there now being 12,000 tons roasting. The mine is now paying regular monthly dividends, and everything argues well for the continuance of the same.