TREATMENT OF PYRITES.

Inangahua Times, Volume II, Issue II, 4 November 1881, Page 2

TREATMENT OF PYRITES.

» It is pretty geuerally admitted that, in the absence of effective appliances for the thorough extraction of tjold from the quartz, as much of the precious metal is i thrown away as there is recovered. Ibis would at 6rst seem a rather exaggerate I ( statement, but the result of assays and the yield obtained from pyrites when ores ' are treated in a seieotific manner prove ' beyond doubt that for every ounce of gold ' recovered by the stampers nt Jeast ( auother ounce, or its equivalent in chemN | cal products, is altogether wasted. More than one royal commission has already | reported to this effect, ac>l recomroen-h- < lions have repeatedly been rmde for Uie establishment of large central works for I ibe thorough treatment cf pyrites, and !

the whole of the waste products thereof, as tending to benefit the colony in every respect: The most potent objection to the carrying on of sucb works near a populous neighborbood is that of injury to public heaVb, but the thorough and approved scientific system upon which py iies bate of late years been treated in Eneland would seem to have completely allayed all fear on that score. Tbe fumes given o£f in the process of roasting pyrites are no^V condensed for tbe purpose of sarinsr the sulphur and arsenic, two by-prodoc's for vhich there is always a demand, Bnd which add grpatly to the profitable re* turns from the work. The Victoria Pyrifes and General Sm?ltinu Company, recently formed, have porcbased an eligible site nt Yarrnrflle, and are now completing their extensive work 1 * for the treatment of pyrites an<l general smeltin.'. A considerable sura of money has already been spen f over them, an J in the course of a fortnight the company expect to be in a position to commence operations Tbe works appear to have been designed on thoroughly scientific principles, and from tests made by Mr Cosmo Newbery it is said that the process to be employed will give better results than any other pro* cess which depends on amalgamation. It is not intended here to enter info a de* tailed description of the process, but simply to sketch cut the appearance of tbe works as they will be found on a visit to the establishment. Tbe property consists of about 13 acres of land, situated on the Yarra, just below tbe sngarworks, and has a frontage of 400 feet to tbe river. A jetty funning out into the river is to re« ceive the ores coming by water, whilst those forwarded by rail are received at an eDtrance communicating with the main road. Entering through the gate the first portion of the premises lo attract at* tention is the receiving bins, where tbe various ores are stored awaiting treatment, and what is termed the arising flour. The bins are capable of holding about 1200 tons of pyrites, aad at tbe present time they contain a large quantity of ores brought from various parts of tbe colony, which are lo be submitted for treatment as soon as operations cm be commenced. With the present plant the company only undertake to treat pyrites at the rote of 60 ton 9 per week, and to extract gold and by-products to within 10 per cent, of tue chemical ass;iy. There is a testing room attached to the works where samples of all ores can be treated and the percentage ascertained of what gold, silver, uuMraony, sulphur, arsenic and cobalt they contain. Passing from the bins, we com? to a large oxidising furnnce, in which tbe ores are roa9tpd. and in which the gas is generated. This furnace is a very powerful one, and is built on en incline. Tbe material is j>sUre<i 'Q f rora f he top, and gradually tfSWff-^oirn 8«~Tl"ls"snl)m«tted to the action of the beat. As tbe eas generates it passes aloii? 8 system of flue« 700 feet in extent until it rrachps iv another portion of the building an ncid ch>»m'>er. where it berimes converted into sulphuric acid. Tbe flues, as they convey tbp gas, and as the gas grows cooler, gradually diminish in size. All sulpurous ores carry arsenic, and as this chfrnieal passes along tbe flues with the gas it drop? down and bargs to tbe sides like icicles, from where it ran be easily collected by means of aperturps let into tbe flies for that purpose at convenient places along tbe route. The acid chamber, or rather chambers— -for there are two compartments—are quite a feature of the works, l'ho first receives the gas after it has completed its journey along the flues, and is then eliminated from any remaining quantity of arsenic it may possess. Thus relieved of the atsenie, it passes into a second chamber o\ huge proportions, wherj it is by a certain process converted into and collected ss sulphuric acid. In addition to the oxidising furnaces there are, of course, separate furnaces for smelting gold and other meials. Tlk* enpine to drive the machinery is of 150 horse power, with 25£ inch cylinders. There is a!so in convenient proximity a five-bead stamp battery and other appliances necessary to smelting ; and in ad respects tbe establishment sc-tns to be replete with every requirement for carrying; on the operations o' the company.