C. -3

96

Homeward Bound Quartz-mine. —(15/12/99): On this property two men are driving a crosscut by contract. Minerva.— (2/4/1900) : In consequence of the flume section of water-race being broken away operations are suspended. Garden Gully Quartz-mine. —Work has ceased since Christmas. Boaring Meg Quartz-mine. —Work ceased at Christmas. (2/4/1900): Still idle. Venervia Quartz-mine. —(2/4/1900) : Stephen and Boyle are driving a crosscut from main winze. Jtdian Quartz-mine. —(18/8/99) : This mine ceased work in May last. The company made application to the Mines Department for subsidy to enable them to drive a low-level tunnel, but the proposed tunnel was considered impracticable. Keep-it-Dark Mine : Description op Plant and Treatment of Ore. The battery is connected with the mine by a short level tramway. It consists of twenty heads of stamps, each 7501b. in weight, with boxes of the latest design. The ore is crushed through punched gratings, having 225 holes per square inch, and passed over three sets of copper plates, on which the greater portion of the gold is saved. Leading from the battery, the tailings are run in a chute to the elevator-wheel, and lifted 15 ft. so as to flow into the cyanide-vats, where they are saved and treated. The sand is distributed in the vats by automatic distributers, and the slimy overflow is concentrated by running over canvas slime-tables. The cyanide plant was completed in April, 1899, and consists of six steel leaching-vats 22 ft. 6 in. diameter by 5 ft. deep, with three steel sumps, one 18 ft. diameter and two 13 ft. 6 in. diameter, each 4 ft. in depth. There are two zinc-extractor boxes 12 ft. 6 in. in length, with ten divisions each, made of kauri, having side discharge-launders for cleaning up the gold-slimes. The leaching-vats are fitted with filter-beds and central discharge-doors, which slope 3 in. towards the centre. Each vat takes about forty hours to fill from the battery, after which the sand is drained, and treated with cyanide until the gold is extracted. After washing, the tank is discharged by sluicing, which can be done in three hours. The whole operation of filling, treating, and discharging takes about nine days. There are three different strengths of cyanide solutions used, which are varied according to the quality and nature of the ore under treatment, the average consumption of cyanide being about 2 lb. and of zinc 3 lb. per ton of tailings treated. In connection with the plant is a complete assay- and melting-house, where regular assays are made of the ore during its course of treatment. From April, 1899, to 31st March, 1900, the battery crushed 9,100 tons of ore, which yielded 2,495 oz. 7 dwt. 9gr. of gold, equal to about 5f dwt. per ton. During the same period 7,550 tons of tailings, including 900 tons accumulated, were treated with cyanide, which yielded 1,681 oz. 13 dwt. 4gr. of bullion, valued at £5,461 Bs. 7d., or equal to about 14s. 4d. per ton. Alpine Cyanide Plant. Messrs. Aitken and Kingswell, having purchased the Alpine Company's accumulated tailings for the sum of £555, together with a four-years option on all tailings produced, at the rate of Is. per ton on crushed quartz from the mine, erected the above-named plant in March, 1899, at a cost of £1,500, with a working-capacity of 1,000 tons a month of eight days' treatment. Mr. Aitken (who designed and supervises the Keep-it-Dark and Alpine plants) constructed the four leachingvats and zinc-extractor boxes of equal dimensions on both properties, the two sumps being 20 ft. and 15 ft. diameter respectively by 3 ft. in depth. The crushed ore leaving the stamps is passed over copper plates and blanket-tables. The blanket-washings are afterwards treated by berdans. The tailings then pass to the cyanide-well, and are elevated by a blow-up jet-pump into long buddies, thence trucked to the leaching-vats. After treatment the waste sands are sluiced through side discharge-doors. Practically the cyanide plant is idle in consequence of crushing operations being discontinued, owing to the unpayable quality of the mine-ore. However, there is little doubt that if the cyaniding and crushing were worked as one concern the company could utilise the low-grade ores more effectively, as the tailings treated direct from the copper plates would enhance the cyanide gold output, and dispense with the use of blankets and berdans; also a considerable saving would be effected in the management expenses. During the year 9,630 tons of tailings was treated, which yielded a gold-value of £4,294 12s. 2d.; average value per ton, 10s. Considering the accumulated tailings were chiefly produced from low-grade ores, the returns are payable and satisfactory. General Remarks. The gold output shows an increase of £28,886 2s. 2d. over the preceding year. Reviewing the productiveness of the gold-producers, together with the extensive and successful mining developments that have steadily been pushed forward to a final issue in the Golden Fleece and New Inkerman Mines, it may be anticipated that, with the additional crushing-power and gold-saving appliances now being erected on these properties and at the Progress Mines, the gold output for the ensuing year should be marked with a substantial increase over the past. Accidents and Fatalities. Progress Mines, Beefton. —(28/4/99): A miner named Christopher Kassler was found dead in a winze between Nos. 5 and 6 levels. Dr. Conlon's evidence showed death was due to heartdisease. Hercules Quartz-mine, Beefton. —(13/11/99): A miner named Thomas Martin was killed by falling down a ladder-way between Nos. 6 and 7 levels when leaving his work at " knock off."