Slight Fall In Output Of C.R.A. Mines

Press, Volume CVIII, Issue 31585, 24 January 1968, Page 17

Slight Fall In Output Of C.R.A. Mines

SYDNEY, January 23. Conzinc Riotinto of Australia, Ltd, yesterday reported a slight drop in output of nearly all products by its two Broken Hill mines for the year to December.

The wholly-owned Zinc Corporation, Ltd, suffered a reduction in output over its whole range, and the 32-per-cent-owned New Broken Hill Consolidated produced less lead and silvei’ in spite of a record level of ore treatment.

The Zinc Corporation’s problems resulted from a alight drop in ore production for the year, coupled with a slight reduction in grades of ore treated. Total volume of ore treated for the period fell from I 875,117 tons in 1966 to 863,877 tons in 1967. Ore assay levels fell from 11.8 per cent lead to 11.5 per cent, from 3oz of silver a ton to 2.90 z and from 9.9 per cent zinc to 9.8 per cent. These reductions meant that I

I volume of lead concentrate (fell from 130,728 tons to j 125,866 tons, with reductions from 99,681 tons to 95,809 tons in lead metal production land from 2,231,4120 z of silver to 2,258,6780 z. I Zinc concentrate production iwas back from 148,550 tons Ito 146,437 tons, actual zinc metal output being down from 77,542 tons to 75,848 tons. New Broken Hill For New Broken Hill, the decline in ore values was far

more marked—but it was offset largely by a massive increase in volume of ore treated. Ore production from New Broken Hill’s mine rose from 839,363 tons to 959,753 tons—the closest yet to the planned new target of Im tons annually. But with this increase in output came a variation in ore quality. Instead of the 10.8 per cent lead assay obtained in 1966 the company gained only 9.3 per cent in 1967, and instead of the 2.90 z of silver contained in each ton of the 1966 ore, there was only 2.30 z in each ton last year. These reductions led to a cut in lead metal output from

• 87,491 tons to 85,440 tons and in silver a cut from 2,183,9580 z to 2,030,8250 z. However, the reduction in silver production is more than compensated by the lift in silver prices for the year. The company’s zinc production for the year rose as a result of an increase from 13.8 per cent ore to 14 per cent. This led to a lift from 108,194 tons to 126,774 tons in output of zinc metal by New Broken Hill,