THE INTRODUCTION OF WET CRUSHING.

Auckland Star, Volume XXVIII, Issue 299, 24 December 1897, Page 4

THE INTRODUCTION OF WET CRUSHING.

Of all the events of the past year relating to the progress and development of ohr goldfields, by far the most important is the successful introduction of wet crushing for the treatment of the bullion ores of the Hauraki goldfields.

After months of laborious experiment conducted at great cost, Mr Daw, general manager of the New Zealand Crown mine, has alTlast demonstrated the fact that the bullion ores of Ohinemuri can be successfully treated by wet crushing, and at the present time the whole of the output of his mine is being treated by this process at the Company's 40-stamp mill at Karangahake. The ore is crushed with cyanide solution in the mortars, from which the pulp is conducted directly to the leaching vats. The slimes are separated from the sands, and the cyanide solution from the slimes by simple automatically-working mechanical appliances, devised by Mr Daw. The essential feature of the process is the slime treatment, the particulars of which have not yet been made public. The advantages of wet crushing are : (a) a greatly increased duty of the stamps; (b) a saving of the labour and fuel for drying the ore ; and (c) a freedom from the pernicious dust nuisance. The natural and immediate effect of these advantages is a great reduction in the cost of treating the ore, which is accompanied by the installation of more healthful conditions for the workmen. *

The value of this new departure can hardly be over-estimated. "V. ith crushing and direct cyanide treatment the cost was too great to permit the handling of ores having a value under 30s per ton, but with wet crushing these ores, of which large leserves exist in many of the Ohinemuri mines, can be made to yield a fair margin of profit. During the coming year we shall probably see many dry crushing mills adopt the wet treatment'so successfully initiated by Mr Daw at the Crown mines.