How Chemistry Helped In Mining Development

Manawatu Times, Volume LVI, Issue 7067, 28 January 1933, Page 3

How Chemistry Helped In Mining Development

PRESIDENTIAL ADDRESS TO MEETING

The important part that chemistry has played in the development of the New Zealand mining industry was dealt with by Mr. W. Donovan, M.Sc.,

F.1.C., Dominion analyst, in his presidental address at the annual meeting

in Palmerston North of the New Zealand section of the Institute of Chemistry of Great Britain and Ireland.

“With lower costs now prevalent and with a premium on gold, the mining industry has received fresh stimulus. The future may lie in the treatment of low grado ores, and the trained chemist will be called in again to assist in the industry, which has considerably benefited by the application of chemistry," he said. “One can but wish that other primary industries in New Zealand of greater importance and value than gold mining would adopt the same favourable attitude as the mining industry to technical progress and Scientifically guided research. The results, I am convinced, would be equally beneficial,” ho added.

“That chemistry has played an important part in the development of the mining industry in New Zealand is due mainly to two things.—(l) The recognition of the older generation of mining men that flic processes they employed were often inefficient and were capable of improvement, and their eagerness to try other processes, even though unproved on a working scale. (2) The establishment in .1886 of schools of mines in mining centres to give even the rank and file of the workers mining and metallurgical knowledge. Credit must be given to Hon. W. J. M. Larnach, then Minister of Mines, for this step. The enthusiasm with which a preliminary series of lectures was given in the various gold fields by Professor J. G. Black and a staff of itinerant instructors can scarcely oc described. The knowledge imparted was appreciated and widely used. “The training in practical chemistry given at some of the schools of mines 30 years ago was in some respects up to and beyond the then University standard. The schools provided men trained to control, adapt and modify, if necessary, recognised metallurgical processes in the treatment of New Zealand ores. Gold mining steadily progressed until m 1906 the export of gold exceeded £2,000,000 in value. After that year it declined, aud for various reasons is now but little moic than a fourth of this figure, but the industry, has, as stated, received a fresh stimulus on account of prevailing conditions. “Mining in New Zealand is confined practically to two branches gold and coal. Borne 2,500,000 tons of coal are mined each year. The chemist plays little part in coal winning operations. He examines the mine air occasionally for the presence ot explosive and other dangerous gases. He determines the percentage of line inert matter in the dust on the roadways, which must exceed a definite figure so that minor explosions of gas at a working face will not be transmitted by the dust throughout the whole mine. He analyses coal from the various seams for mixed carbon, vola- ! tile hydro-carbons, water and ash, and determines calorific value. This indicates their range of usefulness and governs their sale. Having carried out these various operations, the work of the chemist relative to the winning and marketing of coal at the present time ceases.

"In the past some work was done on. the relative inflammabilities of New Zealand coals, which proved of assistance wheu safe-working measures were framed. Various investigations have dealt with the suitability of single coals and of blends for gas making, resulting in a large market being opened up for the bituminous coal in the gas industry. The possibility of the use of sub-bituminous coals for the manufacture of producer gas was dcmonsiratau by the workers at Canterbury College, but this field proved limited in scope. A study of low temperature carbonisation of sub-bituminous coal laid the foundation for the establishment of the carbonisation works at Eotowaro, near Huntly. It is hoped that a recently completed investigation on briquetting of slack coal will result in the establishment of suitable plants in more than one centre. "The industry has now, for financial reasons, withdrawn its support from research. Perhaps the chief and only service which the chemist can render the industry in New Zealand at the present time is to follow closely rue progress of research elsewhere, and interpret the results in the light of his knowledge of New Zealand coals and New Zealand conditions.

Gold mining at tho present lias an output only one quarter of the value of coal, being £519,000 for the year 1930. It was four times this in .1906. The chemist’s part in the industry is first to assay samples from working faces in the mine and determine the value of the ore in situ, so that worthless ore may be left in the mine, and only profitable ore broken out for treatment. Next by routine tests ho exercises a certain amount of control over extraction processes. Again, lie may he required to modify any specific method of treatment, or even to devise and try out new methods in special cases.

"Metals other than gold and silver are not mined extensively in New Zealand. With regard to mercury, a solvent process for the recovery of mercury iu cinnabar was investigated at the Dominion Laboratory in 1920, also the application of oil flotation to cinnabar ores demonstrated. The possibilities of flocculation, followed by oil flotation, would be worth considering in connection with the treatment of the mercury deposits at Kaikohe, which are in very wet clay and which nave not proved amenable to the usual furnace treatment. Work having relation to theories of ore deposition has been carried out from time to time.”