Geologists query N.Z. technical ability

Press, 14 August 1980, Page 17

Geologists query N.Z. technical ability

The industrial revolution could still be stalled, however,. by the coal itself. Mining geologists — and ultimately the Government — have yet to be convinced that the coal can be mined economically and converted into liquid fuels in an efficient and commercially viable venture.

These doubts were highlighted at a seminar in Wellington in June, and one Government geologist’s views sent disturbing ripples through the country. Fred Bowen, a senior geologist, with the Geological Survey in Auckland, told the seminar that only about 0.1 per cent of the potential resources could be classified as minable, using existing technology in New Zealand.

Another geologist believed a major breakthrough would be needed in mining technology before recovery of the Southland deposits could be considered economic.

The technology may be available in West Germany, but it would not solve all the problems developers will face in Southland. Open cast mines 300 metres deep have been excavated in West Germany to recover lignite from seams between 50m and 100 m wide. Southland seams are very narrow by comparison, making open-cast stripping at depths of 300 m a difficult proposition.

A question mark remains over the economics of scraping out a coal that is sunk beneath a high

water table, under fertile land that already produces about 20 per cent of New Zealand’s export earnings. The problem of balancing farm earnings against coal mining will be decided largely by the ability to convert that coal into oils which can then reduce a staggering imported oil bill. It is a question mainly of national economics, although uncertainty still surrounds the conversion of lignite to liquid fuels. Huge undertakings in West Germany and South Africa use a process’ developed by the South African oil company, Sasol, but this is regarded as a wasteful process made viable by the economics of large-scale operations. Other processes are being developed, but

they have not been proved outside the laboratory or proved on a commercial scale.

The problem of mining a water-sodden coal, however, is a technical one outside the politicians’ realm. Water will make the mining operation more difficult and expensive. It is a problem, nonetheless, that the Government may be able to stave off for another five or / 10 years (i.e., into the late 19905), if deposits in Central Otago realise their early promise.

Compared with the Southland reserves, seams near Roxburgh would be easier to . mine and they present a more attractive proposition, according to Barry Douglas, of the Otago University’s geology department.

As a scientific officer with the department, contracted to the N.Z. Research and Development Committee, Douglas has studied test drills sunk in Central Otago in 1978 and 1979.

He has looked at four deposits, all of which he believes should be thoroughly investigated before any commitment is made on mining lignite in Southland.

Roxburgh is the most promising deposit, but with 280 million tonnes (inferred reserves), it is not the biggest. Hawkdun, in the North Idaburn . recontains possibly 450 M tonnes, and Homehills, nearby, may have 240 M tonnes.

A small deposit has been found in the Nevis region, better known perhaps for its shale and gold

deposits. The Southland and Vincent County Councils are pushing for a serious Government investigation into the Nevis mineral and coal deposits. Roxburgh’s advantage, Barry Douglas , says, is that virtually all the coal could be recovered. It lies in seams about 45m thick under less valuable farming land than the Mataura, Waimumu, or Croydon deposits in Southland. There would also be little problem with water. Opencast stripping, then, would be relatively simple, and rehabilitation of the land easier, he believes. - It is arguable that the greatest loss would be the Roxburgh race course, a popular attraction for picknicking punters once .or twice a year. The course lies directly over the Roxbugh East deposit.

Gold deposits would also make mining more attractive.

The, Roxburgh seams need more drilling, according to Barry Douglas, to get more information about the quality and properties of the coal. “We would know a lot more if the Mine Division had been more competent and had used fully Govern-ment-funded geologists,” he says. Test-drilling for lignite was done by a private contractor, who “went out knowing virtually little of what they were supposed to do.”

“We could have gained a lot more information on the Central Otago 1 coals for the same amount of money just through better data collected,” he says. Mr Douglas advocates a major restructuring of

exploration management to get ■ better value for money.

His suggestion ■is supported by Professor Mick Biickenham, of Otago University’s resurrected School of Mines. Professor Buckenham says there is a lack of mining geologists in New Zealand, and the lignite investigation will be seriously hampered by the shortage. A shortage of mining geologists will only sen the lack of information on the lignite deposits. Farmers, local councils, even the industrial developers and mining companies, will find information slow until sufficient qualified geologists are attracted back to New Zealand.