Quarrying & Mining Magazine
Quarrying

Dolomite from high on the hill

Dolomite is only mined commercially in this country on the Wakamarama Range, and Takaka-based Sollys has found a niche market supplying it to the fertiliser manufacturing industry. RICHARD SILCOCK explains.

Merv Solly, managing director of the Sollys group of companies, checks on the quality of the ground dolomite.

ABOUT FIVE KILOMETRES up a steep gravel road on the slopes of Mt Burnett, part of the Wakamarama Range to the south of Collingwood in Golden Bay, is where Sollys’ dolomite and lime quarry is found.

“It’s up where the keas are and the winter snowline,” says Merv Solly, managing director of Sollys Freight Services, Sollys Quarries and Golden Bay Dolomite.

Merv, now 71, has quarrying and transporting in his blood, having inherited the 90-year-old business from his father, who took over from its founder, Merv’s grandfather, Ken Solly.

Sollys operate two quarries; a 15-hectare dolomite quarry and a smaller two-hectare lime quarry. They have owned and operated the lime quarry since 1932, and the dolomite quarry, which is presently producing 85,000 tonnes per annum and is the only commercial dolomite mine in the country, for 10 years.

They also run a very successful freight and transporting business which operates from Takaka, Collingwood, Richmond, Blenheim and Christchurch, with a fleet of 70 Isuzu and Nissan trucks.

“We have been successful because we operate the business on the basis that good service and making the customer the first priority is essential,” says Merv.

“Since I left school I have been involved in the business. I’ve lived and worked in the Golden Bay area all my life and love it. I’ll never leave – I will keep on going until that end that comes to all of us eventually.”

Suffering a cancer scare a couple of years back, which he fortunately overcame, Merv says he lives each day with a passion for life and the business.

“My son Ed and my daughter Adele now run the day-to-day operations ably assisted by good managers and staff, while my role is more overarching and keeping an eye on profitability and how we might improve sales and efficiencies.

“We also look after the health and safety aspect which is at the very forefront of our whole operation.

“Health and safety is something we take pretty seriously, and I am not backward in bringing our guys into line where there may have been some complacency.

“In our type of business you can’t leave anything to chance, and we are pretty strict about that, especially with younger people coming on board.”

Apart from a fatal accident some years back, Sollys has an unblemished record for safety spanning 48 years.

The crushing plant that is used to crush the rock down to a fine 150 microns for use in fertilisers.

Most of the lime extraction is used for making calcium, which is used for agricultural fertilisers.

“Our throughput of lime averages around 1800 tonnes per annum and we deliver it to farmers in Golden Bay, and the Tasman and Marlborough districts.”

The dolomite quarry was previously owned by multinational Omya Inc, a leading supplier of minerals worldwide which owned over 128 hectares of land in the mountain range and mined the quarry. Before it a string of companies, including Golden Bay Cement and Nelson Lime and Marble, owned and operated the quarry.

The dolomite is extracted by first drilling and blasting, and then excavated using 25-tonne excavators. It is transported down the mountain in Volvo articulated dump trucks to Sollys crushing and processing plant which operates as Golden Bay Dolomite.

“At our plant we use a 36 x 24 jaw crusher and a 4FT cone crusher that we imported direct from China some time back, and they have proven to be very reliable with few mechanical problems,” says Merv.

The crushed rock is then processed through a series of Steadman cage mill screens producing chip from between 30mm and 150 microns, with the latter accounting for 66 percent of sales as the solubility is optimised.

“Because we are able to crush down to a very fine particle size it is without a doubt one of the contributing factors to the continued success of the mine.”

This smaller chip is mostly exported to Nufarm in Australia where it is used in the manufacture of fertilisers for agriculture purposes, particularly dairying, as it contains a high percentage of calcium carbonate and reduces the amount of supplementary feed required for stock, aiding overall stock health.

“We are sending around 700 to 800 tonnes each year to their plant in Geelong.”

Sollys has also been sending large quantities of dolomite rock to Wellington for use on the Transmission Gully Motorway (TG) project.

Due to its durability, size and shape, the rock is used in an uncrushed state to line specially constructed channels which will carry water from various streams that had to be diverted from the motorway alignment.

“This rock, what we call cap rock, comes from the top of the dolomite seam and is extremely hard,” says Merv.

“We’ve supplied TG with some 80,000 tonnes of rock over the last 18 months and have around another 10,000 tonnes to deliver. We load 2700 tonnes at a time onto a sea-going barge operated by Heron Construction which ships it across the Strait from Port Tarakohe here in Golden Bay to Wellington.”

Dolomite rock is often used as armour rock for coastal seawalls to stop erosion.

Dolomite rock has also been supplied for the Seaview Marina in Petone and for constructing a flood protection wall along a part of the Hutt River in Lower Hutt.

Merv estimates there are still millions of tonnes of dolomite to mine from the seam high on the Wakamarama Range, which runs to a depth of 280 metres and is approximately 450 metres long.

Asked what is unusual about their quarrying operation, Merv says it is the location.

“It’s a pretty inaccessible place, and apart from the road which we maintain, there is no other way of reaching the quarries.

“Due to high rainfall in the area, we seldom have to damp down dust with water carts, other than a few times over the summer, so it is a pretty clean operation.”

The 12 bench dolomite quarry which has been mined to a depth of 144 metres is rehabilitated with the planting of native species as Sollys progressively works along the seam.

“We are pretty environmentally conscious and aim to leave the mined areas as we found them prior to extraction.”

Merv recently returned from attending a conference at Missouri University in the USA on soil science and the use of dolomite.

“The conference centred on the work of Dr William A. Albrecht, a former emeritus professor at the university and a foremost authority on soil fertility and the connection between soil quality, animal health, food quality and ultimately human health.

“For our quarry operation, I see a future in the continued expansion of our dolomite extraction and increasing our export sales of finely ground dolomite for the agriculture sector to something like 60,000 tonnes per annum.

“After all and to quote Dr Albrecht, you have to have a vision.”

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