History: Cement manufacture in Golden Bay, a snapshot in time

BY ROBYN PARKES

In 1907 great interest was generated in the deposits of limestone and clay at Golden Bay. A company of Wellington and Nelson businessmen was formed and registered to work the limestone and clay deposits on the coast at Tarakohe and Pōhara.

A visiting Danish expert made an exhaustive inspection of the raw materials with very satisfactory results. A site for a wharf to enable shipments from the works at any stage of the tide was selected.

By early 1912 the works had been underway for some months and an extensive description was provided. Located on the seacoast about seven miles from Tākaka, Tarakohe could be reached either by a steamer calling three times a week from Nelson, or by road from Motupipi along the Pōhara beach, then by road over the hill leading to Ligar Bay.

The latter part of the road was steep for a horse and vehicle, so a road along the seashore at the foot of the limestone cliffs between Pōhara and Tarakohe was in the process of being formed, and when completed would cut the distance down and eliminate climbing the steep hill.

Near the works, a township sprang up with scattered huts and tents and several corrugated iron structures where many of the staff lived. The works consisted of huge, corrugated iron-covered buildings, with three tall chimney stacks.

Alongside the works were hundreds of thousands of tons of limestone and marl (essential in the manufacture of cement). Two quarries had been opened with the limestone right alongside the stone crusher and the marl quarry located a short distance away up the hillside, and connected with the works by a gravity tramway, meaning the loaded trucks in their descent pulled the empty ones back to the working face.

The limestone from the quarry was carried and deposited by trucks up to and into the crusher with the right proportion of marl. The crusher was driven by a 50 h.p. motor and had a daily capacity of between 200 to 300 yards of stone.

When crushed to the right size, the mixed limestone and marl was lifted to the storage bins and led by conveyors to the drier, a large, long cylinder, where the moisture was extracted by heat. The dried material was then sent up by means of chain and bucket elevators to more storage bins, where it is fed to the mills and ground to the necessary fineness.

There were three mills, two ball mills and one large tube mill. The ‘raw meal’ was conveyed and fed into a rotary kiln, where it was burnt to ‘clinker’ (the backbone of the cement) at between 2000 to 3000 degrees Fahrenheit.

From the kiln, the clinker was passed through a cooling cylinder and transferred to the finishing mills. The resulting product was ‘Portland cement’. This was transferred on conveyors and elevators to the storage bins, which had a capacity of 3000 tons.

The cement then passed to the packing room, where it was bagged by automatic bag-filling and weighing machines and stacked ready to be shipped from the wharf.

The powerhouse contained the latest in steam and electrical machinery with the whole of the works run by electrically. The chimney stack of the powerhouse was 137 feet high and was self-supporting.

The works had a capacity of about eighty tons a day, and around 100 men employed in various jobs.

In one-week, mid-February 1912 some 700 tons of cement were shipped away, with a steadily increasing demand for the Tarakohe product.