Extracts from "Historic Features of Union Hill Waihi" 2004 E. Lens


There is considerable confusion in the literature regarding the early history of mining in Waihi. It is my contention that the battery on Union Hill was never called the "Union Battery"!

Two batteries were built more or less concurrently in 1882, the "Martha" on the eastern side of Martha Hill, the other ("Manukau" Jones’) on the Ohinemuri River near the present Victoria Street Bridge. This Ohinemuri River battery may have briefly been called the "Waihi Battery", but was soon combined with the Martha Battery which was brought down from Martha Hill (because it had problems with water supply volume or head).

So, the battery at the Ohinemuri became known as the "Martha Battery", and was the only one operating in the Waihi district until approximately 1888.

In 1890 the Martha Battery (and the Martha Company's mine) were purchased by Thomas H. Russell, and ownership was transferred to the Waihi Gold Mining Company. The battery was surplus to requirements, and sold to the Silverton Company, who remodelled it, and renamed it the "Silverton Battery".

In due course (1898), the Silverton Company was bought by the Union-Waihi Company, who renamed the battery: "Union Battery". The Union-Waihi Company sent ore to this battery from 1899 to 1901.

The Waihi Gold Mining Company took over the Union-Waihi Company in 1901, and closed the "Union Battery" in 1911.

Despite latter day confusion, the battery built in 1888 on Union Hill was never called the "Union Battery", but always the "Waihi Battery", or "Waihi Mill". There was no battery on Union Hill prior to the Waihi Battery. It was built by the Waihi Gold-and Silver-Mining Company, or Waihi Gold Mining Company, as it was known, to treat their ore from the Union Hill area (Union, Rosemont, Amaranth and Winner mines). This company acquired the Martha mine in 1890. (The Waihi Gold Mining Company was established in December 1887, and became the Martha Gold Mining Company in 1935.)

The "Waihi Battery" started with Globe crushers, replaced by 30 head of stampers, then expanded to 60 head, and in 1894 to 90 head. The cyanide process was fully adopted in 1894.

The Victoria Battery at Waikino commenced crushing in 1898, and by 1902 the Waihi Gold Mining Company had 330 head of stamps crushing Martha ore (Waihi: 90, Union: 40, Victoria: 200).

The Waihi Battery was closed in 1913, though the Melthouse and Refinery at this site continued in use until closure in 1953.

Confusion also surrounds the people called Russell: Thomas, Thomas Henry (TH), and James.

Union Hill has three main owners: Land Information New Zealand, Newmont Waihi Operations (Waihi Gold Company), and Department of Conservation.

Waihi Mill

Date: of construction 1888; ceased operation 1913 - 14.

The Globe crushers erected in 1888 were soon replaced with 30 head of stamps. 1891 saw an additional 30 head installed, with pan amalgamation replaced by the full adoption of the cyanide process in 1894. Thirty more stamps brought the battery up to 90 head in 1895. Dry crushing ceased in 1902, and tube mills were introduced in 1904 (eventually five). Six air-agitation tanks were built during 1909-10 (I believe these to be the only air-agitation tanks to be built of concrete, and the only air-agitation tanks still in existence today).

At 60 stamps, the battery was the largest in New Zealand at the time; likewise with 90.

1895 Mines Statement: In order to treat this ore a gigantic plant is, of course, requisite, and, although that belonging to the company is the largest in the colony, it is now being increased by thirty head of stamps; and a fresh cyanide plant and additional kilns have also been constructed, and others are in course of construction.

Remains: kilns, air agitation tanks, tall masonry walls, concrete walls and floors, massive machine mounts, tube-mill floor, possible hopper and stone-breaker foundations, stamper mortar timber and concrete foundations, engine room, Pelton wheel shaft, and more.

Waihi Mill Background.

The Waihi Mill as seen from the No.1 Shaft on Martha Hill.
The Waihi Mill as seen from the No.1 Shaft on Martha Hill. Note the tramway from Martha, extreme left, the ore kiln roofs (smoke drifting to left), and the New No. 1 Shaft poppet and buildings (firewood is stacked along tramway to left). Centre are the stamper buildings, engine and boiler houses, and to the right can be seen the Mill Stream flume crossing the gully. Notice also the cottages behind the flume (near Chappell’s Shaft), and the No.2 Drive portal above and to the right of them. (photo c. 1896) WACMA

The ores of the Waihi District (and Karangahake) were refractory in nature, with high silver content, and did not yield much more than 25% of their value to the traditional battery process (wet stamping and plate amalgamation with mercury). The Martha battery on the Ohinemuri, treating mainly Martha ore, was such a battery, struggling to cover costs. The "low grade" ore of Martha was later discovered to be simply "low recovery".

1886 Mines Statement: The outlying hills of this district [ie other than Martha – E] remained unoccupied till Mr. La Monte’s process drew attention to the possibility of their containing silver; and about the end of last year the ground was taken up and tested, with the result that three of these hills have now been proved to contain rich ore, and great hopes are entertained of the others. The silver contained in this ore is principally in the form of sulphides, and the recent smelting-furnace trial at the Thames has proved these ores or rock (unlike galena and ironstone) are not well adapted for smelting. They contain such a percentage of silica (90 to 95 per cent.) that the quantity of fluxes necessary for the process is overwhelming. The question therefore remains what is the best method to save this fine gold and finer silver.

The Union Gold-mining Company, mining on Union Hill, had parcels of ore sent to the Martha Battery, and overseas. Though little was recovered by the "ordinary battery process" at the Martha Battery, analysis of the ore both in New Zealand and overseas confirmed that the ore was nevertheless very rich (66oz. of gold and 186oz. of silver to the ton was one report).

In the 1887 Mines Statement, the inspecting engineer had this to say: In any case it is very useless for the miners to mill such ores as are represented by the samples submitted by the ordinary wet stamper-mill. They should be—first, spalled (i.e., broken and sorted); second, calcined; third, crushed and amalgamated with cyanide; fourth, the residue should be buddled and treated chemically, or, better still, sold on assay for export to where metallurgical works are established.

The loss in crushing this class of ore with the ordinary battery-process is something enormous. When the stone is rich in silver not more than 20 per cent of the bullion is saved, the whole of the silver being carried away with the water. It is quite disheartening to the owners of these claims to know that they have a valuable property, and cannot extract the metals from the ore. They are now making themselves acquainted with the mode of assaying and ascertaining its value, but are yet unable to get a cheap method of treatment.

Waihi Mill, c. 1903.
Waihi Mill, c. 1903. The large two storey building left centre is the Vanner Shed, Boilerhouse is centre right. Note large tiphead to right of New Shaft (top centre), and the tailings and tailings flume in the foreground. DoC

It appears that assaying to determine the value of the ore was not commonly practised, and the losses by the "ordinary battery process" were not understood (would you wish to advertise that your mill was discharging 60 to 75% of the bullion into the river with the tailings?).

1893 Mines Statement: The same stereotypical answer was always got from the mine-manager when inquiries were made as to the saving of the gold at the battery, "They were losing very little, and they looked on their gold-saving appliances as being as good as any in the district."

The creation of a new company, the Waihi Gold Mining Company in 1887, and the wish to establish a profitable method of treating their ore, saw the erection of the first mill on Union Hill.

The samples of ore had been sent overseas to England and America, partly to determine a method of treatment for these refractory ores, high in silver content. As a result, a completely new method of treatment was going to be attempted in the Waihi Mill. The company, having decided on dry crushing and hot pan amalgamation, had to set about drying and roasting the ore preliminary to crushing, and then crush dry to a very fine degree. Both these procedures were untried in New Zealand. They were to pioneer these processes.

1888 Mines Statement: This company's mine, together with the Rosemont and Winner Mines, have been purchased by an English company, and machinery for treating the ore is now in course of transit to the ground. Mr. J. W. Walker, the manager of the new company, has recently visited some of the mining centres in America to see the principle on which similar ores are treated there. From what I can learn, the treatment of ore will be by roasting, afterwards crushing it in a stone-breaker, and Globe crusher; thence to amalgamating pans and settlers, where it will be chemically treated.

Waihi Mill c.1890.
Waihi Mill c.1890. Several long buildings, centre left, are the Vat House, above and beyond them are the kilns. Centre is the Old Shaft poppet head, with the ore lift to its left. The stampers are housed in the big buildings to the right of the shaft. To the right of them the Engine House, then Boiler House. DoC/WACMA

This was the Washoe process (as used by Mr Railey at Karangahake) with dry crushing, and in time the plant was able to achieve a recovery of about 65% of the gold and 35% of the silver in the ore; a considerable improvement on the old process, and made the ore from Martha profitable (Martha mine purchased in 1890). Mr TH Russell was in charge of operations, and was determined to make the mill successful.

However, the new Waihi Mill was not without its detractors, the writers in the 1889 Mines Report having this to say: The whole of the machinery is fitted up in a good workmanlike manner, but the arrangement of the plant does not do credit to the superintendent: there is by far too much power lost in lifting and elevating the material from one process to the other, and that power will be expensive, especially where steam is used, on account of the cost of fuel. The plant, no doubt, should have been placed in such a position that the ore could be run directly to the rock-breaker, and from thence by gravitation to every other process that it has to go through, so as to economize labour and motive-power. The Globe mills erected here are new machines in the colonies; but it is very questionable if they will prove economical crushers, judging from the one working at the Melbourne Exhibition. They require a large amount of power to drive them, and the wear-and-tear on the balls and casing must be very great. The Waihi Company's plant has, however, many good points about it, and will certainly save a larger percentage of the bullion than was formerly done. It has cost about £12,000.

This company have done a great deal of work; but through being in too great a hurry, I am sorry to say, put their plant up in the wrong place. They had intended to use steam only, but now have decided to bring in water, which will cost fully £2,000; but, unfortunately, through the plant being where it is, the loss in the fall will be very considerable and the power greatly reduced; but even with these drawbacks the water-power will reduce the expenses and help to insure its being a success. If this process can do what Mr. Russell claims for it, the plant they are erecting will be sufficient for the whole of the Waihi District.

Even the directors of the company had this to say in their report to shareholders for the 1888 year:

There have been mistakes made in connection with the Mill, involving loss of time and waste of money. Some of these failures were, no doubt, incidental to starting a process, new to New Zealand, for the special treatment of our ore. The Directors can see no good result from apportioning blame for these mistakes. The necessary steps have already been taken to rectify them.

At the outset of the Company's operations the cost of timber and other materials required, the cost of transport over long distances and difficult roads, and the cost of construction of the buildings, works and roads were all very much under-estimated, moreover as the plan of operations was developed, the actual requirements became much more extensive than was at first realised, and it soon became apparent that sufficient working capital had not been provided.

Shareholders will remember that the original plan was to drive the machinery of the mill by water power; it was not carried out at the commencement for want of funds, and because the estimated cost was greater than it was afterwards found to be, and the Directors were advised that steam power would more cheaply and speedily procure funds from the mine with which to construct the water-race. The original plan has now been resorted to. Contracts have been made for constructing the water-race so as to drive the whole plant by water power.

The establishment of a smoothly operating mill was not achieved without many set backs and considerable frustration. The Globe mills were a failure, and were replaced by 30 head of stamps. Globe mills crushed dry, so they were probably a logical choice (and probably cheaper). Unfortunately they were not up to the task. Stamps traditionally crushed wet, and so I suspect were not the first choice for that reason. This was all new ground for the company, as they were the first in New Zealand to attempt dry crushing on this scale.

Experimentation continued.

The Waihi Mill, from the Auckland Weekly News, May 1912.
The Waihi Mill, from the Auckland Weekly News, May 1912. Looking over the Mill to Baker and Clarke Streets.

1890 Mines Statement: The operations at this company's works have consisted in nothing but experimenting as to the best class of machinery to adopt. For the past twelve months machinery has been erected and pulled to pieces again and again, and another class of machinery tried. Explosives have even been used to break up some of the original plant, without any other apparent reason than to prevent its remaining a memento of the experiments. There is, however, a good plant now erected, and it is to be hoped that there will be an abundance of payable ore to refund the shareholders for the large outlay and money spent in foolish blundering, which would not have been tolerated had it belonged to local proprietors; but, unfortunately, the money spent is foreign capital, and unless the mine possesses some rich ore to recoup the outlay it will be the means of retarding the introduction of capital into the colony for mining ventures.

Oh dear. There’s more.

1891 Mines Statement: The manager, Mr. H. Russell, deserves credit for the energy and perseverance he has displayed in combating the many obstacles he had to contend with in the erection of this plant from first to last; indeed, the expenditure made on works and plant by this company is stated to be somewhere about £60,000, and it seemed at one time as though the venture would not prove remunerative enough to pay interest on the large outlay, as the quantity of ore in the properties originally purchased from the Union and Rosemont Companies was not sufficient to recoup the outlay.

So, a very expensive mill, and not a lot of ore to pay for it. Time for TH Russell to buy the Martha property, and sell it on to the Waihi Company. Plenty of ore then!

1893 Mines Statement: After the Waihi Company had erected a very expensive crushing-plant to treat the ore from the Union and Rosamond Mines, which at that time were the only mining properties belonging to the company, Mr. T. H. Russell, who was superintending the crushing operations, saw that these mines were not capable of supplying a sufficient quantity of ore to keep the plant fully employed: and, indeed, the large expenditure on this plant, with the continued alterations from time to time, would have placed the company in liquidation had they not got a better mining property. However, Mr. Russell, in casually examining the Martha Mine, and getting different parcels of the ore, taken promiscuously, analysed, found that the ore was very rich in both silver and gold, and, instead of the ore containing only 4dwt. and 6dwt. to the ton, some of it was worth nearly £100 per ton. He consequently made the Martha Company what they considered an excellent offer for their property, which was accepted, and this property at the present time is one of the best in the colony.

Experiments in wet crushing did not persuade the Company to abandon dry crushing.

The Waihi Company was rather slow to take up the cyanide process; the Silverton mill converting before them (the royalties payable to the Cassel Company were something of a stumbling block). They trialed briefly the Bohm process, but in 1893 sold their saved tailings to the Cassel Company and established a trial cyanide plant of their own. This proved so successful; they abandoned the pan amalgamation process completely in favour of the cyanide process in 1894.

Doing away with pan amalgamation freed up considerable power reserves which could power more stamps. Thirty were added the same year (1894).

An Otis ball mill was trialed, but discarded. Krom rolls likewise.

The Company was slow also to give up dry crushing, doing so in 1902, five or six years after the Crown Battery in Karangahake had done so.

Continued experimentation and development saw 26 Union vanners installed in 1903, tube mills added to the plant in 1904, and air-agitation tanks, to effectively treat slimes, were constructed in 1909-10.