The Waihi Gold Mining Company established the Victoria Battery in 1897/98.
Waihi ore (and Hauraki ore in general) was difficult ore to process. Refractory, with gold finely divided and often intimately bound to sulphide minerals. Ore roasting and dry crushing followed by cyanidation had been established as best practice at the Waihi Battery, and thus this was the process set up at the new Victoria Battery. Huge ore roasting kilns were built, with vast quantities of firewood required. Miners and battery hands were maimed by “the dust” (phthisis or silicosis).
100 stamps started dry crushing on March 2nd, 1898.
The ore was crushed to fine sand and transported to leaching vats by pipe conveyor. Cyanide solution was percolated through the sands; there was no agitation. Percolation was only successful if there was very little fine material (called slimes) in the sands. Roasting and dry crushing mostly achieved this.
Experiments in wet crushing, over many years, were on going. The increasingly mineralised ore found at depth in Martha mine added to the pressure to convert.
In May 1899 a start was made to erect a further 100 stamps which were to be wet crushing.
By mid January 1900 the 100 wet stampers were fully operational . The original 100 dry stampers were converted during 1902 .
The change to wet crushing, and the more mineralised nature of the ore required changes to the battery flow sheet.
Wet crushing, without preliminary ore roasting, produced more very fine material (slimes). Slimes prevented the percolation of cyanide solution through the crushed ore (called pulp). The slimes had to be separated and treated by agitation. The highly mineralised portion of the ore proved resistant to the regular process, so was also removed, and treated separately.
The three products were separated from the stamper output and treated individually; sands, concentrates, and slimes. The battery buildings, machinery and processes reflected this. Alterations and refinements were made over time. The difficulty of agitating slimes was largely overcome by air agitation in tall tanks.
After electrification in 1913/14, the structures of the battery site remained relatively unchanged until their demolition after closure in 1952-4. The concrete and stone foundations of these structures are what remain today, modified or obscured by scavenging activities before the Department of Conservation acquired the site in 1987. The Department and the Victoria Battery Tramway Society have further modified the site over the years.
These details are explored in a research document. The available contemporary photographs are assembled, discussed, and arranged by year.
The Victoria Battery GIS is an integral part of this project. The research and interpretation here presented have informed the expansion and updating of the GIS.
The document is available here (210 pages, 19 mb PDF).
Victoria Battery Concentrates Tailings Stack
The highly mineralised component of the ore, rich in gold and silver, needed to be extracted from the general crushed ore and treated separately. This is called concentration, and produced concentrates. A Concentrates Treatment Plant (CPT) was established, first an experimental plant in 1901, and a permanent plant in 1905, treating the concentrates from all three batteries (Victoria, Waihi, and Union). The tailings (waste) of the CTP were initially saved for possible future reprocessing. They were at first stacked beside the CTP, but in 1906 these were moved to the site beside the tramway, some 500m from the battery. How the tailings were transported is unknown.
This site became full in late 1907; no further tailings were added, or saved elsewhere.
Superintendent H. P. Barry felt that “We have very little hope of ever being able to treat these tailings at a profit” .
However, there is some evidence to suggest that some of these tailings were reprocessed; at the end of the Waihi miners’ strike of 1912, when the ore supply from Martha mine was still low, and also in the early 1940s, as ore production from the mine dwindled.
The document is available here (50 pages, 6.3 mb PDF).