History

Milled material is let to a tub

Milled material is let to a tub

 

About thirty years ago a small-scale gold miner in Benguet province of Philippines found an alternative to gold extraction using mercury. He had probably watched a chemist at a commercial gold mine testing gold ore by smelting crushed and milled ore with borax whereby a small pellet of gold was produced. He tested the method at home and found that it not only saved him buying mercury, but he recovered more gold without working harder. The method spread fast in his local area and for thirty years about 25,000 small-scale gold miners have extracted gold mercury-free.

 

Tub

Tub

The method is simple and does not require investment in expensive equipment. It is mercury-free and thus the miners are not exposed to pollution by metals heavy. As a bonus it mostly recovers more gold than amalgamation methods without being more time consuming. An educational video has been produced and can be seen on youtube on four languages: English, Spanish, French and Indonesian.

The educational video was made by Peter Appel, Geological Survey of Denmark and Greenland in cooperation with Heinemann Media, Denmark and Leoncio D. Na-Oy Emerald Small Scale Multi-Purpose Cooperative, Philippines.

Chute were heavy minerals and gold is captured

Chute were heavy minerals and gold is captured

 

 

 

 

 

Panning

Panning

The method has been named borax method, but a more appropriate name is Philippine mercury-free gold extraction, since borax is only used in the final step of the processing.

The milled gold ore is let into a tub where first seperation of very fine grained gold is released to the chute where a layer of cloth captures the fine gold. Next step is the coarser heavy minirals including gold being let onto the chute.

 

 

 

The mercury-free method has been taught in several countries and most places people are skeptical in the beginning. In order to convince the miners we make a direct comparison of the two methods.

We take a number of sacs of ore and mill the ore. Then the ore is carefully split into two equally big heaps. The local miners process their heap using mercury. We process the other half without using mercury. We measure time spent and amount of gold recovered. The mercury-free method takes up to 10 percent longer time, but recover up to 70 percent more gold.

This demonstration has successfully been carried out in several countries.
Mercury-free gold extraction versus whole ore amalgamation/simple amalgamation
In all tests shown in the table time duration using the two different methods were measured. Time consumption of the two methods is virtually the same with a small tendency that mercury-free gold extraction is slightly faster. In Gaang 1800 miners have worked mercury free for three years.