History:

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.

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 you tube on three languages: English, Spanish, French and Indonesian.

Google: gold borax for English version (https://www.youtube.com/watch?v=X6Sawj0HyF0),

Google: oro boraks for Spanish version (https://www.youtube.com/watch?v=-3uiKeCBkjk)

Google: emas boraks for Indonesian version (https://www.youtube.com/watch?v=ERjH-SKsFNo).

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

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

The crushed gold ore is let into a tub where first separation 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 minerals being leet onto the chute.

Milled material is let to a tub

Milled material is let to a tub

Tub

Tub

Chute were heavy minerals and gold is captured

Chute were heavy minerals and gold is captured

 

 

Panning

Panning

The mercury-free method has been taught in several countries and most places people are skeptical in the beginning. However, when we make a competition where we let the miners process a number of sacs of gold ore their way and then we process the same number of sacs mercury-free and measure the amount of god recovered the mercury-free method aways winn. Below is a table of such tests in different countries.

table01
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.