Hutti Gold Mines Limited

Hutti Gold Mines Limited (Kannada: ಹಟ್ಟಿ ಚಿನ್ನದ ಗಣಿ) (HGML) is a company located in the state of Karnataka, India and engaged in the mining and production of gold. This was first established as Hyderabad Gold Mines in 1947. With the closing of Kolar Gold Fields in 2001, this is the only company in India which produces gold by mining and processing the gold ore. Owned by the Government of Karnataka, HGML has two plants located in Hutti and Chitradurga. HGML mines gold from its main gold mine located in Hutti and other satellite mines.

The Company's Corporate Office is located in Bengaluru.

The mines managed by HGML are mainly located in the Hutti-Muski precambrian greenstone belt which contains both readily extractable native gold and gold-bearing sulphides. HGML consists of two gold units:

These mines in total produce about 3 tonnes of gold a year. With the closure of the Bharat Gold Mines Limited which had operations at Kolar Gold Fields in Karnataka and at Chittoor district in Andhra Pradesh, HGML is the only company in India that produces gold by mining. It has gold ore reserves of about 31.02 million tonnes which could last for about 60 years and yield about 150.4 tonnes of gold.

The process of cyanide leaching is used by HGML to extract native gold which is present in a quartzite matrix. However, this method cannot be used to extract gold which is present in sulphides. HGML has made use of advanced technologies like biotechnology to come up with a cheaper and efficient method to extract gold from sulphides. With the help of the Indian Institute of Science, Bangalore, an extraction method was devised in which the sulphides were subjected to oxidation using the bacteria, Thiobacillus ferrooxidans under optimal conditions. The bacteria dissolved the sulphides like pyrite and arsenopyrite and thus revealed the native gold. The native gold was then subjected to cyanide leaching to produce pure gold. This method also produces other precious metals like silver which could be present in the sulphides. After repeated experimentations to come up with the optimal procedure, HGML constructed the first bioreactor in the middle of 2001.

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