Hatti Gold Mines

HGML

Hutti Gold Mines Company Limited (HGML), Government of Karnataka Undertaking (Established in 1947 as Hyderabad Gold Mines), has the unique distinction of being the only producer of primary gold in the country. HGML has been active in the exploration, development and exploitation of gold deposits occurring in Karnataka. The Company's Corporate Office is situated in Bangalore and it operates two units-The Hutti Gold unit (HGU) ,in Raichur district and the Chitradurga Gold Unit (CGU) in Chitradurga district with an operating mine at Ajjanahalli (Tumkur District) .HGU is a fully integrated unit with a capacity to produce 5,50,000 tonnes per annum.

History

This mine is probably one of the most ancient metal mines in the world, dating to the Pre-Ashokan period, the ancient miners having worked down to a depth of over 2300 feet. It is probable they had broken the rock by "fire-setting" i.e. heating it by means of fires and suddenly cooling it by pouring water onto the heated rock causing pieces to break off. As per carbon dating done by Dr. Rafter from Australia in the year 1955, the age of the two samples of timber found in old workings was estimated to be about 1980 years old.

In addition to the ancient mining mentioned above, there was further mining in the area between 1890 and 1920 when the price of gold was about Rs. 18 for 10 grams (Rs 20.97 per tola). The biggest of these ventures was at Hutti where, from 1902 to 1919, nearly 7,400 kg of gold were obtained from very rich ore, at an average yield of 19 g/metric tonne. Most of this ore came from the main mine, which reached a depth of about 1,100 m below surface. The industry closed down in 1920 due to technical difficulties and lack of funds.

In 1937, the Nizam's Government decided to prospect the area again with a view to possible re-opening of the mines (the only industry in the area apart from agriculture) so as to provide employment. The area was a backward district, which was considered at that time to be a more or less perpetual famine area. In 1940, after some satisfactory exploratory work, it was decided to install a plant to treat 100 metric tons of mine ore per day, but before the plant could be obtained, operations were suspended, and from 1942 to 1946, due to World War II, the mine was shut down except for pumping. After the end of the war, the scheme was resumed and production started in September 1948, at the rate of 130 tonnes of ore per day. By 1972 this rate had progressively increased to 600 tonnes of ore per day.

Ancient mining techniques

The ancient miners worked down to depths between 35 and 190 metres. According to archaeologists, the fire-setting technique was used in the ancient period to break down rocks in the mine, by alternating between heating and cooling. Grinding stones then crushed the ore to extract gold. A mixture of crushed ore and water was passed through goat’s skin to separate heavy gold particles from lighter impurities.

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