Medium-scale mining

Medium-scale mining refers to mining that is larger than artisanal or small-scale mining but smaller than large-scale mining. Its exact definition may vary by country and also between different organizations within a country. Some criteria are based on the yearly man-hours employed in the mining operation and others on either the total mass ore extracted, the mass of metal (or non-metallic mineral) extracted or the dry-equivalent mass of ore concentrate produced.

The Chilean mining guild Sociedad Nacional de Minería (SONAMI) defines medium-scale mining as those producing copper in the range of 1,500 to 50,000 metric tons per year.¹ For the mining of other metals and non-metallic mining SONAMI's definition of medium-scale mining is based on equivalents on the tonnage that defines medium-scale copper mining.¹ For Chile's National Geology and Mining Service medium-scale mining is that which employ between 1 million and 200 thousand man-hours per year, which is equivalent to a full-time workforce of between 80 and 400 persons.² For Chilean state-owned company Empresa Nacional de Minería (ENAMI) medium-scale mining is different from the small scale mining in that it has a monthly produce of exceeding one of the following; 300 metric tons of dry copper concentrate, 150 metric tons of dry gold-silver concentrate, 100 metric tons of dry copper precipitate or else a total produce of 10,000 metric tons of mineral.² The Chilean Copper Commission uses a definition offered by the Instituto de Ingenieros de Minas de Chile in 1990 which considers medium-scale mining as those mining companies producing between 3,000,000 and 100,000 metric tons of copper yearly (8,000 to 300 dayly).³ In Peru the law Ley General de Minería defines medium-scale mining as that which has a dayly produce of in the range from 350 to 5,000 metric tons ore concentrate or more processesed ore.⁴

In Chile medium-scale mining (Spanish: mediana minería) is concentrated near roads or other pre-existing infrastructure, and lie thus away from the high Andes where nearly all mines belong to the large-scale mining category.⁶⁵ For mines with an annual produce of less than 10,000 metric tons a simplified mine closure procedure apply in Chile.⁷ ENAMI has in its role the purchase of ore from medium and small-scale mining which it does at stabilized prices to avoid volatility.⁸⁹ There are multiple policies in Chile that tend to group media and small-scale mining together.¹⁰ Medium-scale mining in Chile tend to focus on copper and produced about 4.5% of the copper mined in the country from 2017 to 2021,¹¹ with Chile being the world's largest producer of copper.¹²¹³

Medium-scale mining in Chile has a high rate of success in the environmental impact assessments with an approval rate of 92% from 2017 to 2022.¹⁴ Yet these approvals last each for a few years as projects submitted by medium-scale mining involve short time-frames.¹⁵ A 2017 study show that medium-scale mining in Chile is 23% less efficient in its use of water relative to large-scale mining, yet it has been suggested to be in favourable conditions to apply environmental techniques such as dry tailings relative to large-scale mining.¹⁶