eMalahleni , South Africa ( CNN ) -- A South African coal-mining company is cleaning up its act by building cheap , eco-friendly housing using its industrial waste . For some years AngloAmerican -- one of the world 's largest mining firms -- has been purifying the water contaminated during its coal mining activities in the South African city of eMalahleni . Now , AngloAmerican is mixing the waste by-product -- a mineral known as gypsum -- with cement to make energy-efficient bricks it uses to build houses there . `` We 've built 62 houses so far , '' said Peter Gunther , AngloAmerican 's head of sustainable development , and the driving force behind the initiative . `` Each home requires about eight tons of gypsum , but at present we 're removing over 200 tons of it from the water every day . '' Gypsum is a basic mineral compound of calcium and sulphur . The non-toxic mineral is soluble in water , but becomes harder and more adhesive the hotter and dryer it gets . Because gypsum is malleable when wet , its most common commercial application to date is as the main ingredient for household plaster . `` Actually , there are 50 different uses for it -- from dental surgery to fireproofing doors , '' said Gunther . `` But there is a serious housing shortfall here , and we have so much gypsum , that once we decided we needed to do something with it , making a strong building material was the obvious choice . '' And Gunther believes that his new bricks have significant advantages over the heavy cement ones typically used in the area : `` The bricks are generally harder than traditional cement bricks , they 're also better heat and sound insulators , '' he said . But , most crucially for one of the fastest growing urban areas in South Africa , the gypsum bricks have a lower environmental impact . `` Because it ( gypsum ) is such a strong binding agent , we need much less cement to make ( the bricks ) , '' said Gunther . According to figures from the Cement Sustainability Initiative , about 5 % of all the world 's man-made CO2 emissions stem from the chemical and combustion processes involved in cement production . Most types of cement are made by heating limestone , a chemical process known as calcination which releases large amounts of carbon dioxide into the atmosphere . The industrial manufacture of cement also requires large quantities of fuel . Gunther claims that his low-cement bricks save , on average , three tonnes of carbon dioxide for every home built . Read related : 'Living ' buildings could inhale city carbon emissions . In the city of eMalahleni -- a name that in Zulu literally means `` place of coal '' -- AngloAmerican aims to provide new homes for its entire local workforce , with 400 scheduled to be built in the next year . `` This is my first house ... this is my dream house , and I 'm happy . It 's not small . I feel free with my family , '' enthused Maria Mhlongo , whose husband works at one of AngloAmerican 's coal mines in eMalahleni . The Mhlongo family was among the first to move into a gypsum-brick house after the company started building accommodation for its workers in 2010 . But can gypsum -- a product that AngloAmerican had been discarding as waste before last year -- really be such a wonder material ? Andrew Bloodworth is head of minerals at the British Geological Survey . He says that gypsum , `` a relatively common mineral geologically , '' is indeed a great heat insulator and can be very strong -- but only as long as it stays dry . `` I 've never heard of it being used to make bricks because it 's water soluble -- that 's why it 's so good as a plaster agent , '' said Bloodworth . `` I 'd be interested to know how they 've managed to get around that . '' Gunther says that because the bricks are still partially composed of cement , they are fully water resistant . `` The brick mixture has been subjected to the most rigorous trials by the South African Bureau of Standards , and passed without any problems , '' he added . Global carbon emissions from coal are second only to oil , according to the UN Environment Program , while other environmental factors such as air-pollution from coal dust and damage caused by mining also remain a serious problem . Gunther acknowledges these issues , but says that coexistence between energy sources is necessary `` for as long as the world is so much set up around running on coal . `` While we 're still using it , the question is : What can we do to make it cleaner and even more useful ? I think our approach goes some way to achieving that goal . ''
Mining firm claims to produce sustainable building materials from waste . Mineral gypsum extracted from polluted water ; mixed with cement to make bricks . Over 60 houses built so far , each one saving estimated three tons of CO2 , says firm .