Backyard furnaces were small steel blast furnaces used by the people of China during the Great Leap Forward (1958–62). These were constructed in the backyards of the communes, and were done so to further fulfill the Great Leap Forward's ideology of the rapid industrialization of China.
People used every type of fuel they could to power these furnaces, from coal to the wood of coffins. Where iron ore was unavailable, they melted any steel objects they could get their hands on, including utensils, household objects like chairs and doors, bicycles and even their own farming equipment, all of which was to produce steel girders. However, most of the steel was impure and of poor quality and thus cracked easily. Unbeknownst to the Communist Party officials, the result was not steel, but high carbon pig iron, which needs to be decarburized to make steel. It was not until 1959 did the Party realize that the only steel of any worth being produced was in the large-smelting plants, with results within the communes being practically obsolete. Even worse, the tending to Backyard Furnaces in the communes denied peasants the time and opportunity to produce food, effectively starving many and directly contributing to the Great Chinese Famine that struck the country only a year later.
The results varied from region to region. In regions where the steelmaking tradition had survived unbroken, where the old skills of the ironmasters had not been forgotten, the pig iron was indeed further refined into steel, and the steel production actually did increase. In regions that had no traditions of steelmaking, or the old ironmasters had been killed, or if there was no theoretical understanding of the blast furnace process and refining of the pig iron, the results were unsatisfactory. At worst, the fuel used was high-sulfur coal, rendering even the resulting pig iron useless and needing to be re-smelted and desulfurized.