Heavy metals is improved with the addition of thorium. Tellurium is added to copper and steel alloys to improve their machinability; and to lead to make it harder and more acid-resistant. The biocidal effects of some heavy metals have been known since antiquity. Platinum, osmium, copper, ruthenium, and other heavy metals, including arsenic, are used in anti-cancer treatments, or have shown potential. Antimony (anti-protozoal), bismuth (anti-ulcer), gold (anti-arthritic), and iron (anti-malarial) are also important in medicine. Copper, zinc, silver, gold, or mercury are used in antiseptic formulations; small amounts of some heavy metals are used to control algal growth in, for example,
Hunan Nonferrous Metals Hunan Nonferrous Metals Hunan Nonferrous Metals Holding Group Co., Ltd. is a nonferrous metals company of China. It is a subsidiary of China Minmetals, which in turn indirectly under supervision of State-owned Assets Supervision and Administration Commission. Some of the assets of the conglomerate was listed in Hong Kong Stock Exchange from 2006 to 2015 as "Hunan Nonferrous Metals Corporation Limited" (SEHK: 2626). (The holding company retained Hunan Yaogangxian Mining Co., Ltd., Hunan Huangshaping Mining Branch and a joint venture (Duddar mine).) However, in 2014 China Minmetals announced the plan to privatization of the listed company, which China Minmetals already