Since since patent of cyaniding dissolve gold came out 1887 , people explores the avirulent technology that extract gold ceaselessly .
自从1887年氰化溶金专利问世以来,人们不断探索无毒提金工艺.
Method : jimo municipal district all elementary and middle schools student total 4072 ; carries on based on the world health organization ( who ) recommendation cyaniding high-valence iron law picks the blood and the diagnosis .