Sulphide copper, CuS, with its characteristic blue-black color and hexagonal or monoclinic crystal structure, boasts a metallic luster. Found naturally in the form of chalcopyrite (indigo copper ore), it exhibits a density of 4.6 and stability in dry air. However, exposure to moisture prompts oxidation into copper(II) sulfate, and upon heating to 220°C, it undergoes decomposition.
This fascinating compound is sparingly soluble in water and ethyl alcohol, with a very low solubility product (8.0×10^-37). It finds its way into chemistry through its selective solubility in hot dilute nitric acid, concentrated hydrochloric acid, or sulfuric acid, forming corresponding copper(II) salts. It readily dissolves in solutions of potassium cyanide (KCN) or calcium cyanide (CaCN), giving rise to the tetra-cyanocuprate(II) ion, [Cu(CN)4]3-.
In industrial applications, sulfuric copper's insolubility is巧妙地 utilized to separate metal ions in solutions. For instance, in a mixture of Ni2+ and Cu2+ or Zn2+ ions, adjusting the pH slightly acidic and introducing hydrogen sulfide gas leads to the formation of black CuS precipitate, effectively removing Cu2+ for purification purposes. Lab experiments often involve converting sulfuric copper by bubbling H2S into a weakly acidic solution or adding ammonium sulfide to obtain the purified compound.
But the story doesn't end there; sulphide copper's industrial prowess extends to copper smelting. The modern method, known as flash smelting, employs fine sulfuric copper ore in high-temperature, oxygen-rich air currents. This process, initiated in the late 19th century, has rapidly evolved into an energy-efficient and pollution-reducing technique for refining copper. Companies like Outokumpu and Inco Ltd have spearheaded this advancement with their respective technologies.
The flash smelting furnaces have transformed the way we extract copper from硫化矿, with over 30 operational facilities worldwide, accounting for a significant portion of global copper production. As a result, this method has emerged as a vital strategy in the metallurgical landscape.