The present invention relates to a method of separating rare earth elements from rare earth polishing powder waste by a hydrometallurgical process, the method comprising the steps of: synthesizing sodium rare-earth double sulfates by adding sulfuric acid and sodium hydroxide to the rare earth polishing powder waste; converting the sodium rare-earth double sulfates into rare earth hydroxides; and separating cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) from the rare earth hydroxides by adding hydrochloric acid and sulfuric acid. The present invention makes it possible to recover 99% or more of rare earth elements, including cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) from rare earth polishing powder waste, and enables the recovered rare earth elements to be recycled, thereby achieving great industrial economic benefits.

The present invention relates to a method of separating rare earth elements from rare earth polishing powder waste by a hydrometallurgical process, the method comprising the steps of: synthesizing sodium rare-earth double sulfates by adding sulfuric acid and sodium hydroxide to the rare earth polishing powder waste; converting the sodium rare-earth double sulfates into rare earth hydroxides; and separating cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) from the rare earth hydroxides by adding hydrochloric acid and sulfuric acid. The present invention makes it possible to recover 99% or more of rare earth elements, including cerium (Ce), lanthanum (La), praseodymium (Pr), and neodymium (Nd) from rare earth polishing powder waste, and enables the recovered rare earth elements to be recycled, thereby achieving great industrial economic benefits.

Disclosed herein are system and methods to effectively leach coal ash with hydrochloric acid and separate an insoluble silica product and then selectively precipitate, from the leachate, a number to value-added, strategic, marketable products using a hydroxide reagent. The resulting precipitated products include iron, aluminum, magnesium, calcium, and a mixture of rare earth elements and transition metals. These can be separated as hydroxides or converted to oxides or carbonates. Using hydrochloric acid for leaching and converting the chloride to sodium chloride in the final step results in practically no waste for this process. The silica can be further purified using sodium hydroxide fusion or caustic leach methods and some minor streams from this process are recycled to minimize any waste stream. These systems and methods can be applied to a number of other industrial waste products such as red mud from the aluminum process, slag from steel furnaces, mine tailings, and other metal-bearing waste streams.

Disclosed herein are system and methods to effectively leach coal ash with hydrochloric acid and separate an insoluble silica product and then selectively precipitate, from the leachate, a number to value-added, strategic, marketable products using a hydroxide reagent. The resulting precipitated products include iron, aluminum, magnesium, calcium, and a mixture of rare earth elements and transition metals. These can be separated as hydroxides or converted to oxides or carbonates. Using hydrochloric acid for leaching and converting the chloride to sodium chloride in the final step results in practically no waste for this process. The silica can be further purified using sodium hydroxide fusion or caustic leach methods and some minor streams from this process are recycled to minimize any waste stream. These systems and methods can be applied to a number of other industrial waste products such as red mud from the aluminum process, slag from steel furnaces, mine tailings, and other metal-bearing waste streams.

Provided is a method for separating copper from nickel and cobalt, which is capable of efficiently and selectively separating copper, and nickel and cobalt from an alloy containing copper, nickel and cobalt such as a highly anticorrosive alloy that is obtained by subjecting a waste lithium ion battery to a dry treatment and contains copper, nickel and cobalt. According to the present invention, an alloy containing copper, nickel and cobalt is brought into contact with an acid in the coexistence of a sulfurization agent, thereby obtaining a solid that contains copper and a leachate that contains nickel and cobalt.

Provided is a method for separating copper from nickel and cobalt, which is capable of efficiently and selectively separating copper, and nickel and cobalt from an alloy containing copper, nickel and cobalt such as a highly anticorrosive alloy that is obtained by subjecting a waste lithium ion battery to a dry treatment and contains copper, nickel and cobalt. According to the present invention, an alloy containing copper, nickel and cobalt is brought into contact with an acid in the coexistence of a sulfurization agent, thereby obtaining a solid that contains copper and a leachate that contains nickel and cobalt.

Provided is a process for recovery of gold from gold-bearing raw materials comprising (a) leaching said gold-bearing raw material in a chloride containing leaching solution containing a total concentration of less than 120 g/L of halide ions, whereby the total concentration of chloride ions is less than 120 g/L of to dissolve gold and to obtain a leach solution comprising gold in solution; and simultaneously contacting the leach solution comprising gold in solution with a re-sorptive material to obtain a leach solution comprising gold-bearing re-sorptive material; and (b) recovering gold and optionally silver from the said gold-bearing re-sorptive material.

Provided is a process for recovery of gold from gold-bearing raw materials comprising (a) leaching said gold-bearing raw material in a chloride containing leaching solution containing a total concentration of less than 120 g/L of halide ions, whereby the total concentration of chloride ions is less than 120 g/L of to dissolve gold and to obtain a leach solution comprising gold in solution; and simultaneously contacting the leach solution comprising gold in solution with a re-sorptive material to obtain a leach solution comprising gold-bearing re-sorptive material; and (b) recovering gold and optionally silver from the said gold-bearing re-sorptive material.

A method of extraction of pure iron (III) oxide from bulk iron ore is provided that includes crushing and grinding, using a crushing machine, raw hematite ore, where a milled ore is formed, water-washing the milled ore by rinsing under continuous stirring conditions, dilute acid-washing the milled ore with diluted hydrochloric acid under continuous stirring conditions, immersing the dilute acid-washed milled ore in concentrated acid under the continuous stirring conditions, and applying heat, treating the heated and immersed milled ore with an alkali to form a precipitate, washing with water the precipitate to purify the precipitate, and drying the purified precipitate, and igniting the purified dry precipitate to extract a pure iron (III) oxide from a bulk iron ore.

A method of extraction of pure iron (III) oxide from bulk iron ore is provided that includes crushing and grinding, using a crushing machine, raw hematite ore, where a milled ore is formed, water-washing the milled ore by rinsing under continuous stirring conditions, dilute acid-washing the milled ore with diluted hydrochloric acid under continuous stirring conditions, immersing the dilute acid-washed milled ore in concentrated acid under the continuous stirring conditions, and applying heat, treating the heated and immersed milled ore with an alkali to form a precipitate, washing with water the precipitate to purify the precipitate, and drying the purified precipitate, and igniting the purified dry precipitate to extract a pure iron (III) oxide from a bulk iron ore.