A Study on Reduction of Copper Smelting Slag by Carbon for Recycling into Metal Values and Cement Raw Material

Abstract

Copper smelting slag is a solution of molten oxides created during the copper smelting and refining process, and about 1.5 million tons of copper slag is generated annually in Korea. Oxides in copper smelting slag include ferrous (FeO), ferric oxide (Fe­2O3), silica (SiO­2 from flux), alumina (AI2O3), calcia (CaO) and magnesia (MgO). Main oxides in copper slag, which iron oxide and silica, exist in the form of fayalite (2FeO·SiO2). Since the copper smelting slag contains high content of iron, and copper and zinc. Common applications of copper smelting slag are the value added products such as abrasive tools, roofing granules, road-base construction, railroad ballast, fine aggregate in concrete, etc., as well as the some studies have attempted to recover metal values from copper slag. This research was intended to recovery Fe-Cu alloy, raw material of zinc and produce reformed slag like a blast furnace slag for blast furnace slag cement from copper slag. As a results, it was confirmed that reduction smelting by carbon at temperatures above 1400°С is possible to recover pig iron containing copper from copper smelting slag, and CaO additives in the reduction smelting assist to reduce iron oxide in the fayalite and change the chemical and mineralogical composition of the slag. Copper oxide in the slag can be easily reduced and dissolved in the molten pig iron, and zinc oxide is also reduced to a volatile zinc, which is removed from the furnace as the fumes, by carbon during reduction process. When CaO addition is above 5wt.%, acid slag has been completely transformed to calcium silicate slag and observed like blast furnace slag.

Case Study of Municipal Waste and Its Reliance on Reverse Logistics in European Countries

“…In the beginning, consumers buy the product they need, such as a newspaper or a soft drink. After reading a newspaper or drinking a soft drink, the product usually runs out, or the newspaper read becomes irrelevant, the product's useful life ends [130]. And then, consumers have to decide how to dispose of waste properly.…”

Gold recovery from flotation concentrate from gold mine tailings using dissolve smelting

“…Consequently, the gold can be separated from pure copper during electrolytic refining. It is thus possible that the regenerated concentrate slag can be completely recycled for iron recovery and value added products such as abrasive blasting, roofing granules, concrete, and other materials [9][10][11][12]. The sulphides in the flotation concentrate are fully converted to an oxide form during oxidative roasting, hence the chemical composition of the roasted concentrate can be considered as a copper slag.…”

“…The sulphides in the flotation concentrate are fully converted to an oxide form during oxidative roasting, hence the chemical composition of the roasted concentrate can be considered as a copper slag. Recovery of pig iron containing copper from copper smelting slag by reduction smelting was also recently examined, and successfully performed, and produced the pig iron [9][10][11].…”

The Use of Coffee Waste in the Reduction of Metallurgical Slags

“…The concept of using SCG waste in the slag reduction process results from the decline in coal extraction observed in recent years in EU countries, and thus the reduction in the production of coke and coke breeze. The two carbon-bearing materials, as well as graphite and anthracite, are the basic carbon-bearing materials used in pyrometallurgical processes of copper recovery from slags [13][14][15][16]. It should be mentioned that there are also studies on the use of fine-grained coal fractions in these processes, generated in coal enrichment or processing [16][17][18], as well as waste oils and biomass [19][20][21][22][23][24][25].…”

“…The two carbon-bearing materials, as well as graphite and anthracite, are the basic carbon-bearing materials used in pyrometallurgical processes of copper recovery from slags [13][14][15][16]. It should be mentioned that there are also studies on the use of fine-grained coal fractions in these processes, generated in coal enrichment or processing [16][17][18], as well as waste oils and biomass [19][20][21][22][23][24][25].…”