The Toyo Smelter & Refinery is located in both Saijo City and Niihama City, Ehime Prefecture. The Toyo plant is a large-scale seaside copper smelter. It has established the world's top-class technologies for smelting, production control, and environmental preservation.
To date we have made capital investments into copper mines in South America, Australia and Southeast Asia in a quest to secure stable supplies of the raw materials needed for our copper smelting operations. The mined ore is dressed on-site to enhance its purity, and the resulting “concentrate” is then shipped to Japan. Copper concentrate contains about 30% iron and the same percentage of sulfur content, but it also contains a small amount of precious metals, such as gold and silver, all of which are collected. In addition, in the Toyo plant, we use gold ore yielded from our Hishikari Mine (Kagoshima Prefecture) as solvent (silica) for refining copper.
Copper : approx.30%
Iron : approx.30%
Sulfur : approx.30%
Gold : 40 to 45 g/t
Copper concentrate to be smelted is carried in by a special carrier and then unloaded from its special berth. Up to 30,000 ton class carriers can dock in the berth.
Since copper concentrate contains about 8% water, it is dehydrated using a dryer. For dehydrating concentrete, not only dryers that use heavy oil but also steam dryers that use the heat of steam collected in the plant are used, which helps save energy.
In order to make crude copper of 98% purity from copper concentrates, copper is concentrated in a flash furnace first. Copper concentrate and gold ore are put in the flash furnace, and hot wind is blown in for them to be oxidized and melted. Because sulfur content in the copper concentrate works as fuel to maintain high temperature, the furnace is called flash furnace. Copper that has been concentrated so that its grade is 60 to 65% is called matte. Dependant on the difference in specific gravity, slag (its main components are iron oxide and silicic acid) is separated from matte.
Matte with a copper grade of 60 to 65% is sent from the flash furnace to the converter in order to increase its purity. With oxygen blown into the converter, the sulfur content is removed as a gas and iron is removed into silicon (main component of gold ore). As a result, a portion of the matte becomes slag. Thus, crude copper with purity of 98% is taken out from the converter to a refining furnace, where oxygen concentration is adjusted.
The gas generated while copper is refined (SO2) is collected and changed into sulfuric acid in the sulfuric acid facility.
The copper output from the refining furnace is cast into a mold, forming a refined anode.
One anode weighs about 400 kilograms.
Electrolytic copper with a purity of 99.99% are produced by electrolytic methods. Precious metals or rare metals contained in the anodes remains as anode slime (deposit) at the bottom of the electrolytic tank and is then sent to the precious metal refining plant.
The Gold ingot is cast, and the mark, number, and purity are impressed onto it.
Particles of gold 2-3 mm in diameter are manufactured.
The refining anodes taken out from the refining furnace is changed into electrolytic copper with purity of 99.99% through an electrolysis process.
Slag Sand （water-granulated slag） is produced by placing the solution part of slag into running water. Since extraction of sea sand has been progressively banned due to consideration of the environment, Slag Sand is drawing attention as a substitute for concrete fine aggregate material.
Slag powers are made by refining the electrolytic solution in the copper electrolysis tank. Slag powder is mainly used for the copper plating of printed circuit boards.
Various sizes of gold ingots are manufactured.
Features : easily soluble.
Features : easily soluble, similar to the corresponding gold product.