| Show making the charge to make the desired slag it is necea sany to mix certain fluxes usually silica iron oxide and limestone with the ore in such proportions that after the matte has been formed the remaining constituents of the charge will form an ail easily fusible and fluid slag the calculation of the aarde charge Is to the experienced superintendent a comparatively ively simple operation in chemical arithmetic it is customary to allow 90 per cent of the slag to silica iron oxide and lime the rema remaining mairin re iving 10 per cent being composed of aluminum oxide barium oxide manganese oxide and such other compounds as may be present in the crude ore the usual practice in copper smelting smelling sm elting is to make a sla slag containing 30 to 38 per cent silica the remainder of the 90 per cent being composed of lime and iron oxide and at the anaconda works which are considered as exemplifying an advanced type of copper smelting smelling sm elting it is aimed to keep the sili clous content of the slag as near to 36 per cent as possible at the yampa yarn pa however it is found that excellent results are obtained from a slag carrying in t as high as 45 to 46 per cent silica which is very desirable as it reduces the amount of limestone to be added with a consequent saving of this flux and effects a corresponding in increase in the actual amount of ore treated the process of calculating a furnace charge is briefly as follows an analysis is made in the assay laboratory of the ore for copper iron silica sulphur and lime of the coke for silica of the lime rock for pure lime of the iron ore for pure iron and the silica for its pure si licous content As it is not necessary to add the latter two to the yampa ore they may be disregarded in this example having determined by experiments guided by the most economical slag and the grade of matte that it is practical to make also the amount of sulphur which will be volatilized by the action of the furnace the determines using as a basis the same formula as for the matte how much of his iron will go toward making matte and how much will be left as slag forming material this is placed against the silica in the ore and the coke and sufficient amount of lime added to balance the excess of silica over iron lime and iron having the same effect in the blast furnace j when the furnaces were running on the yampa ore alone the fluxing flexing was a very simple matter so simple as to appear al most crude to one used to the more complex ores of a custom plant the crude ore consists of about 30 per cent each silica iron and sulphur two per cent copper and four per cent lime A train of cars is run alongside the ore and flux bins and loaded in the following proportions crude ore arounds pr lime 1400 pounds ber atory matte pounds coke pounds the fuel thus forming Eom something ething less than ten per cent of the entire charge about five to eight charges are made on the day shift with the addition of pounds of slag the slag being more fusible than the mixture in its crude state tends to keep the furnace open by preventing the formation of counters on the sides if allowed to form these counters increase in size projecting into the furnace and impeding the action of the blast until the result is a frozen furnace which must T MAP W 4 A V AV e nv room yampa smelter photo by leroy adalmer be bored out sometimes at an expense of many thousands of dollars the charges are loaded into side tipping slag cars and are dumped bodily into the furnaces through balanced side doors working in guides |
