Silicate slag

The gases from the kiln contain about 9% sulphur dioxide. (The calcium oxide combines with the silica to form a silicate slag which, when cool, is crushed and mixed with some anhydrite to give cement, a valuable by-product.)... 

The evolution of gases, such as in dre example given above of dre formation of CO(g) in dre U airsfer of sulphur between carbon-saturated iron and a silicate slag, requires dre nucleation of bubbles before dre gas can be eliminated from the melt. The possibility of homogeneous nucleation seems unlikely, and the more probable source of gas bubbles would either be at the container ceramic walls, or on detached solid particles of the containing material which are... 

Similarly tire removal of phosphorus from liquid iron in a silicate slag may be represented by the equations... 

Ca +, Fe + etc. which are the cationic species in the slag phase). Fellner and Krohn (1969) have shown that the removal of phosphorus from iron-calcium silicate slags is accurately described by the Flood-Grjotheim equation widr... 

Masson C. R. (1972). Thermodynamics and constitution of silicate slags. Jour. Iron Steel Inst, 210 89-96. 

Toop G. W. and Samis C. S. (1962a). Some new ionic concepts of silicate slags. Can. Met. Quart, 1 129-152. 

The fibrous glass used for insulation materials does not require starting materials of high purity. Beach sand, which consists largely of the mineral quartz, is easily obtainable and quite inexpensive. Alternatively, silicate slags or waste rock from mining can be melted and processed to create the products called rock-, slag-, and mineral-wool. Such materials are used for insulation. Where specific properties are desired, such as resistance to ultra-... 

Table 5.1 summarizes the uses of lime. Lime is used as a basic flux in the manufacture of steel. Silicon dioxide is a common impurity in iron ore that cannot be melted unless it combines with another substance first to convert it to a more fluid lava called slag. Silicon dioxide is a Lewis acid and therefore it reacts with the Lewis base lime. The molten silicate slag is less dense than the molten iron and collects at the top of the reactor, where it can be drawn off. Over 100 lb of lime must be used to manufacture a ton of steel. 

Lighter mixed silicate slag floats over the denser, molten copper(I) sulfide. Slag is drained off from time to time. Molten CU2S is transferred to a Bessmer converter where it is air oxidized at elevated temperatures producing metallic copper and sulfur dioxide ... 

The molten matte layer is transferred to a converter, where air is blown through it and sand is added so that the FeS forms a silicate slag... 

Native copper ore is crushed, concentrated by washing with water, smelted, and cast into bars. Oxide and carbonate ores are treated with carhon in a smeller. Sulfide ore treatment is complex, hut. in brief, consists of smelling to a matte of cuprous sulfide, ferrous sulfide, and silica, which molten matte is treated in a converter by the addition of lime and air is forced under pressure through the mass. The products are blister copper, ferrous calcium silicate slag, and SO . Refining is conducted by electrolysis, and the anode mud is treated to obtain the gold and silver. See Fig. I. 

The ore is crushed and ground in.ball mills to pass through a 30-mesh sieve. It is mixed with suitable fluxes (limestone and quartz) and smelted in small blast-furnaces having a capacity of 25 to 30 tons per twenty-four hours. The products obtained are (i) flue dust, which is returned to the furnaces, and crude arsenious oxide, which is resublimed and sold (ii) a silicate slag, which is thrown away unless it contains more than 10 ounces of silver per ton (iii) crude silver bullion, which is mechanically detached and cupelled to a fineness of 994 before it is sold to silver refiners and (iv) a speiss of cobalt, nickel, iron, and copper arsenides, containing considerable amounts of silver. The crude silver bullion contains about three-fourths of the silver present in the ore. 

These disadvantages make fusion a less than ideal technique for extreme trace element determination. However, for the determination of major, minor, and even some trace elements in such matrices as fly ash, silicates, slags, and dust good results can be obtained. 

The sulphide ore is oxidised in the presence of silica which enables the iron to be removed as a silicate slag. The nickel oxide left is reduced at 350° by water gas to an impure metal leaving the iron as ferric oxide. Purification is based on the formation and decomposition of gaseous Ni(CO)4. Carbon monoxide is passed over the impure metal at 60° and the gas containing a few per cent of the tetracarbonyl is brought into contact with agitated nickel pellets at 200°. The pellets grow as nickel is deposited on them the CO is recirculated (Fig. 258). 

The feed shutes for the raw materials are positioned symmetrically round the electrodes. The tap-hole for the ferrophosphorus is positioned right at the bottom of the reactor, with the tap-hole for the less dense calcium silicate slag just above it. Carbon monoxide and phosphorus vapor leave by the gas outlet at the top of the reactor. 

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