| 摘要 |
<p>1,149, 760. Extracting metals. IMPERIAL SMELTING CORP. (N. S. C. ) Ltd. June 23, 1967 [July5, 1966], No.30091/66. Heading C7D. In a method of improving the operating efficiency of a zinc-lead blast furnace into which are charged coke and a sinter containing zinc oxide and lead oxide, pre-heated oxygen-containing gas being blown in through tuyeres near the bottom of the furnace, while below these tuyeres molten lead and slag are run off, the zinc oxide in the charge being reduced to zinc vapour which is taken off and condensed, the ratio of zinc to carbon in the charge and the pre-heat temperature of the blast are controlled according to the continually monitored values of (1) the said zinc/carbon ratio (2) the said pre-heat temperature (3) the ratio of slag-forming materials to carbon in the charge (4) the composition of the furnace gases (5) the zinc content of the slag (6) the temperature of the molten slag leaving the furnace, the valves (1) to (6) being converted to electrical signals and fed continuously into a computer which operates to effect control of the first two values. This control is effected to maximize profitability according to the formula: - PF = 3À764*10<SP>-4</SP>D (p+1) L(L 1 E*10<SP>-2</SP>+PL 2 R*10<SP>-2</SP> - EL 6 ,* 10<SP>-2</SP> - L 8 P (pp+R)<SP>*</SP> 10<SP>-2</SP> - 100M/Zs) - ZW(L 1 E*10<SP>-4</SP> +L 6 *10<SP>-2</SP> L 6 E*10<SP>-4</SP>) - 10<SP>2</SP> C/D (100-f)] in which PF = profit in ú / hour per unit blast rate E = condensation efficiency -% R = recovery of lead in bullion -% pp = loss of lead in slag and cast zinc (as % of lead in sinter input) p = ratio of lead/zinc in sinter Zs = % zinc content of sinter ZW = % zinc input lost in slag D = ratio of zinc/ carbon in charge f = % ash in coke L 1 = value of zinc produced - ú /ton L 2 = value of lead produced - ú /ton L 6 = cost of zinc in sinter - ú /ton L 8 = cost of lead in sinter - ú /ton M = cost of sintering - ú /ton C = cost of coke - ú /ton (p+1) = carbon burnt - mols/atom of oxygen in blast.</p> |
