外文翻译中英文冲天炉炼铁Word文件下载.docx

1、冲天炉炼铁 学生姓名: 学 号:专 业:班 级:指导教师 :J.E. Rehder , President, Metkem Processes Ltd, Toronto ,Canada IT is well known that iron can be made by heating pellets of mixed iron ore and carbon. .There are considerable attractions to this procedure including the use of ore fines or dusts ,low-cost reduction carbo

2、n and possibility of operating economically at moderate rates of 50,000 to 300,000 ton/year .Various attempts have ,therefore ,been made to find a commercially successful route .Outlined here are the problem and a solution that is working very well at pilot plant scale . Metallurgy The basic procedu

3、re is to make a compact of finely divided iron oxide with enough carbon to completely reduce the oxide to metal ,and then to heat this compact until reaction is complete . Two course of action ,which have different results ,are possible . One is to heat the ore-carbon compacts to somewhat below thei

4、r fusion point ,to make a product of solid state reduced iron mixed with gangue and carbon ash .This can be done in a rotary kiln ,on a traveling grate or in a vertical shaft furnace ,and considerable development work has been done on the first two methods .The product can be used as blast furnace f

5、eed or can be melted and refined to steel in an arc furnace .However ,it is now clear that use of reduced pellets as blast furnace feed does not give the best economics ,and melting refining of steel must contend with the added slag volume and sulfur brought in with the reduction carbon . The other

6、course is to heat ore-carbon pellets to and through the fusion points of iron and gangue ,to produce hot metal and molten slag .This can and has been done in an arc furnace and in an induction furnace ,but the most economical way is in a fuel fired shaft furnace .The best known such furnace is a cup

7、ola ,such as is used in iron foundries .When ore-carbon pellets are charged to a cupola that is being operated under the right conditions ,hot metal and slag are readily produced and tapped with excellent recovery .This has been successfully done during a development program ,and at one stage a lean

8、 ore that produced 2 ton of slag/ton of hot metal was 1 satisfactorily handled .Scrap iron or steel is readily incorporated in the charge .The hot metal produced can be used directly in an iron foundry or converted to steel . The cupola At this point a clear distinction must be made between a cupola

9、 and a blast furnace .One is not a small or large version of the other since the modes of operation and internal conditions are quite different .In normal practice the cupola is operated solely as a heat generator to melt solid charge material ,whether iron ,bronze or stone ,and it does this with th

10、e highest thermal efficiency of any widely-used fuel-fired melting furnace .Fuel coke is burned under condition to create the maximum carbon dioxide content consistent with low oxidation losses of iron and alloys .This is normally 11 to 13% and means that more than in the blast furnace .The top gas

11、is lean but is ample in heat content to recuperatively heat combustion air to the moderate degree required . When ore-carbon pellets are charged to a cupola ,a considerable amounts of carbon monoxide is generated from the reduction reactions and enriches the top gas .The top gas also is higher in vo

12、lume due to the combustion of the increased amount of coke to supply large heat of reaction .The net result is 70,000 to 80,000 cu ft of top gas/ton of hot metal containing 25 to 30%carbon monoxide ,which gives a surplus after blast heating of about 5 MM Btu/ton of hot metal . Stock column height is

13、 relatively low ,20 to 50 ft ,and residence time is 1.0 to 1.5 hr . Blowing rate in cfm/sp ft of shaft cross section is about double that in the blast furnace ,but pressure is lower due to the shorter stock column and a higher permeability .Production rates of 4 to 5 ton of hot metal/sq ft /day appe

14、ar practical .At this stage it is not known how large the cupola can be effective in this manner .The largest existing iron melting cupola is 12.5ft ID which could represent 600 ton of hot metal/day as smelter ,but there is evidence of a dead-man and some question as to whether the cupola mode of co

15、mbustion can be maintained in this or larger cupolas . Due to lower blast pressure the cupola operated as a smelter can be tapped continuously through a siphon if desired .The cupola is also readily externally water cooled in the high temperature zone ,and is easily shut down for repair after a 3to

16、2 5-week campaign .These and other factors indicate that for example ,600 ton of hot metal/day would be more practically obtained from two 8.8 ft dia cupolas than from one of 12.5 ft dia . Hot blast and oxygen enrichment Use of hot blast saves coke in linear proportion to air temperature and also in

17、creases production rate ,but in iron melting practice about 1200F（649C） is the maximum used .This is primarily due to the cost of higher temperature air heating equipment ,but at every high air temperature there is evidence of lower combustion efficiency tuyeres .The maximum economical air temperatu

18、re for the smelting mode of operation is not presently known . Oxygen enrichment of combustion air is effective in decreasing coke consumption in iron melting and in smelting .The economy ,of course ,depend on local prices of oxygen and of coke . Both hot blast and oxygen enrichment are effective th

19、rough increase in flame （i .e ,maximum bed ）temperature ,and this is subject to different constraints in the cupola and in the blast furnace .The production of increased reducing gas by using tuyere injected fuel is useless in the cupola ,since the objective is a combination of maximum bed temperatu

20、re with maximum heat production . Agglomeration Strength requirement of ore-carbon compacts for a cupola are much less severe than for blast furnace pellets ,since the stock column is shorter and in many cases the compacts can be made at the cupola site so that handling is minimal . Pelletizing , ex

21、trusion and briquetting have all been used ,and binders are carbonates ,silicates or asphalt .The principal limitation is that the compacts ,of course ,cannot be heated for hardening above the ignition temperature of the contained carbon ,unless autoclaved .There are several systems available and th

22、ese will not be reviewed here . Economics and uses There is no question that smelting of ore-carbon compacts in a cupola is not expected to be economically competitive with the blast furnace ,or to operate in or 3 near its production rates and size ranges .However ,there does seem to be a place for

23、moderate tonnages in suitable supply situations. Ore-supply Supply of iron ore fines can be an economic problem since the iron ore industry is organized to provide pellets or lump ore in large quantity ,and obtaining 150,000ton/year of clean concentrate for example could encounter high freight costs

24、 .Mill wastes ,such as blast furnace dust and mill scale ,can ,however ,be readily handled and are in reasonable quantity .There is basis for thinking that such wastes can be turned into hot metal at lower capital and operating cost in the cupola ,than by processing over a sinter strand and through

25、a blast furnace .An added factor here is that volatile elements ,such as zinc ,should be more readily handled in the cupola than in the blast furnace . Coke It is essential to the economy of cupola operation to use coke of reasonable large lump size ,this being one of several differences from blast

26、furnace operation . If a cupola is used to smelt mill wastes in or near a steel plant ,the economic course is to use the oversize coke from the coke plant primary screen or grizzly ,since this avoids the cost of crushing to blast furnace size ,and the production of hot metal/ton of coke is higher th

27、an from a blast furnace . If the cupola is used separately from a steel plant and such coke is not available ,foundry coke must be used but at considerably higher price .Lump anthracite can be used to replace a portion of the coke charge ,and briquetted calcined petroleum coke is an excellent cupola

28、 fuel . Reduction carbon The desirable properties of the carbon to be mixed with the ore are high fixed carbon content ,good reactivity ,and low sulfur ash and volatile matter contents .These can be met by a considerable variety of relatively low cost carbons ,and this is a principle reason for good

29、 economics in smelting ore-carbon compacts in the cupola .The total fixed carbon required/ton of hot metal will be in the order of 1250 to 1500 1b, but 40 to 45%of this does not require to be coked or coke able . 4 Uses There are three areas where cupola mode smelting can be economically interesting

30、 .These are treating mill oxide wastes ,providing hot metal for direct use in iron foundries and for mini steel mills based on small oxygen vessels . Processing of mill wastes is immediately interesting because of the ready supply of raw materials ,there is activity in more than one location in deve

31、loping this route .The cost advantage will ,of course ,vary with local conditions ,such as whether an existing sinter plant is overloaded ,worn out or requiring extensive new air pollution control . Hot metal for medium size and large iron foundries can show every good economics from iron ore ,the m

32、ain uncertainly at the present time being the availability and cost of iron ore fines .This depends on location and on the interest of iron ore suppliers in such a market .There would appear to be opportunity for a considerable independent business in the manufacture and sale of ore-carbon pellets or compacts . Operation of a mini steel mill or an oxygen vessel supplied by hot metal from a cupola can be economic depending on local prices .A feasibility study on a 300,000 ton/year mill using a 35-ton ves