冶金 毕业设计 外文文献翻译 中英文：铁矿石烧结的最新进展

Recent Developments in Iron Ore Sintering Sintering is the most widely used agglomeration process for iron ores.As the blast furnace is a countercurrent process in which solids descend against a rising gas flow,it is imperative that the ferrous burden is supplied in a lumpy form.It is necessary,therefore,to agglomerate fine ores by sintering or pelletising.Pelletising is usuallypreferred in locations where low grade iron ore is mined and concentrated,particularly in North America.In other regions,natural high grade iron ores are available and sintering offer a lower cost agglomeration route.Consequently,sinteringis by far the more widelyused iron ore agglomeration process outside North America.In the past decade,the annual production of sinter worldwide has ranged from 530 to 586 Mt.Production has fallen since 1989 following the dramatic events which occurred in the Commonwealth of Independent States (CIS,previously the USSR)and other parts of Eastern Europe as their steel industries restructure.The recessionary effects in Europe and Japan have also adversely affected production,although it is expected to recover slowly soon,except in the CIS and Eastern Europe.Although alternative ironmaking processes are emerging,they are not expected to impact significantly on blast furnace production in the nest decade and possibly beyond. Consequently,sintering production should be maintained at its present level for some time to come.Production will decline in Eastern Europe and the CIS as rationalisation continus but grqwth will continue in China,Korea,and Taiwan.Sintering technology has evolved rapidly in the past decade.This has been driven by the need to:(i)decrease energy consumption following the escalation of energy costs in the 1970s;(ii)increase productivilty as older,less efficient plants are closed;(iii)reduce production costs;（iv）reduce environmental impact.In addition to reducing energy consumption,the sinter plant manager has been required to improve product quality to enable energy savings at the blast furnace.In Japan,coke breeze consumption has decreased fromabout 55 kg/t sinter (1973) to 45 kg/t sinter in 1992.Similarly,ignition energy has dropped from about 190 to below 30 MJ/t sinter at some locations.Some European plants have achieved similar reductions in coke breeze consumption,but in general have not been as successful in reducing ignition energy repuirements.Blast furnace coke consumption has also fallen in the past decade,partly to be replaced by fine coal injected through the tuyeres.Part of the coke saving,however,can be attributed to improved sinter quality,notably reducibility and high temperature properties.As the steel industry becomes more competitive,there has been mounting pressure to close older,less efficient plants under rationalisation programmes.On some sites,this has meant the closure of one or some sinter plants and that the surviving plant must increase its productivity in order to satisfy blast furnace demands.In Japan,five plants were closed between 1983 and 1987,but annual producyion was maintained constant,with a consequent increase in productivity.In 1992,the plants at Fos-sur-Mer(Sollac) in France and Kakogawa(Kobe) in Japan achieved the highest productivities of 50t m-3/day.Other ways of reducing costs have also been sought.Iron ore is a major cost component and ironmakers have sought ways to increase their intake of cheaper materials such as fine ores or concentrates and also limonitic ore such as RobeRiver.The use of the maximum amount possible of secondary materials arising on the works such as dusts, sludges, slags, etc.,has also received considerable attention.International concern for the environment has resulted in plant being installed to remove dust and some gaseous emissions from sinter plant process gas.In this respect,Japan has led yhe way with the installation of electrostatic precipitators for dust control and,more significantly,with plants to remove sulphur oxides and nitrogen oxides.Over 50% of sinter plants in Japan have installed desulphurising equipment and two plants have equipment to remove nitrogen oxides.On the other hand,in Europe only the Thyssen Stahl No.4sinter plant (Sehwelgern) has desulphurising equipment.Gas cleaning equipment is expensive and significantly increases the cost of producing sinter.Nevertheless,as legal requirements are introduced in Europe,new control equipment many have to be installedat many plants.In the to optimise the operation and produce the most consistent product,good plant control is essential.Although not discussed here,control and consistency in blending are equally important.In the granulation stage, operators determine their optimum moisture content and then use this for control purposes.Many plants have installed online,infrared(IR)analysers to monitor the moisture concent of the granulated feed.The water addition in the drum is automatically adjusted to maintain the set moisture content.Some Japanese plants use Iranalysres for all feed materials to be compensate for moisture variations at the inlet to the granulationdrum .On some plants,air permeability measurements are performed on granulated feed manually or automatically.Water addition to the drum may then be adjusted depending on the outcome of this measurement.Automatic control is preferred to manual methods since it results in a more rapid response and more consistent feed to the sinter strand.Bethlehem Steel has installed an online permeability apparatus in their feed hopper above the roll feeder at Burns Harbor. At Italsider, preignition permeability is monitored continuously online using a 4 4 m suction box installed immediately before the ignition hood.This has enabled Italsider to increase permeability by 9% since 1980.At NKK,uniformity of ignition is improved using a radiation thermometer installed on the exit side of the ignition hood.It is designed to scan the surface or the bed from side to side in a predetermined cycle.A microcomputer analyses the data and controls the positions of the gas valves in order to minimise surface temperature variation.Sinter chemistry is largely controlled by the blending process thoudgh final trim for CaOand some other elements is possible using bins in the sinter plant.Control of FeOis more complicated but usually involves a change in coke addition or possibly bed height.Chemical analysis is the usual method for determining FeO but a few plants use a magnetic permeability device such as Permagnag,developed by CRM in the late 1960s.This technique is currently in use at British Steel,s Scunthorpe Works.NKK have reported that they are using an FeO meter online atFukuyama Works.In order to complete the sintering process,the strand is operated in such a way to ensure that burnthrough usually occurs at the penultimate windbox.Traditionally,control of burnthrough location is achieved by adjusting the strand speed.Burnthrough itself is difficult to monitor so it is extrapolated from waste gas temperature measurement.Normally,the waste gas temperature is monitored using thermocouples in the last 3,4, or 5 windboxes and the strand operated with maximum temperature in the penultimate windbox.At some of the more modern plants,temperature is measured at several positions in each windbox to eliminate variations across the width of the strand.An average temperature is then used for each windbix.This system is used at Sollac,Fos-sur-Mer, sinter plant with the incorporation of an IRSID model.铁矿石烧结的最新进展烧结是最广泛使用的铁矿石造块法。