New developments in iron making 炼铁的新发展During the past century, many efforts were made to develop processes for producing iron for steelmaking that could serve as alternatives to the conventional blast furnace.在过去的一个多世纪里，为了找到能够取代传统高炉的炼铁技术人类做了许多努力。
This chapter presents a review of the alternativels processes that have achidved some measure of commercial success.本章将介绍成功商用于工业化炼铁体中的一些新工艺和新技术。
1.Direct reduction technology 1. 直接还原技术In the history of iron and steelmaking technology, the first process is the direct reduction process. 在钢铁冶炼技术的历史上，最早使用的就是直接还原法。
The blast furnace takes the place of the direct reduction process, which is the greteat imtronvement in the metallurgical technology. 高炉取代了直接还原法炼铁是冶金技术的重大进步。
With the development of iron and steel industry, coke, on which blast furnace have depended for over 200 years, is becoming more expensive every expensive every year, and supplies of suitable coking coals are becoming scarcer. 随着钢铁工业的发展，200多年以来高炉一直使用的焦炭，价格每年都在增加，合适的焦煤越来越少。
The direct reduction process was brought back at the end of the eighteenth century. 在18 世纪末，直接还原法又得以恢复。
Today, technology that produce iron by reduction of iron ore below the melting point of the iron producde is generally classified as direct reduction processes and the products referred to as direct reduced iron(DRI). 现在那些在低于铁的熔点温度以下用还原铁矿石的方法来冶金的技术通常称为直接还原法，其产品称为直接还原铁（DRI）。
According to the reducing agents used, direct reduction technology is commonly classed into two types: gas reduction processes and reduction processes with solid reducing agents. 根据还原剂的使用种类，直接还原法一般可分为气体还原法与固体还原法两类。
According to the types of reduction reactors used, it is also classified into four main processes----fluidized bed, shaft furnace, retort, rotary kilin processes. 按使用的还原反应器类型，直接还原法主要分为流化床、竖炉、反应罐和回转窑法四大类。
(1)gas reduction processes （1）气体还原法Reducing gases are carbon monoxide hydrogen or mixtures of two in gas reduction process. 在气体还原法中，还原剂是一氧化碳，氢气或这两种气体的混合物。
They are normally obtained from natural gas. 它们通常从天然气中获得。
The carbon monoxide and hydrogen are generated in the methane steam of natural gas reforming processes according to the reaction: CH4+H2O=CO+3H2天然气中甲烷转化为一氧化碳和氢气的反应如下: CH4+H2O=CO+3H2The shaft-furnace process plays an important part in gas reduction processes. 竖炉法在气体还原法中起着重要的作用。
More than 50% of all reduction processes are carried out in a shaft-furnace. For example, the Midrex process is a typical(Fig.5-1). 50％以上的还原过程是在竖炉中进行的，例如米德列法就是一个代表(图5-1)。
Midrex furnace has developed into a main production from of direct reduction processes, since the first steel plant was built and went into production in 1969. 米德列竖炉自1969年最早建成并投产以来，已发展成为直接还原去的主要形式。
The largest Midrex furnace has an annual capacity of 800,000 ton. 最大的米德列紧炉年生产能力达到了80 万吨。
The main components of the process are the shaft furnace, the gas reformer, and系统。
Reducing gas enters the reducing furnace through a bustle pipe at the bottom of the reduction zone and flows countercurrent to the descending solids. 生产时，还原气通过位于还原带底部的环形风管进入到还原炉内，迎着下降炉料向上运动。
The charge solids flow continuously into the top of the furnace through seal legs. 固体炉料通料封管不断从竖炉顶部进入。
The reduction furnace is designed for uniform mass movement of the burdn by gravity feed, through the preheating, reduction, and cooling zones of the furnace. 还原炉的设计使得炉料能够依靠自身的重力作用均匀地通过预热带、还原带、冷却带。
The cooled DRI is continuously discharged through seal legs at the bottom of the furnace. 冷却后的直接还原铁可以不断地通过炉底料封管排出。
Cooling gases flow countercurrent to the burden in the cooling zone of the shaft furnace. 冷却气体的流向与竖炉内冷却带炉料的流向相反。
The reducing top gas flows from an outlet pipe into the top-gas scrubber where it is cooled and its dust particles are removed. 从炉顶逸出的气体流向洗涤器，在那里冷却，洗涤除去炉尘。
The largest portion of the top gas is recompressed, edriched with natural gas, preheated to about 400o C, and piped into the reformer tubes. In the catalyst tubes, the gas mixture is reformed to carbon monoxide and hydrogen. The hot reformed gas is then recycled to the DR furnace. 大部分炉顶气体被压缩后与天然气混合预热到约400o C，导入重整管，被重整成一氧化碳和氢气，然后循环到直接还原炉内。
(2) reduction processes with solid reducing agents （2）固体还原法The solid reducing agents are coals of any granulation and composition in direct reduction processes. 固体还原法使用的还原剂是呈粒化状态的煤和合成的煤。
Rotary kiln furnace is important equipment used solid reducing agents. This process operates in a continuously materials flow. 回转窑是使用固体还原剂的重要设备，这个工艺是连续生产的。
The mature processes in coal-based direct reduction are German SL/RN process, british DRC process and French Codir process. 目前，煤基直接还原流程成熟的工艺是德国的SL/RN法，英国的DRC 法和法国的Codir 法。