一步法回转窑生产还原铁热压块项目

One-step Rotary Kiln Producing Reducing Iron Hot-pressing Block Project

工艺说明

Technical proposal

一、工艺简介

       Introduction of the Process

       1、还原铁热压块(HBI)生产工艺

             Production Process of Reduced Iron Hot-pressing Block (HBI)

用天然气或煤气做热源的回转窑还原技术+热压成型钝化机压块是我公司最新研发生产还原铁热压块新工艺技术，新工艺节能环保，已经申报国家发明专利。我公司研发的回转窑+热压成型钝化工艺，与传统工艺有了很大改进，用天然气或煤气做热源，用CO气体和无烟煤做还原剂，不但回转窑操作变得简单，回转窑结圈几率降低，运行更可靠，同时由于增加了热压成型钝化系统，最大限度防止了再氧化和利用了余热，降低了能耗和生产成本。

Rotary kiln reduction technology with natural gas or gas as heat source and passivator pressing block by hot pressing are the latest research and development of new technology for producing reduction iron hot pressing block by our company. The new technology is energy-saving and environmental protection, and has declared the national invention patent. It not only makes rotary kiln operation easy, Rotation kiln ringing rate becomes lower and the operation is more reliable. At the same time, due to the addition of passivation system for hot pressing forming, the waste heat is maximally utilized, and the energy consumption and production cost are reduced.

该工艺主要针对铁矿粉或氧化铁皮进行还原，所用原料有铁矿粉（氧化铁皮）、还原剂（CO+无烟煤）及脱硫剂。主要设备包括配料压球系统、烘干加热系统、二次燃烧室系统、回转窑还原系统、热压成型钝化系统、尾气抽风净化系统、喷煤系统和循环水冷却系统等。

The process is mainly aimed at reducing iron ore powder or oxide scale. The raw materials used are iron ore powder (oxide scale), reducing agent (CO + anthracite) and desulfurizer. The main equipments include batching and ball-pressing system, drying heating system, secondary combustion chamber system, rotary kiln reduction system, hot pressing passivation system, exhaust air purification system, coal injection system and circulating water cooling system etc.

主要工艺流程是铁粉、氧化铁皮、粘结剂按一定比例混合后，通过皮带机输送到强制混料机中，经过强制搅拌混合的料通过皮带机进入储料仓中，储料仓4个，下面安装有圆盘给料机，可根据压球机产量调节圆盘给料机给料量，铁粉料通过皮带机加到压球机中，压球机压好的球，通过皮带机进入链板式烘干机中。铁粉球在链板式烘干机中被来自烧结回转窑的热风烘干加热，二次燃烧室排出的高温尾气直接进入烧结回转窑，烧结回转窑烧结的球团,温度高达11０0℃，密闭送进还原回转窑中进行加热还原，经回转窑还原的高温还原球团在窑头出料口进行筛分，筛下物加湿降温后有螺旋上料机排出，费焦经处理后，颗粒料可以继续使用。筛上的热还原球团经压块机进行热压钝化处理，最终出还原铁热压块（HBI）产品。

The main process is that after mixing iron powder, iron oxide scale and binder in a certain proportion, the material is conveyed to the forced mixer through belt conveyor. After forced mixing, the material is entered into the storage bin through belt conveyor. There are four storage silos with disc feeders installed below. The feeding quantity of disc feeder can be adjusted according to the output of ball press. Iron powder is added to the ball press through belt conveyor. The ball pressed by the machine enters the chain plate dryer through the belt conveyor. Iron powder pellets are heated by hot air drying from sintering rotary kiln in chain plate dryer. The high temperature tail gas from secondary combustion chamber enters sintering rotary kiln directly. The sintered pellets in sintering rotary kiln are fed to reduction rotary kiln at a temperature as high as 1100 C. The high temperature reduction pellets reduced by rotary kiln are screened at the outlet of kiln head, and the sieve material is humidified and cooled. The screw feeder discharges the coke, after treatment, the granular material can continue to use. The hot reduction pellets on the sieve were passivated by hot pressing with a compactor, and the reduced iron hot pressing block (HBI) product was finally produced.

2、设备工艺布置图

          Equipment Process Layout

   3、天然气回转窑还原技术+热压成型钝化工艺主要特点

    The Features of Reduction Technology + Hot Pressing Passivation Technology for Natural Gas Rotary Kiln

 用天然气或煤气做热源的回转窑还原技术，再配加二次燃烧室+成品筛分热压块以后，生产工艺与传统的回转窑艺有了很大的区别。

 Reduction technology of rotary kiln using natural gas or gas as heat source and adding secondary combustion chamber + finished product sieving hot pressing block, the production process is quite different from the traditional rotary kiln process.

 1）、回转窑长度变短，一般在40m-60m左右,使投资减少；同时由于回转窑变短，回转窑热平衡极易建立，操作变得简单。由于物料在窑内时间变短，同时由于还原采用无烟煤颗粒，强度好，摩擦产生的粉末减少，使窑炉炉衬结圈几率降低 ，设备运行更可靠；

      1）、The length of the rotary kiln becomes shorter, generally about 40m-60m, so that the investment is reduced; at the same time, as the rotary kiln becomes shorter, the heat balance of the rotary kiln can be easily established and the operation becomes easier. As the material in the kiln becomes shorter, at the same time, anthracite particles are used for reduction., the iron powder produced by the friction is reduced, so that the kiln furnace liner lining is less likely to be ringed, and the equipment operation is more reliable.

      2）、特殊的加热燃烧和喷煤方式及回转窑二次风机，使回转窑内温度均匀，还原区温度基本在1100℃～1150℃；

The special coal injection method and secondary fan of rotary kiln make the temperature of the short rotary kiln uniform and the kiln tail temperature reaching 1100 ~ 1150 degrees;

 3）、由于尾气中富含煤气，设立二次燃烧室可以燃烧掉尾气中的CO等可燃成分，不仅可以使尾风温度提高到1150℃，而且利用尾风也可保证安全可靠；

Because the exhaust gas is rich in gas, setting up a secondary combustion chamber can burn off the combustible components such as CO in the exhaust gas, which can not only raise the temperature of the exhaust to 1150 C, but also ensure the safety and reliability of the exhaust.

 4）、回转窑排出的混合还原料，经特制高温震动筛处理后，纯净高温还原球团直接进入热料压机热压钝化处理，热压块密度可达6.5-6.8t/m3；

the mixed reducing material discharged from rotary kiln is treated by special high temperature shaking screen. The pure high temperature reducing pellet is directly passivated by hot pressing machine. The density of hot pressing pellet can reach 6.5-6.8t/m.

5）、对筛分出的废焦进行处理，大于2mm颗粒可以继续使用，减少了还原剂使用量，降低生产成本；

The sifted waste coke can be treated, and particles larger than 2mm can be used continuously, which reduces the amount of reductant used and reduces the production cost.

      6）、用天然气或煤气作为热源，CO+煤炭颗粒还原，尾气含尘量大大降低，经除尘器处理后完全可以达到规定的尾气排放标准。

Natural gas or gas is used as heat source and CO + coal particles are reduced, the dust content of tail gas is greatly reduced, and the tail gas can completely meet the prescribed emission standard after being treated by dust collector.

 7）、二次燃烧室将尾气中可燃成分燃烧后排出的高温尾气首先进入烧结回转窑对球团加热烧结，然后再进入链板式加热器对冷球团进行烘干，最大限度利用热能，提高能源利用率，降低成本。

The high-temperature exhaust gas from the combustible components in the tail gas of the secondary combustion chamber first enters the sintering rotary kiln to heat and sinter the pellets, and then enters the chain-plate heater to dry the cold pellets, so as to maximize the use of heat energy, improve the utilization rate of energy and reduce costs.

4、原材料工艺要求

The requirement of the raw material

 1）铁粉（铁矿石）

Iron powder

   铁粉TFe≥68%，粒度＞80目

    Iron powder TFe≥68%, particle size>80 mesh

  2）还原剂

Reducing agent

    本项目还原剂为无烟煤，每吨球团需要450Kg，无烟煤粒度为10mm-20mm.

   The reducing agent of this project is anthracite. Each ton of pellets needs to 450 Kg. Anthracite particle size is 10 mm-20 mm.

    3）石灰石

    Limestone

    CaO含量＞55%，粒度小于5mm

    CaO content > 55%, particle size less than 5 mm

     4）天然气

    Natural gas

     天然气热值＞8000大卡

    Calorific value of natural gas > 8000 calories

 5、产品要求

     Product requirement

1）、金属化率

metallization rate

产品平均金属化率90%-92%，含碳量0.5-1%

The average metallization rate of products is 90%-92%, and the carbon content is 0.5-1%.

1）      产品形状

Shape of the product

    产品为直接还原铁热压块（MBI），还原铁块外形为直径200-220mm,高度150-200mm的圆柱体，密度6.0-6.5t/m3。

The product is directly reduced iron hot pressing block (HBI). The shape of reduction iron block is a cylinder with diameter of 200-220 mm and height of 150-200 mm. Its density is 6.0-6.5 t/m

　二．各系统工艺要求

          Technological requirements of each system

          1．  配料压球系统

       Batching and Ball-pressing system

铁粉、氧化铁皮、粘结剂分别装入给料仓，通过可调给料机、皮

带秤将三种原料按照工艺要求比例给入混料皮带，由混料皮带机将混合料装入强制混料机中进行搅拌。搅拌混合均匀的料进入储料仓，通过圆盘给料机和皮带机将搅拌好的料送到高压压球机，用高压压球机将铁粉料压成冷固球团，形状为扁圆形，尺寸φ30*20mm, 冷固球团由皮带机送到链板烘干机进行烘干预热。

Iron powder, iron oxide scale and binder are respectively loaded into the feeding bin, and three kinds of raw materials are proportionally fed into the mixing belt according to the technological requirements by adjustable feeder and belt conveyer. The belt conveyor loads the mixture into the forced mixer for mixing. Mixing uniform material into the storage bin, through the disc feeder and belt conveyor, the mixing material is sent to the high-pressure ball presser. The iron powder is pressed into cold-solidified pellets by high-pressure ball presser. The shape of the pellets is flat circular and the size isφ30*20mm. The cold-solidified pellets are sent by belt conveyor to chain plate dryer for heating intervention.

    2．  链板式烘干机

     Chain plate dryer

     链板烘干机分成１０个风箱，分为烘干段加热段，烘干段6个风室，预热段４个风室。

     Chain plate dryer is divided into 10 bellows, which are divided into heating section of drying section, 6 air chambers of drying section and 4 air chambers of preheating section.

       2.1烘干段

            drying section

含水8%左右的合格冷压球在烘干段内，首先被从烘干机预热风箱引来的热气进行抽风干燥。为了保证含大量水分的冷压球球在烘干段内不发生爆裂，要求热气温度，前3个风箱应严格控制在300℃以下，后3个风箱400℃-500℃。对料层进行干燥，使冷压球团脱水、干燥、升温。

In the drying section, the qualified cold-pressed balls with about 8% water content are first pumped and dried by hot air from the preheater of the dryer. In order to ensure that the cold-pressed ball with a lot of water does not burst in the drying section, the temperature of hot air is required. The first three bellows should be strictly controlled below 300 C, and the last three bellows should be controlled between 400 C and 500 C. The material layer is dried to dehydrate, dry and heat the cold-pressed pellets.

从风箱抽出的废热气，经电除尘和脱硫处理后，由主抽风机经烟囱排入大气。烘干段长度18米。

The exhaust hot gas extracted from the bellows is treated by electrostatic precipitation and desulfurization, and is discharged into the atmosphere by the main exhaust fan through the chimney. The length of drying section is 18 meters.

      2.2预热段

            preheating section

在预热段，５０0℃-６５0℃热气流通过料层使生球继续升温。

预热段主要热源为来自烧结回转窑排出的热风，回风由回热风机打入烘干段。回热风机进风端和出风端都安装热电偶，回热风机进风端热电偶前能够补冷风，补风量可调，以确保回热风机进风不得超过550℃。

   In the preheating stage, the hot air flow from 500 ~650 ℃passes through the material layer to keep the green balls warming up.

The main heat source in the preheating section is the hot air discharged from the sintering rotary kiln, and the return air is driven into the drying section by the regenerative fan. Thermocouples are installed at both the inlet and outlet ends of the regenerative fan. Before the thermocouples at the inlet end of the regenerative fan, the cooling air can be compensated and the air supply volume can be adjusted to ensure that the inlet air of the regenerative fan cannot exceed 550 ℃.

回热风机温度不超550℃，风压5600Pa。

    The temperature of the regenerative fan does not exceed 550 C and the air pressure is 5600Pa.

预热段长度１２米。

 The length of preheating section is 12 meters.

烘干预热后的冷压球团通过输送机密闭进入烧结回转窑进行加热，溜料管安装溜筛，筛出小于５mm碎料，碎料送到搅拌机重新搅拌。链板烘干机排出的尾气低于220℃，经过布袋除尘器除尘后由主抽风机打入烟筒排放。

After baking, the cold-pressed pellets are heated in the sintering rotary kiln by conveying confidentially. The chute pipe is equipped with a chute, and the crushed materials less than 5 mm are screened out. The crushed materials are sent to the mixer for re-stirring. The tail gas discharged by chain plate dryer is below 220 C, which is discharged by the main exhaust fan into the chimney after dust removal by bag filter.

3、烧结回转窑

 Sintering rotary kiln

二次燃烧室热风温度在1１５0℃，直接进入烧结回转窑，对球团进行加热烧结，提高球团强度。烧结回转窑排出的热风，直接进入链板烘干机预热段，烧结回转窑排出的热球团（温度达到１０５0℃）密闭进入还原回转窑。

The hot air temperature in the secondary combustion chamber is 1150 C, and the pellets are directly heated and sintered in the sintering rotary kiln to improve the strength of the pellets. The hot air discharged from the sintering rotary kiln directly enters the preheating section of the chain dryer, and the hot pellets discharged from the sintering rotary kiln (temperature up to 1050 C) are sealed into the reduction rotary kiln.

4、二次燃烧室系统

Secondary Combustor System

回转窑排出的热风，温度约１００0℃，密闭进入二次燃烧室燃烧，。排出的烟气温度约1１５0℃,高温烟气进入烧结回转窑对球团进行加热烧结，同时二次燃烧室还有对尾气沉淀除尘功能

The hot air discharged from the rotary kiln, with a temperature of about 1000 C, enters the secondary combustion chamber and combusts in an airtight way. The exhaust flue gas temperature is about 1150 C. The high temperature flue gas enters the sintering rotary kiln to heat and sinter the pellets. At the same time, the secondary combustion chamber has the function of precipitation and dust removal of the tail gas.

二次燃烧室安装有助燃风机，风量可调，在二次燃烧室上有三排烧嘴，用于烧点回转窑尾气中的CO等可燃气体，提高尾气温度，避免后续工序操作隐患。

The secondary combustion chamber is equipped with a combustion-supporting fan with adjustable air flow. There are three rows of burners in the secondary combustion chamber for burning combustible gases such as CO in the tail gas of rotary kiln, so as to raise the tail temperature and avoid the hidden dangers in the subsequent operation.

二次燃烧室出口安装尾气取气点，随时观察进出二次燃烧室气体中CO和O2含量，以便更好调整助燃风机风量，保证CO全部燃烧掉。

The exhaust gas intake point is installed at the outlet of the secondary combustor, and the CO and O2 contents in the gas entering and leaving the secondary combustor are observed at any time, so as to better adjust the air flow of the combustion-supporting fan and ensure that all CO is burned out.

二次燃烧室进出口安装有测温点，在操作室和中控室随时可观察进风和出风温度。

Temperature measuring points are installed at the inlet and outlet of the secondary combustion chamber. The inlet and outlet temperatures can be observed at any time in the operation room and the central control room.

烧结回转窑多余热风由换热风机牵引进入换热器，换出的热风温度可达４００℃，用作还原回转窑、二次燃烧室及烧结回转窑助燃风，换热后的尾风，温度约５００℃，由换热风机打进烘干机，对铁粉进行烘干，最大限度利用热能。

The excess heat air of sintering rotary kiln is pulled into the heat exchanger by the heat exchanger fan, and the temperature of the hot air exchanged can reach 400 C. It can be used as the combustion-supporting air of reduction rotary kiln, secondary combustion chamber and sintering rotary kiln. The tail air after heat exchange has a temperature of about 500 C. It is driven into the dryer by the heat exchanger fan to dry the iron powder and maximize the use of heat energy.

5、回转窑还原系统

Rotary kiln reduction system

烧结后的冷压球团（或铁矿石）从烧结回转窑经过溜槽进入还原回转窑，并随回转窑沿周边翻滚同时沿轴向朝窑头移动，并在折返线的作用下部分返回一定距离，以此延长留窑时间。回转窑烘窑、加热用天然气做热源，窑内温度达到1000℃时开始喷煤并开始给料。

The sintered cold-pressed pellets (or iron ore) enter the reduction rotary kiln through chute from the sintering rotary kiln, roll along the periphery of the rotary kiln and move along the axis of the kiln head, and return to a certain distance under the action of the return line, thus prolonging the kiln retention time. Gas is used as heat source for drying and heating of rotary kiln. Coal injection and feeding are started when the temperature in the kiln reaches 1000 C.

在窑头装有专门设计的天然气烧嘴，通过调整助燃风量和天然气量，调节控制天然气燃烧和火焰形状，对窑内物料进行加热。同时窑头还装有２只兰碳喷枪，在回转窑正常工作时使用。

A specially designed natural gas burner is installed at the kiln head to heat the material in the kiln by adjusting the amount of combustion air and natural gas, adjusting and controlling the combustion and flame shape of natural gas. At the same time, the kiln head is equipped with two blue carbon spraying guns, which can be used in the normal operation of the rotary kiln.

回转窑开始加料后，由粒煤喷枪在窑头喷入粒度10～20mm的煤碳，喷吹量为：300kg-400kg/吨球团。

After feeding in rotary kiln, coal with particle size of 10-20 mm was injected into the kiln head by granular coal spray gun, and the injection amount was 300 kg-400 kg/ton pellets.

在窑尾配加粒度1～１０mm的回收焦丁，配加量50～100kg/吨球团。

In the end of the kiln, the recovered coke butadiene with particle size of 1-10 mm is added, and the dosage is 50-100 kg/ton pellets.

球团在窑内主要受热辐射作用，边翻滚边还原。球团还原温度1060～1150℃，靠二次风和天然气量来调整温度。窑体温度监测点位７个，采用有线传输测温。

The pellets in the kiln are mainly subjected to heat radiation and are reduced by rolling. The reduction temperature of pellets ranges from 1060 to 1150 C. The temperature is adjusted by secondary wind and natural gas. There are 7 monitoring points for kiln temperature, which are measured by wired transmission.

窑体风机７个，风压2000Pa。喷吹风管由特殊耐热钢铸造，安装时考虑拆卸方便。窑体二次风机给风的风量可调，确保回转窑内还原温度。

There are 7 kiln blowers with air pressure of 2000 Pa. The injection air duct is cast by special heat-resistant steel. It is easy to disassemble when it is installed. The air flow rate of the secondary fan in the kiln body can be adjusted to ensure the reduction temperature in the rotary kiln.

喷枪与测温系统连锁，可以自动控制，也可以手动控制。

The spray gun is interlinked with the temperature system, which can be controlled automatically or manually.

窑头和窑尾罩采用新型密封装置。

New sealing devices are used for kiln head and kiln tail cover.

还原球团通过回转窑窑头罩内溜槽和固定筛卸到保温箱内。

Reduced pellets are discharged into the insulating box through chutes and fixed sieves in the head cover of rotary kiln.

根据产量要求选用回转窑型号，进料和出料端为减小耐材重量，用钢板收口，收口处耐材厚度3５0mm。球团在回转窑中停留时间约７h。回转窑选择变频调速电机调速。

Rotary kiln type is selected according to the output requirement. In order to reduce the weight of refractories at the feed and discharge ends, steel plate is used to close the inlet and the thickness of refractories at the closure is 350 mm. The residence time of pellets in rotary kiln is about 7 hours. The rotary kiln chooses variable frequency speed regulating motor to speed up.

6、热压成型钝化系统

Passivation System for Hot Press Forming

还原高温球团通过回转窑窑头罩内溜槽进入保温箱内，经特质高温震动筛筛分，将>15mm还原球团筛出，设计时要考虑溜筛角度，使其容易流料，＜15mm尾料料流入降温设备，由风力输送系统送到尾料处理场。

Reduced high temperature pellets enter the incubator through the chute in the head cover of rotary kiln. After screening by special high temperature vibration, the reduction pellets > 15mm are screened out. The angle of the sieve angle should be considered in the design to make it easy to flow. The less than 15mm tailings flow into the cooling equipment and are sent to the tailings disposal yard by the wind power conveying system.

>15mm高温还原球经卷扬提升后，在高温状态下，液压压块机压成25Kg左右热压还原铁块，由铲车运至成品压块场地。

   After hoisting and lifting the >15mm high temperature reduction ball, under the high temperature condition, the hydraulic press presses the reduction iron block into about 25kg hot pressure, which is transported by forklift truck to the finished product pressing site.

7、尾气抽风净化系统

Exhaust air purification system

链板式烘干机排出的热废气，经除尘器除尘后由主抽风机打入脱硫系统，脱硫处理后经烟囱排入大气。烟气温度大于150℃，最高温度220℃，风量２０万m3（工况），风压5６00Pa,含尘浓度100mg/ N m3。

The hot exhaust gas discharged by chain plate dryer is pumped into the desulfurization system by the main exhaust fan after dust removal by the dust collector, and then discharged into the atmosphere by the chimney after desulfurization treatment. The flue gas temperature is over 150 C, the highest temperature is 220 C, the air volume is 200,000 m3 (working condition), the air pressure is 5600 Pa, and the dust concentration is 100 mg/N M.

排出烟气灰尘浓度小于30mg/Nm3，H2S气体含量小于10mg/ Nm3,

SO2气体含量不得超过800ppm。

The exhaust dust concentration is less than 30mg/Nm and the H2S content is less than 10mg/Nm., SO2 content should not exceed 800 ppm.

除尘器及风机入口设计测温点，在操作室和中控室能随时监测尾气温。

Temperature measuring points is designed for dust collector and fan entrance can monitor tail temperature in operation room and central control room at any time.

设计中风机进、出口与连接管道间采用了软连接，风机出口管道上设有管道消声器，用以控制风机噪声，以满足《工业企业噪声控制设计规范》的要求。

Soft connection is adopted between the inlet and outlet of the fan and the connecting pipes in the design. A pipe muffler is installed on the outlet pipes of the fan to control the noise of the fan, so as to meet the requirements of the Code for the Design of Noise Control in Industrial Enterprises.

8、尾料加工系统

Tailings processing system

筛下废兰炭经过加湿降温后，由风力输送系统送到尾料处理场。颗粒料收到颗粒料仓内，细粉由布袋除尘器收集。经磁选处理后颗粒料可以加入回转窑做还原剂重新回收利用。

After humidification and cooling, the waste orchid charcoal is sent to the tailings treatment plant by the wind conveying system. The granular material is received in the granular silo, and the fine powder is collected by the bag filter. After magnetic separation, granular material can be added to rotary kiln as reductant and recycled.

三、制造成本

Manufacturing cost                         

                        单位：  /吨海绵铁

UNIT:    /T Sponge Iron