Explain

1.Steelmaking practice certified that, the active lime can improve the desulfurization and dephosphorization efficiency of 80%, and shorten the smelting time. It can be completely take reaction with acidic substances in the molten steel in 3-5 minutes.The lime reaction time of shaft kiln need 6-10 minutes at least.And it also improve furnace ridge above 40%. The furnace burden consumption is reduced to 5-8Kg/t steel,calculated in 10000000tons,savings annual about 15000000,production efficiency is significant.
2.Desulfurization and dephosphorization efficiency of active lime is obviously improved,the average S removal rate of steel is 34.5% ,especially for high S iron (S ≥ 0.06%), efficiency is more obvious, and the S removal agent consumption can be reduced by about 45%.
3.Steelmaking with active lime,iron material consumption can be reduced by 5-15Kg/t steel,than non-active lime.And it also can reduce the steel splash and adhesion on oxygen lance;sticky mouth;flue sticking phenomenon.
4.Lime consumption decreased: steelmaking with active lime, the consumption can reduce 20~25Kg/t steel,compared with non-active lime.And if use non-active lime,consumption is more than 65~70Kg,if use active lime, is 40~41.5Kg/t steel.
5.Steelmaking with active lime,slagging is fast,desulfurization, dephosphorization ability is significant, the production efficiency can be improved by 5%~10%. 6.Quality requirement of the active lime limestone:CaO≥52% SiO2≮2.0% MgO≮1.5%

Process and equipment

1.Raw material conveying system
Limestone, dolomite after crushing in the mine would be shipped to the factory.and by truck to the material pit,after screening,then conveying to raw material storage. Qualified lime stone particle size 10 ~ 50mm will be conveying to top silo of preheater by lifting equipment. Feed particle size is 10 ~ 50mm, discharging finished size of 5 ~ 40mm above 90%.
2.Active lime calcining system
Active lime calcining system consists of a vertical preheater, rotary kiln, cooler.
Vertical preheater:Vertical preheater is composed of a preheater body, a storage bin, a feeding pipe, hydraulic push rod device etc.. Preheater has polygonal and round using compartment partition device .Making the limestone gradually heating to avoid sharp warming burst into the kiln produces a large amount of powder, limestone decomposition rate is 30% ~ 40%, the average temperature of exhaust gas temperature is 230 ℃ ~ 260, thereby reducing the heat consumption.
Rotary kiln:rotary kiln is composed of cylinder, supporting device, transmission device,block wheel device, kiln tail and kiln head seal,and kiln head cover.The kiln body is 3.5% inclined of level,equipped with two sets supporting device, the roller bearing is the water-cooled oil lubricated bearings, and can automatically aligning with Spherical tile. Near the gear ring is also equipped with hydraulic blocking wheel,using frequency conversion motor driving kiln body, and an auxiliary driving kiln. Kiln head and kiln tail adopts spring type sealing device,using frequency conversion motor driving kiln and with preheater decomposition rate, to control effectively calcination temperature and time, reached the burning and burnt requirements.
Coal burner using coal and gas firing four channel burner. Flexible and convenient adjustment, flexible operation, each air jet velocity can be adjusted during operation, can bring up any flame in different kiln conditions, easy control of calcination temperature.
Vertical Cooler: vertical cooler is composed of cooler body, fixed screen, cooling device, electric vibrating discharging machine etc.. Vertical cooler has many cooling discharge area, each area discharging speed can be controlled separately according to material temperature; cooling air meet hot lime directly,cooling effect is well,ash temperature is low, ash temperature higher than the ambient temperature 40 ℃; cooling air after cooling lime, temperature can be preheated to more than 600℃, one part is used as second combustion air in rotary kiln, the other part is used to dry pulverized coal. Cooler is without moving parts, simple structure, good cooling effect, less equipment repair.
3.Pulverized coal preparation system
Pulverized coal preparation system is an important part of active lime rotary kiln system. There are generally two kinds of system, one is the wind swept coal mill tube mill pulverized coal preparation system with bag dust collector.The system has the advantages of convenient operation, clean environment etc.. Its production process is as follows: Block degree ≤ 25mm coal, from bucket elevator into the belt, then conveyed to coal bunker by belt, through disc feeder or electromagnetic vibration feeder that under coal bunker,the mill is a set of grinding, drying,when grinding, introducing hot air from rotary kiln system or flue gas from auxiliary combustion chamber to dry.Gas with coalcome out from coal grinding machine,in force of the exhaust pumping, enters the separator separation, coarse pulverized coal returned to the mill grinding again through automatic ash discharging valve,and the fine powder was driven into the bag dust collector in force of gas flow,to achieve powder and gas separated. Gas out from separator,the dust discharged after purification by an exhaust fan, a part of exhaust gas recycled in coal grinding mill,another part exhaust gas into the atmosphere through the chimney. Pulverized coal collected by the dust collector is discharged into the kiln coal storage bin.According to the need of coal warehouse, into the kiln front burner with a Roots blower, through the burner combustion air blower air supply for combustion, used for calcining limestone.
4.Finished product conveying system
Finished lime is conveyed to bucket elevator through chain bucket machine by cooler,then into top sieving grain silo by elevator, qualified part ≧5mm conveying to finished product bin by belt conveyer, powder≦5mm conveying to powder bin.Electric discharge valve is provided in finished product warehouse and powder bin. The main function of the finished product warehouse is for buffering measurement,the finished products should be promptly sent to the Steel Carbide factory to use reducing powdering.
5.Flue gas treatment system
High temperature flue gas from rotary kiln combustion, after the heat exchange with the limestone in preheater, the temperature dropped to 260 ℃ below,cooling through multi tube cooler and then into the high-temperature bag type dust collector.After dust collector,high temperature fan into the atmosphere through the chimney,the dust concentration is less than 30mg/Nm ³.
To meet requirements for the modernization process of active lime pre decomposition kiln production line, ensure the reliable operation of process equipment, stable process parameters, to ensure product quality, save energy, improve the production line running rate.The whole process adopt advanced technology controling, increase the DCS control on the basis of PLC control, centralized monitoring, operation and decentralized control of the main production line, control rotary kiln operating system to improve product quality and reduce consumption. To improve the reliability of electric control equipment and maintenance, to realize modernizatio of control, monitoring, operation.
6.Product quality
CaO ≥ 93, MgO ≤ 4.5, SiO2 ≤ 1, P ≤ 0.01, S ≤ 0.025 ignition loss ≤ 3, active degree ≥ 350ml ~ 380ml ≤ 1.5%, burning, burning ≤ 1.5%

Process

Qualified limestone deposited in the hopper, through hoist and transport into the top of silo.Preheater top bin, is made up of 2 level control the feeding amount, and then through the discharging tube of the limestone and uniformly distributed in the preheater each room.Limestone is heated from 1150°C to 900 ° C by kiln flue gas in preheater, about 30% decomposition, then into the rotary kiln by the hydraulic push rod,the limestone in the rotary kiln sintering is decomposed into CaO and CO2.After decomposition,limestone into cooler, the cold air is blown into the cooler cooling to 100 DEG C discharge. By 600 ° C hot air heat exchange into the kiln and gas mixing combustion.Gas mixed with cold air enter into dust collector by the fan,and through the exhaust fan into the chimney. Lime out of the cooler conveying into lime product warehouse by vibration feeding machine, chain bucket conveyor, bucket elevator, belt conveyor . According to the customer request whether screening processes....

Matching

Vertical preheater
Vertical preheater is one of the main active lime equipment, the main effect of vertical preheater is the limestone material sent to the preheater, and use high temperature exhaust gas from the kiln calcining out emissions(1150 degrees Celsius), the material in the preheater evenly heated to about 900 degrees Celsius.In the preheating process of 30%CaCO3 is under preheater decomposition, and then by the hydraulic push rod into the rotary kiln calcination, calcination process that not only makes the limestone calcination time in the kiln is greatly shortened, obtain higher activities of lime.
Vertical preheater system mainly consists of six parts
1.Feeding system: mainly including the upper house, the discharge pipe, the materials and structure that can guarantee the body feeding safety sealed in preheater, so that the outside of cold air cannot enter into preheater inside, and material feeding can use stick valve to achieve continuous or intermittent feeding.
2.Preheater: it is the most important part of ensuring the material preheated to 900 degrees Celsius, which is composed of a preheating chamber, a suspension device and a refractory lining (this does not belong to the scope of equipment design and manufacturing) and other parts. This part of the structure is mostly metal component material selection, part of the heat-resistant steel according to the needs, working at 1000~1100 degrees Celsius high temperature heat-resistant steel. In addition, the refractory lining structure has the advantages of novel design, good sealing performance, can ensure material in preheater evenly preheated and achieve preheating temperature.
3.The pushing device: mainly including pusher, frame and the connecting rod part, pusher heat-resistant steel casting or welding to become, can withstand high temperatures, with the help of electric and hydraulic system, the hydraulic push rod can be automatic control procedures followed by pushing.
4.Hydraulic system: mainly comprises an oil tank, pump, motor, electromagnetic valve, hydraulic tubing, his main role is to control the pushing device, complete the pushing action.
5.Charging room: mainly including the chute feeding chamber, charging spout, body, its main function is to the material into the rotary kiln preheated calcined within.
6.Framework: It includes columns, ring beams , the main role is to carry the upper structure of the preheater

Technical

main equipment