This paper introduces the technical status quo and characteristics of the mechanized lime shaft kiln with mixed fuel,higher requirements are put forward for the scientific structure of the furnace,the technological features of the material distribution technology,the relevance of the lower ash discharge and sealing,the air supply for the furnace and the control of the flue gas,the production management and development prospect of the mixed-fuel mechanized shaft kiln are also discussed.

Calcium carbide slag is a kind of waste residue with calcium dihydroxide as the main component after acetylene gas is obtained by hydrolysis of calcium carbide.In this paper,the characteristics of calcium carbide slag and the problems of fine particle size (about 80% particle size in 10~50  μm),high calcium content ［Ca(OH)2 content ≥90%］,high moisture content (about 35%) and high harmful composition of calcium carbide slag are studied,and a series of experimental studies were carried out.The experimental results show that the calcined CaO has high activity and can be used as raw material for calcium carbide production.However,due to its high impurity content,it is necessary to use CaO in combination with the calcined active lime of natural limestone to reduce the influence of harmful components on calcium carbide furnace,the proportion of the mixture can reach about 20%.Based on the characteristics of calcium carbide slag and the experimental results,a complete technical route (suspension calcination) for the preparation of active calcium oxide from calcium carbide slag is proposed.

This paper introduces the technical characteristics and innovation of active lime rotary kiln，as well as the some innovations in energy saving，environmental protection and comprehensive utilization of resources of active lime rotary kiln.

The effects of transition metal Fe powder and Ni powder on the microstructure of low carbon MgO-C refractories at different heat treatment temperatures were studied.The results showed that the addition of Fe powder and Ni powder is beneficial to the transition from amorphous carbon to crystalline carbon,and the increase of heat treatment temperature is beneficial to the formation of crystalline carbon and spinel. Carbon nanotubes and high temperature ceramic MgAl2O4 whisker were obtained when the heat treatment temperature was higher than 1 200 ℃,which is helpful to improve the mechanical properties and thermal shock resistance of low carbon MgO-C refractories.

Using tabular corundum as main raw material and calcium aluminate cement as binder，the effects of four kinds of alumina powder on the properties of corundum based castable were studied.The results firstly show that with the particle size multi-peak distribution,alumina powder CTC-55 can fully filling the gaps between aggregates,aggregates and fine powder,and the fluidity of the castable with the same amount of water is better than the other three;secondly the castable with alumina powder CTC-55 has higher strength after sintered at the temperature of 1 500 ℃,because the CTC-55 has better filling ability,which can reduce the porosity of castable,promote sintering and improve the dryer and sintered strength.

By using the super-excellent bauxite,fused magnesia and magnesium-carbon recycled materials as aggregate and fused corundum,fused magnesia and other carbides as matrix,it is important to study the properties of micropowder and magnesium-carbon recycled materials on the wall repair of carbon-containing ladle,especially the effect of the adhesion properties.In the experiment,the residence time of the appropriate amount of mud mixed with water and thrown into the vertical tile surface with a small shovel was used as the basis for judging the adhesion.As a result,7% α-Al2O3 powder,4% silica fume and 25% magnesium-carbon recycled material are better.

In this paper,the characteristics of cold and hot pneumatic conveying of limestone powder are studied by means of orthogonal experiment.It is determined that the pressure of the silo top is the most influential factor for pneumatic conveying of limestone powder.At the same time,the influence of the temperatures of flash calciner and cyclone separator on the activity of limestone powder calcined products are investigated.It is found that the activity of limestone powder calcined products significantly improved  with the increase of cyclone separator temperature.

With the main raw materials of high quality bauxite,corundum,fused magnesia and alumina magnesia spinel,adding a proper amount of additives the performance of ladle repair material can be improved by adjusting the particle size distribution and composition.The improved repair material has been used in  a 300 t ladle of a steel plant,which is proved to have good plasticity and adhesiveness; excellent construction and performance; less rebound and adhesion rate is more than 95%;after being applied once and used for one cycle (30~35 furnaces),the repair material on the east and west sides of the ladle still exist.

In order to reduce the production cost of refractories,the types of slide plates are extended from oil-immersed,nitrided and fired ones to unfired and unimmersed ones.Without high temperature treatment,the molding of the unfired and unimmersed slide plate has high requirement for  the mud service behaviors,which has big impact on slide plate appearance and application effects.

Ladle upper slide gate is a kind of precast refractory brick which is often replaced.During hot-state replacement process,the slide gate is dismantled by manual crushing with a pneumatic pick,which has the dis advantages of high labor intensity and low safety factor.Our company develops a ladle slide gate drawing mechanism for hot-state replacement,greatly improves the work efficiency.

The sleeve diversion lime kiln has the advantages of high practicability,gas burning and coal burning.It is small investment,quick effect,suitable for calcining small particle size raw materials,and good prospects for comprehensive utilization.

This paper introduced the specific items,reference standards and methods of limestone pre-production inspection and testing,interpreted the various indicators of limestone pre-production inspection and testing,introduced the cases of limestone inspection and testing of three companies,analyzed and summarized the effect of limestone pre-production inspection and testing on lime production.

The effect of the addition of borax on the properties of magnesia-forsterite dry mix was studied by using lightly burned forsterite,sintered magnesia and fused magnesia as raw materials and phenol formaldehyde resin as binder.The results show that borax has little effect on the bulk density of the sample,the strength at room temperature and after burning increases with the addition of borax,and borax can improve the slag resistance of dry materials,but too much of it will have the opposite effect.

The project of environmental protection reconstruction for ultra-low emission of flue gas from active lime rotary kiln adopts the technology of desulfurization with baking soda powder.The baking soda powder (NaHCO3) is decomposed into sodium carbonate (Na2CO3) in flue gas.Because Na2CO3 is very active, it will react with acid substance in flue gas to remove SO2 and other acid substance. After the project was put into operation, the SO2 emission was nearly zero.