This paper summarizes the current requirements for ultra-low emission in the steel industry and the future policy orientation in China,and highlights the ultra-low emission technology applied by the ZT 5000 lime project according to the environmental protection requirements,which is of reference significance for the same type of enterprises.

Micron and submicron SiC powders were used as matrix for preparation of new type direct bond SiC refractories.The effects of different particle size distribution on the bulk density apparent porosity and linear shrinkage of pressureless sintered samples at 2 100 ℃ were investigated.The experimental results show that after sintering at 2100 ℃,the linear shrinkage increases with the increase of SiC  powder.When the matrix is pure submicron SiC powder,the sintering activity of the sample is better than that of the sample with micron SiC powder and the sample with micron-submicron mixed SiC powder.

By optimizing and improving the refractory materials of the lining and vulnerable parts of traditional Maerz kiln,the local repairing method of the lining is adopted,which reduces the maintenance cost and prolongs the service life.

The effects of La2O3 on the structure and properties of periclase-forsterite refractories were studied with fused magnesia and silica powder as main raw materials.The results showed that the introduction of La2O3 and their increase in content produce irregular,rod-shaped and needle-shaped lanthanum containing silicate phases between the main crystalline grains; The in-situ formation of the phases was conductive to improve the bulk density and decrease the apparent porosity of the materials,the mechanical properties and thermal shock resistance were also significantly enhanced；The enhanced microstructure from the in-situ formed lanthanum containing silicate phases elevated the penetration resistance of the materials to the melted glass batch and sodium sulfate.

Cordierite (Mg2Al4Si5O18) ceramics are widely used in the fields of structural ceramics, catalyst carriers,honeycomb ceramics and electronic materials owing to its excellent mechanical properties,low dielectric constant and low thermal expansion coefficient.In recent years,researchers have made significant progress in cordierite crystal structure and improving the density.In this paper,state-of-the-art research status of cordierite ceramics are reviewed including the crystal structure and densification of cordierite ceramics.On this basis,the issues in the preparation and application of cordierite ceramics are pointed out and the development trend of dense cordierite ceramics is prospected.

Continuous casting intelligent manufacturing requires thinning the thickness of the tundish cover and increasing the baking hole.In order to solve the problems such as the overall strength of the steel structure,high temperature deformation and poor heat insulation performance,the modification design of the steel structure for tundish cover was optimized.After the on-site verification,the service life of the cover is increased from 42 days to 85 days,and the surface temperature of the cover is reduced by about 180 ℃.

The residual bricks of slag line bricks after smelting low-carbon steel in the electric furnace workshop of a steel plant were selected to study the corrosion mechanism of slag line bricks by low-carbon steel by scanning tunnel electron microscope (SEM) and energy spectrometer (EDS).The results show that the carbon in the slag line brick is oxidized by FeO in the slag and O2 in the environment,and the reduction reaction of MgO and C at high temperature causes the removal of carbon and the formation of a decarburization layer,resulting in the loose structure of the slag line brick;With the formation of the decarburization layer,the slag penetrates into the decarburization layer through the loose matrix,the calcium silicate phase in the slag erodes the periclase grain boundary to form low melting point C2MS3,and the slag line brick is oxidized,decarburized and eroded repeatedly.

Nickel-iron slag is a kind of solid waste that was produced during the smelting process of nickel-iron alloys.At present,most of the nickel-iron slag has been not utilized effectively,they are accumulated in large quantities and seriously polluted environment.The current comprehensive utilization of nickel-iron slag in the preparation of concrete,cement,cementitious materials,mineral wool,glass-ceramics and valuable metal recycling are summarized,and several suggestions are put forward.

Many large and medium-sized converters in domestic steel plants began to adopt sliding gate slag-blocking tapping technology.The supporting tap hole bricks have become one of the factors affecting the development of the sliding gate slag-blocking technology.In this paper,the application of the sliding gate slag-blocking tap hole brick is analyszed,the damage reason is studied and the improvement measures are  put forward.The improved and developed long-life tap hole brick has a good application effects.

A large amount of coal or gas with high calorie value is used for the production of lime in rotary kilns.Coal,coke oven gas or natural gas are mixed fired with blast furnace gas in some production lines.At the same time,blast furnace gas and converter gas are low calorie value gas fuels for iron-making process,and the steel industry has been looking for ways to improve the utilization rate of them.In this paper,the utilization status of low calorie value gas in lime rotary kiln is analyzed,and a new utilization method is introduced.

The basic structure and production state of the vertical preheater are introduced, and the influencing factors of resistance are analyzed.The numerical deviation between the calculation results obtained by using Eugen’s formula and the actual production is small,which can meet the needs of engineering design and provide a reference for the development,design and structural optimization of the vertical preheater.

Refractory automation production equipment in China has experienced from scratch,from weak to strong development process,from the initial simple manual tools updated,gradually developed into intelligent warehouse,automatic ingredients equipment,“four-in-one” molding equipment,automatic packaging equipment such as automatic equipment.With the further application of computer software system,refractory has moved into the  industrial 3.0 era.Taking the intelligent transformation and upgrading of the company as an example,this paper simply describes the effects and problems of green and intelligent refractory production equipment,puts forward the problems faced by the green and intelligent development of refractory production equipment in China,and looks forward to the future development prospects.

The measurement conditions for determining the chemical activity of light calcined magnesia by citric acid reaction time method and hydration method were studied，and the optimum measurement conditions for determining the chemical activity of light calcined magnesia by the two methods were determined.The test data were used as the revision basis of YB/T 4019-2020 “Determination of chemical activity of light calcined magnesia”.