This paper compares the properties of magnesia-dolomite system refractories with different contents of CaO.It is concluded that with the increase of CaO content in samples,the hydration resistance reduces gradually,when the CaO content is below 20%,the samples have good hydration resistance,when the CaO content reaches 56.9%,the hydration resistance drops evidently,and the samples will not be used any more.

Rational design for tundish retaining wall was used to optimize tundish flow field,uniform tundish temperatures, accelerate accumulation and floatation of the inclusion,and improve cleanliness of molten steel in tundish.

This paper introduced an automatic venting device for molding of shaped products.The device for improved the quality of the exhaust gas in molding process and efficiently eliminated the layer cracks,ultimately guarated the product quality and increased the production efficiency as well as reduced the production cost.

The ringing period of gas-burning lime rotary kiln is about half a year，this paper analyzed the causes of ringing formation to reduce cost and improve product quality.The reasons of ringing were as follows，firstly inclusions in coke oven gas and converter gas probably contained some chemical compositions which could form low melting point oxides with CaO，secondly raw materials contained clay，thirdly feeding rate was improper.For the reasons above，some solving methods were put forward，such as strengthening inspection and management of raw materials，treating fuel gas before use and optimizing operation process and so and.

According to the requirements of control process of environmental desulfurized limestone powder processing system, the automation control of milling system is realized by using S7-300, Profibu-DP bus communication, frequency control and remote video monitoring technology, and increases the accuracy of materials charging,powder selecting and qualified rate of limestone powder.

Double hearth lime kiln with its low heat consumption,the characteristics of high lime quality is widely used in the metallurgy industry and domestic,but in the long\|term production,double hearth lime kiln waste gas has been letted out, the temperature of the waste gas is low, and did not arouse enough attention, then has not been recycled.This paper focus on this part of the heat recycling.

It is difficult to treat the blockage of coal injection pipe and nozzle,which consumes huge labour power and material resources and seriously affect the stable operation.Therefore,it is necessary to look for a simple treatment in stable operation of the beam lime kiln.