Wear resistant grinding rods

一、Introduction to Steel Bar of Rod Mill

Bar mill is widely used in coal slurry preparation, bauxite, tin - tungsten ore primary grinding, quartz sand, silica sand, sand aeration, steel slag, potassium albite, coal methanol and other industries for its advantages of energy saving, high efficiency, even grinding and no grinding. Steel rod for bar mill refers to the grinding medium rod is used in various bar mills. Like ball mill, it needs to have higher wear resistance, especially hardness and impact value, in order to ensure lower wear rate and lower broken rod rate. In response to the above needs, relying on years of experience in production and research of ball mill grinding balls, the company set up research and development team to tackle key research issues. Starting from raw materials, after years of exploration, experiment and practice, in recent years, the company has developed a new type of wear - resistant rod (including raw materials, heat treatment and tempering process, production patented equipment). At present, the new bar mill steel bar has been exported to more than ten countries; domestic customers are all over the provinces; customers generally feedback with "polishing bar" than with ordinary round steel comprehensive benefits have been improved. The bar mill is generally of wet overflow type, which can be used as a first - stage open - circuit grinding. The steel bar of bar mill should be chosen as material of large steel mill. At present, the steel bar used in domestic market is rolled by steel mill. Its technical requirement is not high, wear resistance effect is not ideal, consumption is large, and national resources are wasted in a large amount. Round steel is a raw material produced by a steel mill, not a finished product. There will be many problems when it is used as steel rod for bar mill.

二、Problem and Cause Analysis of Common Steel Bar

　1、High abrasion: Round steel consumes more steel rods because of its low hardness and non - wear resistance, which indirectly results in heavy task and high cost of ferromagnetic separation in some industries such as quartz sand and feldspar, and even affects the whiteness of ore powder.

Two ends of steel bar are pointed thin: The two ends of steel bar are pointed thin, which is caused by many reasons. The main reason is that the contact probability and area of the inlet and outlet of the two ends of steel bar of bar mill are larger than the middle part, which results in the grinding strength of both ends being obviously higher than that of the middle part. Once the ratio of the two ends and the middle is obviously different, it needs to be removed in time so as to avoid the parallel operation of steel bar. The trajectory was disrupted.

3、Broken rod: The main reason is that the material is loose inside. Generally, the problem of steel billet in steel works is that only large steel plants can meet the internal tight technical requirements, especially steel rods with diameter of more than 70 mm. Small steel plants have low compression ratio and poor organization because of insufficient power of equipment. In addition, the internal stress of round steel is relieved by cold insulation without pit when it leaves the factory, which is easy to cause stress cracks to lead to bar breakage. The internal stress of round steel used in bar mill must be relieved by heat treatment.

4、Bending rod: The main reason for bending rod is that the hardness of round steel is very low and relatively soft. When it is subjected to external forces such as impact force in the mill, it is easy to bend. Once a rod is bent, the parallel arrangement of the steel rods in the mill will be disrupted (the steel rods run parallel in the mill, and the materials are ground into small particles or powders when they enter the gap between them). In light of this, the mill will be inefficient after the steel rods are disorderly ordered, and in heavy, the steel rods will be thrown out of the mill, threatening the safety of workers and damaging the mill and other production equipment.

　5、Through a lot of experiments, it is proved that when the hardness of the grinding rod is about HRC50, its wear resistance is better and the broken rod rate is the lowest, which is the optimal choice of the grinding rod hardness. At present, the best performance of the product is grinding rod surface hardness HRC50 or so, hardness shows a decreasing trend towards the heart. This can not only take into account the wear resistance of the grinding rod, but also ensure the toughness of the grinding rod and reduce the brittleness of the grinding rod.