In the mining industry, SAG mills are an important type of grinding equipment, and their core components, SAG mill linings, are attracting much attention.
SAG mill linings, seemingly just a layer of protection for the mill cylinder, play a vital role. It is like a loyal guard, protecting the mill cylinder from direct impact of grinding balls and materials, while also taking on the heavy responsibility of lifting grinding balls and materials, as well as grinding and crushing materials with them. With the widespread application of SAG mills in the mining industry, especially the increasing number of large SAG mills, linings are facing unprecedented challenges.
According to statistics, the annual consumption of steel wear-resistant castings in China is more than 3.5 million tons, and demand is still growing. This reflects the broad prospects of the wear-resistant materials industry and highlights the important position of linings in the entire wear-resistant materials industry. At present, the service life of SAG mill linings has always been a problem. In large domestic SAG mills, the service life of the linings is usually no more than 4 months. This short life brings many inconveniences and increased costs. For example, frequent replacement of liners not only reduces the operating efficiency of the mill, but also increases the maintenance cost of the mill.
From the perspective of influencing factors, the first is the type and specification of the semi-autogenous mill. The working principles of different types of semi-autogenous mills are different. For example, although the grinding methods of autogenous mills, semi-autogenous mills and ball mills are basically the same, the failure forms and service life of the liners are different. When the semi-autogenous mill is working, in addition to the effect of the material itself, the added grinding balls will produce a huge impact force on the liner during the falling process, especially in the case of high ball load and low filling rate. This impact force is more obvious, making the failure form of the liner mainly fracture and wear, and the service life is short.
The operating conditions of the mill also have a significant impact on the life of the liner. During the trial operation, due to the instability of process parameters, fluctuations in feed volume, uncertain grinding ball addition, and repeated restarts after shutdown and maintenance, the liner is prone to huge impact and the risk of fracture is greatly increased. In normal operation, factors such as mill speed and material filling rate should not be underestimated. If the speed is too high, the impact of the grinding balls and materials will be enhanced, and the liner will be severely impacted and worn or even broken; if the material filling rate is unreasonable, whether it is too high or too low, it will affect the working stability of the mill and have an adverse effect on the life of the liner.
In addition, the hardness, size and filling rate of the grinding balls will also affect the life of the liner. The hardness of the grinding balls is related to the wear resistance of the liner. The service life of the liner may be reduced as the hardness of the steel balls increases; the larger the size of the grinding balls, the greater the impact on the liner. At the same time, the structure and material of the semi-autogenous mill liner are also critical.
In order to improve the service life of the semi-autogenous mill liner and the overall performance of the semi-autogenous mill, the industry has been exploring. Some successful cases of increasing production and efficiency provide ideas for solving the problem. For example, in actual cases, by adding gravel removal plates, increasing the filling rate of steel balls, rationally matching ore, optimizing the liner structure and a series of other measures, the production capacity of the semi-autogenous mill has been improved, and the service life of the liner may also be indirectly extended.
In terms of research and development, relevant personnel are also working hard. A large-scale semi-autogenous mill barrel liner and preparation method came into being. Through specific material formula, such as the use of medium-high carbon CrNiMo steel and resin sand, combined with appropriate pouring and riser systems and heat treatment processes, the wear resistance of the liner is improved while ensuring its toughness, so that the service life of the liner in large semi-autogenous mills reaches 4.5 months.
In short, under the background of mining development, the performance and life issues of semi-autogenous mill liner need to be solved urgently. Only by comprehensively considering various factors and through continuous technological innovation and practical exploration can the semi-autogenous mill liner play a better role and promote the efficient and stable development of mining production.