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Steel surface pretreatment is a very important process. The surface pretreatment of steel for production in our factory was originally desulfurized and descaled with sulfuric acid solution, and passivated with sodium nitrite solution. Due to high cost and poor pretreatment quality, it was decided to reform the pretreatment process. We conducted trials and economic comparisons on several methods, and finally adopted a new steel rust removal passivation process that was promoted by the National Seventh Five-Year Plan. With this new process, the descaling solution can be used for a long time, and only the loss can be added, so that the cost is greatly reduced and the pollution is reduced. Since September 1987, this new process has been applied to the pretreatment of steel in our factory. The quality of derusting is relatively stable and the effect is ideal.