Reasearch And Development Of Stainless Steel Slag Fertilizer

Stainless steel slag was a by-product of steel metallurgical industry and a kind of industrial solid waste of high emissions. It not only occupied the farmland, but also put great pressure to environmental management. In recent years, the national policies included circular economy and construction of conservation-oriented society demanded comprehensive utilization of Stainless steel slag. After pre-treatment, the heavy metal content of steel tailings had been reduced to trace amount. Moreover, stainless steel slag contained a large number of useful elements which were beneficial to soil and crops, such as calcium, magnesium, silicon and low amounts of manganese, zinc, copper, and had characteristics of porosity, large specific surface area and good absorption performance. Thus, it is feasible to apply stainless steel slag to agriculture.In this paper, a series of experiments were conducted about stainless steel slag:① The effects of stainless steel slag on crops yield were studied with plot experient, monitoring the environmental safety risks of stainless steel slag. ②The stainless steel tailing fertilizer was producted through developing formulas and granulation process, and its sustained release properties were studied to solve the problem of alkaline and dust existed in the application process and to provide technical support for the industrial production of the stainless steel slag fertilizer.The results of this paper were summarized as follows:1. The amount of stainless steel slag (37.5 kg/hm2) was contributed to promote corn yield, and stainless steel slag with organic manure was a good formula of stainless steel slag fertilizer. Stainless steel slag could increase soil pH to some degrees, and had no significant effect on CEC and soil organic matter. Stainless steel slag had no cumulative environmental safety risks to soil and corn.2. The optimal condition of binder production:the content of H2O2 was 3% of the starch content, the NaOH was 5%, and oxidation time was 60 min. Biological toxicity test showed that the optimum binder content was about 1% in the granulating. Storage test showed that the properties of adhesive was stabilized after 3 days and remained the same in two weeks which could apply to industy.3. Formulation study revealed that there were two available formulation (stainless steel slag:distiller’s grains:urea was 1:5:4 and stainless steel slag:distiller’s grains: ammonium was 1:4:5, respectively). The two fertilizers satisfied with fertilizer standards through measurements. Slow-release test showed that, compared with powder fertilizers, the two partical fertilizers had obvious slow-release effect on nitrogen, phosphorus, potassium, calcium and silicon.