Briquette as material for steel making and method for production thereof

Abstract

Cotton-like aggregates (B) containing grinding chips from an iron-based metal and a grinding fluid containing oil and water are compression molded thereby forming a brittle compact (C) in which the fibrous grinding chips are roughly sheared and which is removed of excessive water and oil. The brittle compact (C) is crushed for further finely shearing the grinding chips and then, the resultant grinding chips are mixed with a solidification assistant (D) for obtaining powder (E) containing the solidification assistant (D). The powder (E) is solidified by compression molding, thereby forming a water-containing briquette (F). A briquette (A) for use as steelmaking material, which contains powdery pure iron and oil, is obtained by removing the water from the water-containing briquette (F). Without crushing the brittle compact (C), it is also possible to form the briquette (A) for use as steelmaking material by impregnating the brittle compact (C) with the solidification assistant (D) and then drying th compact.

Description

Technical Field[0001] The present invention relates to a briquette for use as steelmaking material and a method for forming the same and more particularly to a technique for effectively utilizing grinding chips from an iron-based metal.BACKGROUND ARTS[0002] Grinding chips which occur in the machining of an iron-based metal such as bearing steel, carburized steel and the like (hereinafter, the term "machining" will be used to represent a concept also including grinding, super-finishing grinding, lapping and the like) are recovered in the form of cotton-like (fibrous) aggregates including a grinding fluid containing water and oil, abrasive grains, and the like. Since the cotton-like aggregates contain a considerable quantity of pure iron, there have been made attempts to reuse the aggregates as steelmaking material. Unfortunately, however, the cotton-like aggregates contain such a large quantity of water that bumping (phreatic explosion) will be caused by the water if the aggregates a...

AI Technical Summary

Benefits of technology

[0011] The so-formed briquette for use as steelmaking material is a dry solid mass and hence, the briquette is unlikely to cause bumping or to be scatteringly carried upward if it is directly charged into a blast furnace. In addition, the handlings, such as transportation, storage and the like, of the briquette are easy. Since the briquette contains oil, the oxidization of the powdery pure iron is suppressed. Therefore, the briquette can be reused as a high-quality steelmaking material, thus contributing to the environmental conservation as well as to the reduction of disposal cost of the grinding chips.

[0034] In all of the aforementioned methods for forming the briquette for use as steelmaking material, a material containing not less than 0.2 wt % of carbon may be employed as the grinding chips (claim 25). In the case of cotton-like aggregates containing the grinding chips having such a great springback, as well, the cotton-like aggregates can be rigidly solidified while eliminating the influence of the springback.

Problems solved by technology

Unfortunately, however, the cotton-like aggregates contain such a large quantity of water that bumping (phreatic explosion) will be caused by the water if the aggregates are directly charged into a blast furnace.

The use of a reducing agent results in increased costs.

On the other hand, the grinding chips with the oil adhered thereto are prone to adhered to each other.

Hence, the compression molding of the cotton-like aggregates involves difficulty about accomplishing solidification to a desired strength.

Furthermore, in the case of cotton-like aggregates containing a large quantity of grinding chips from an iron-based metal containing not less than 0.2 wt % of carbon, the aggregates present such a great springback when compressed that it is difficult to accomplish the solidification to a desired strength by compression molding the aggregates.

In addition, the fibrous grinding chips contained in the cotton-like aggregates are hard to crush by means of a hammer mill or the like and hence, the cotton-like aggregates cannot be sheared finely.

This leads to a difficulty of processing the cotton-like aggregates into briquettes or the like.

Unfortunately, if such recovery dusts are directly charged into the blast furnace, the dusts are scatteringly carried upward to be collected by the dust collector again.

However, the landfill disposal is not desirable from the standpoint of the effective utilization of resources.

Furthermore, the landfill disposal entails the environmental deterioration as well as the increase of the disposal cost.

The recovery dusts, in particular, requires an even greater disposal cost because the dusts contain heavy metals and must be committed to the landfill disposal as special industrial wastes.

Hence, the briquette is unlikely to cause bumping or to be scatteringly carried upward if it is directly charged into the blast furnace.

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