JPH0128818B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for treating various types of furnace slag produced in iron and steel manufacturing processes, and more specifically, a furnace slag treatment that can efficiently recover iron and steelmaking concentrates with high iron content. Regarding the method.

Most of the blast furnace slag, converter slag, electric furnace slag, etc. generated in the iron and steel manufacturing processes were disposed of by dumping, but in recent years, from the perspective of reducing landfill sites and making effective use of resources, efforts have been made to recover iron in furnace slag and mine slag. is used as aggregate.

In the process of crushing furnace slag, the iron content is recovered as concentrate for iron and steel making using magnetism. Also, efforts have been made to grind the ore using an autogenous grinding mill. Examples of these prior art techniques include Japanese Patent Publication No. 51-33047, Japanese Patent Application Publication No. 147416/1972, Japanese Patent Application Publication No. 151615/1973,
Some are described in various publications such as No. 52-33163. By the way, the contents of these prior art examples are summarized as follows: (1) The maximum dimension of the furnace slag to be treated is usually 300 mm, and even in special cases it is 500 mm or less.

(2) Furnace slag with a size of 300 mm or less and a high iron content of 50 to 60% is usually converted into concentrate as is, or polished with a rod mill or autogenous grinding mill to increase the iron content to 90% or more. It is made into concentrate.

(3) Furnace slag with a size of 300 mm or less and a low iron content is crushed, magnetically sorted, and sieved, and either converted into concentrate as it is, or polished with a rod mill or autogenous grinding mill to reduce the iron content. It is made into concentrate by increasing the amount even more.

(4) Furnace slag with a size of 500 mm or more is sorted using a lifting magnet or visually, and only the furnace slag with a low iron content is crushed to a size of 300 mm or less, and various treatments are carried out.

(5) Furnace slag with a size of 300 mm or more and a high iron content is
There are many unprocessed items that have been piled up, and the processing is outsourced to specialized companies using the following method.

(b) Dropping a weight of about 2 to 5 tons.

(b) Gas cutting.

(c) Drill a hole and treat with dynamite.

(d) Drill multiple holes in a cross pattern and drive steel rods into them.

Therefore, the treatment of bulk furnace slag with a size of 300 mm or more and high iron content by a specialized contractor is an inefficient work that requires human labor, and is also a work with a high risk of scattering of furnace slag and iron pieces. It was hot.

For this reason, there has been a long-awaited development of a method for efficiently processing the above-mentioned lumpy slag and recovering it as concentrate for iron and steel manufacturing.

Therefore, in order to find a method for efficiently processing the above-mentioned lumpy slag, the present inventors conducted a test in which three-point bending stress was applied to slag with a size of 500 mm or more and a high iron content. I got good results.

(1) In the case of pig iron, the pig iron itself and the slag involved were roughly divided into two or more large lumps and fine slag until the iron content was close to 100%. At this time, the size of the slag attached to or entrapped in the pig iron was distributed on the smaller side compared to the size of the coarsely chopped pig iron.

(2) When the iron component is steel, the steel bends into a dogleg shape, causing the furnace slag attached to or entrapped in the steel to separate, and also to damage the thin parts of the steel itself, surface irregularities, and internal parts. From a defective part like a nest 2
Roughly chopped into three or more large chunks.

(3) The iron content of the furnace slag that was roughly cracked and transformed in items (1) and (2) above always increased, and in some cases exceeded 90%.

It is generally thought that it is impossible to roughly divide the metal in the furnace slag into two or more large lumps, but its properties are not homogeneous like steel plates, cast steel, and cast iron, and the surface It has many irregularities and sharp cracks, and contains many shrinkage cavities and blowholes, which are often referred to as casting defects. Therefore, if three-point bending stress is applied to the metal in the furnace slag as in the above test, stress concentration will occur on the surface and internal defects of the metal, and the stress will be higher than the compressive strength inherent to the iron content. , it will be roughly split into two or more large lumps and fine slag with a fraction of the compression force, and because the slag is involved in the metal, the ratio of slag to the rough cracked section will be It is recognized that the larger the number, the more roughly the force will be required to break it.

The present invention has been made with this point in mind.
It is an object of the present invention to provide a furnace slag treatment method that can efficiently recover concentrate for iron and steel manufacturing with a high iron content.

The furnace slag processing method of the present invention will be explained below based on the drawings. The figure shows the processing process for furnace slag. First, the bulk furnace slag with a size of 300 to 500 mm or more, such as blast furnace slag, converter slag, and electric furnace slag generated in the iron and steel manufacturing process, is used as a raw material. This is processed into a magnetic separator. Magnetic separation is performed to separate lumpy furnace slag with a high iron content of 50 to 60% or more and iron content of 50% or more.
Separate into low lumpy slag ~60% or less. Next, the lumpy slag with a high iron content of 50 to 60% is placed in a rough splitter, and three-point bending stress is applied to roughly split or fold it into two or more large lumps and fine slag. The slag is separated by deformation and peeling to reduce the size to 300-500 mm or less, and a part of the slag is peeled off to increase the iron content. The above-mentioned lumpy slag with a low iron content of 50 to 60% or less is finely processed using a compression crusher (oscillating crusher) similar to the conventional rock treatment.

The furnace slag, which has been reduced in size through the rough cracking or deformation and has an increased iron content, is then magnetically sorted using a magnetic separator to separate furnace slag with a high iron content of 50 to 60% or more and iron content. The furnace slag with a low iron content of 50 to 60% is separated into slag with a low iron content of 50 to 60%.
Among furnace slag with a high iron content of 60% or more, slag with a high iron content of 90% or more is recovered as concentrate for iron and steel manufacturing.
Furnace slag with a content of 90% or less is subjected to polishing treatment, and the polished ore product is sieved and sorted using a vibrating sieve with a mesh size of 40 mm, and the polished ore with an iron content of 90% or more on the sieve is used as concentrate for iron and steel manufacturing. Collected as

The slag that falls under the sieve has an extremely low iron content, so it is discarded.

Thus, the iron content is 50 for dimensions over 300-500 mm.
~60% lump slag can be continuously and efficiently 300~500
The dimensions are as follows, and the iron content is increased to over 90%, which will be recovered as concentrate for iron and steel manufacturing.

In fact, 100 tons of block slag from a blast furnace with a size of 400 mm or more and an iron content of 50 to 60% was processed using the furnace slag treatment method of the present invention, and the result was that steel with a size of 250 mm or less and an iron content of 90% or more was processed. - Concentrate for steelmaking could be efficiently recovered, and the time required for this was 4 hours, and the process was extremely efficient and workability was good.

However, with the conventional method of treating furnace slag by dropping a weight, iron content of 50 to
It took 50 hours to process 100 tons of lumpy slag from a 60% blast furnace, which was extremely inefficient and was highly dangerous due to the scattering of slag and iron pieces. It was hot.

As can be seen from the above explanation, according to the furnace slag treatment method of the present invention, the iron content is 50% when the size is 300 to 500 mm or more.
High-grade concentrate for iron and steelmaking with an iron content of 90% or more can be continuously and extremely efficiently recovered from ~60% lump slag. Further, the treatment of the lumped furnace slag can be carried out extremely efficiently in a short period of time, and since the furnace slag and iron pieces are not scattered, there are effects such as safer work.

[Brief explanation of drawings]

The figure is a flow sheet of the furnace slag treatment method of the present invention.

Claims (1)

[Claims] 1. In the treatment method for various types of furnace slag produced in the iron and steel manufacturing processes, the bulk furnace slag is magnetically separated into furnace slag with a high iron content and furnace slag with a low iron content, and then the iron content is A three-point bending stress is applied to the furnace slag with a high degree of roughness, and the size of the furnace slag is reduced by roughly cracking two or more large lumps and fine-grained furnace slag, or causing separation of the furnace slag by folding deformation and peeling in a dogleg shape. In addition, the furnace slag is stripped to increase the iron content, and then the furnace slag with the increased iron content is magnetically sorted to separate the furnace slag with a high iron content and the furnace slag with a low iron content. A furnace slag treatment method characterized by grinding furnace slag with a high iron content, sorting the polished ore product through a sieve, and recovering the polished ore on the sieve as a concentrate for iron and steel manufacturing.