JPS5846461B2 - Manufacturing method of cement clinker using converter slag as raw material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a cement tarinker using converter slag as a raw material, and more specifically, to a method for manufacturing a cement tarinker using converter slag as a raw material, and more specifically, a method for manufacturing a cement tarinker using converter slag as a raw material. The present invention relates to a method of manufacturing cement clinker by a wet firing method using a slurry-like phase rich in CaO and SiO2 after magnetic separation and recovery of iron and the like as a raw material.

Due to the seriousness of the problem of converter slag treatment, a great deal of effort has been made in various fields including steel manufacturing companies, but the current situation is that no fundamental solution has yet been found.

The main causes are metal components such as Fe, Mn, and Mg, and Ca.
, 5i02 and other nonmetallic components are difficult to separate.

As a result, the components, which were individually valuable, were not utilized and had to be discarded.

Moreover, free calcium oxide present in the slag,
Due to the collapse phenomenon caused by so-called free lime,
The reality is that it cannot be used as aggregate, and furthermore, because of the highly alkaline liquid that oozes out when it is exposed to rainwater, there are restrictions on its ability to be dumped outdoors or in landfills.

In order to solve this problem, the inventors of the present invention have conducted intensive research on reforming methods for converter slag, and have found a method of injecting pure oxygen, etc. into the slag molten converter slag, or CaO15iO2 (molar ratio) is reduced to about 1.5 to 2.0 by oxidation treatment performed in a solid state and addition of a SiO2-containing substance.
By performing basicity adjustment treatment to adjust the basicity to 5, almost all of the iron and manganese in the slag are concentrated solidly dissolved in a ferromagnetic Ng-Mn ferrite phase, and Ca containing phosphorus etc.
2 of the dicalcium silicate phase consisting of O and SiO2
By suppressing the phase or the degree of oxidation in the above oxidation treatment to a certain degree, it is possible to produce a modified material whose main constituents are the Mg Mn wustite phase, which is non-ferromagnetic but contains some iron, etc. in addition to the above two phases. Developed a method to obtain converter slag,
We established a system for efficiently recovering and reusing high-quality iron resources by subjecting the obtained reforming converter slag to a simple method called magnetic separation (%Global Application No. 51-043341).

By the way, the Fe-, Mn-, and Mg-rich phase that constitutes the reforming converter slag produced by the above method and the CaO1SiO
The size of each of the two rich phases is on the order of several tens of microns, so in order to efficiently separate and recover iron, etc. by magnetic separation, it is necessary to grind the solidified slag quite finely. Therefore, magnetic separation treatment of such fine particles is necessary. The wet method will be applied.

When this wet magnetic separation is performed, each phase obtained becomes a slurry, and the Fe, Mg, and Mn rich phases are recovered as concentrate and reused as an iron source.

On the other hand, the CaO, 5i02') Tsuchi phase remains as tailings.

The purpose of the present invention is to establish a method for effectively utilizing the slurry-like CaO2SiO2 rich phase recovered as the tailings, and, in combination with the reforming treatment method proposed by the present inventors, to provide an innovative solution to the problem of converter slag. It is intended to provide a countermeasure.

When attempting to effectively utilize this CaO, 5i02'J Tsuchi phase, it is considered most advantageous to use it as a cement raw material, considering its component composition and quantity.

However, the current mainstream manufacturing method in the cement industry in Japan is the dry method (suspension or new suspension method), whereas the tailings obtained from the reforming converter slag is slurry, so this method cannot be used. To apply this method, complicated pretreatments such as dehydration and drying are required.

However, since the true specific gravity of tailings is lower than that of concentrate, it is disadvantageous vertically to dehydrate tailings, and it is not advisable to apply it to the dry production method described above.

As a result of various studies, the inventors of the present invention have found that by adopting a wet firing method for firing slurry as the firing method, the series of steps of wet magnetic separation and firing of reformed converter slag can be carried out efficiently. slurry-like Ca
b. We have established a method for effectively utilizing the 5in2 rich phase as a raw material for cement tarinker.

The method of the present invention will be explained below.

The reforming treatment of converter slag is carried out by subjecting the discharged molten converter slag to oxidation treatment and basicity adjustment treatment.

The oxidation treatment can be carried out by, for example, inhaling oxygen gas into the molten converter slag, but in addition, any oxygen-containing substance that can oxidize the molten converter slag, such as gas,
Any solid may be used.

The amount used depends on the utilization efficiency, but when oxygen gas is blown, for example, about 10 Nrn:/7 lag ton or more is blown.

Further, this oxidation treatment can be carried out during or after solidification of the slag that has been subjected to basicity adjustment treatment.

For example, a method of scattering molten slag in the air (
There is a method in which the solidified slag is kept or reheated at a high temperature (400 to 1000'C) and treated in an oxidizing atmosphere.

The degree of oxidation of the slag by the above-mentioned oxidation treatment may be complete oxidation, in which almost all of the divalent iron in the slag is oxidized to trivalent iron, or a part, preferably all, of the divalent iron. Incomplete oxidation may be used such that the ratio of divalent iron to the amount of iron is approximately 50% (by weight) or less.

The basicity adjustment treatment is performed using a SiO2 imparting substance, that is, SiO
This is done by adding a substance containing S 2 or a substance that can be added to the slag to produce S 102.

Examples of the former include silica sand, blast furnace slag, and waxite; examples of the latter include alloys such as Si-Mn and Fe-8i, and ferroalloys.

The basicity is CaO15iO2 (molar ratio) of about 1.5 to 2.
5, preferably in the range of about 1.7 to 2.3.

As a result of the above-mentioned oxidation treatment and basicity adjustment treatment, converter slag contains a ferromagnetic Mg-Mn ferrite phase in which almost all of the iron in the slag is concentrated and dissolved, and phosphorus, etc.
A reformed converter slag is obtained which consists of a mineral phase whose main constituents are a dicalcium silicate phase consisting of ab and 5in2.

Note that if the oxidation treatment is limited to the incomplete oxidation, the above 2.
In addition to the Mg-Mn ferrite phase, a non-ferromagnetic Mg-Mn ferrite phase is generated.
It exhibits a mineral phase consisting mainly of these three phases.

After the oxidation treatment and basicity adjustment treatment, it may be cooled and solidified according to the usual procedure.

In addition, during cooling, the molten converter slag may be made to flow in a high water flow to form converter slag.

The resulting reforming converter slag is pulverized and then subjected to wet magnetic separation treatment.

There are no special regulations regarding the particle size of slag subjected to the same treatment, but
In order to increase the efficiency of magnetic separation, it is desirable to finely grind the slag to a particle size that corresponds to the grain size of each mineral phase that constitutes the slag, for example, to a particle size that can pass 90 or more pieces of rice through a 200-mesh sieve.

The pulverized slag is slurried with water and subjected to wet magnetic separation treatment.

Fine powder of a ferromagnetic Mg-Mn ferrite phase containing iron and the like is recovered as a concentrate, and fine powder of a dicalcium silicate phase consisting of CaO and 5i02 is recovered as a tailings.

The amount of tailings recovered is, for example, about 25 to 35% by weight, and the slurry composition is, for example, Ca056%.
, S io 230, etc.

Then, an appropriate amount of blast furnace slag limestone pulverized into a suitable mesh is mixed into the recovered slurry.

The particle size of the blast furnace slag and the like to be mixed is adjusted to such a degree that it can pass through a 200 mesh sieve of 90 mm or more, for example.

In addition, these mixing ratios are dry weight ratios, even if *
Tailings 30-401 Blast furnace slag 15-30. Limestone 35-4
Adjusted to 5.

The slurry concentration after mixing is, for example, 30 to 30% in water content.
It becomes 40φ (weight).

Cement clinker is obtained by firing the thus mixed slurry in a rotary kiln or the like at, for example, about 1450°C.

Cement is obtained by adding a small amount of gypsum to the obtained clinker and pulverizing it to give a certain specific surface area.

The cement thus obtained has the characteristics required as Portland cement specified in JIS, and can be used as a suitable cement.

Next, the present invention will be specifically explained with reference to Examples.

Example After the completion of the smelting work and the steel tapping work in the converter, 0.00% of silicic anhydride (Sin2) was added from above to the molten converter slag remaining in the converter.
The converter slag was reformed by charging 1037 kg/kg of slag and then using a lance to inject converter oxygen at 0.019 N m7 kg of slag.

Table 1 shows the results of chemical composition analysis of the converter slag before reforming treatment and the converter slag after reforming treatment.

In the same table, (4) is the slag before modification, and (B) is the slag after modification.

After cooling and solidifying the obtained reforming converter slag, it is pulverized to a particle size that allows 90% or more to pass through a 200 mesh sieve, and this is made into a slurry and subjected to wet magnetic separation using a variable magnetic separator. , 28.5% by weight of tailings was recovered.

Its components are shown in Table 2. In the tailings recovered above, a third
Blast furnace slag and limestone having the components shown in the table were prepared in advance for 20
The powder was pulverized to a particle size that allowed 90% or more to pass through a 0-mesh sieve, and thoroughly mixed and stirred to form a slurry with a moisture content of 36φ (weight).

The mixing ratio of the slurry is, in terms of dry weight ratio, tailings 35,
The blast furnace slag was 22.5, and the limestone was 42.5.

This slurry was fired in a rotary kiln at a temperature of 1450°C to produce clinker.

Table 4 shows the components of the clinker obtained.

3.5% (by weight) of natural gypsum was added to this clinker and ground to obtain cement having a particle size of Blaine specific surface area of 3200 i/g.

The thus obtained cement was subjected to various tests in accordance with JIS regulations, and the results shown in Table 5 were obtained.

The table shows the JI specified for Portland cement.
The S standard is also listed.

As is clear from the above measurement results, according to the method of the present invention, a high-quality cement clinker that satisfies all the characteristics required for Portland cement is produced using tailings recovered by wet magnetic separation of reforming converter slag as a raw material. can be manufactured.

As described above, according to the present invention, converter slag, which has traditionally been difficult to process, can be reused as a resource in large quantities, and since blast furnace slag is also used as a source of SiO2, blast furnace slag can also be recycled in large quantities as a resource. can be used.

In addition, by adopting a wet method for cement firing, there is no need to dehydrate and dry the CaO'J Tsuchi phase obtained by wet magnetic separation of reformed converter slag. Cement clinker can be efficiently produced through a series of steps including cement firing using tailings slurry.

Claims (1)

[Claims] 1 Basicity adjustment treatment for converter slag in a molten state to make CaO15iO2 (molar ratio) 1.5 to 2.5 by adding a SiO2-containing substance and oxidation treatment in the molten state, or nuclear basicity adjustment treatment and subsequent Modified converter slag containing MgMn ferrite phase and calcium silicate phase obtained by solidifying slag or oxidation treatment after solidification, or these phases and Mg-Mn wustite phase as main components, is processed into a wet process. A cement tallinker made from converter slag, which is characterized by adding adjustment materials such as blast furnace slag, clay or limestone to the slurry tailings obtained through magnetic separation treatment and firing the mixture in a wet kiln. manufacturing method.