JPS605088A - Slag for use of soil improver - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention is advantageous for the reduction reaction process in the smelting reduction method that uses cheaper energy than the conventional electric furnace method. , relates to slag that can be effectively used as a soil conditioner even after being discharged. Note that the soil conditioner is a type of agent that is sprayed on fields to promote the growth of grain crops.

(Prior art) Conventionally, high chromium alloys, for example aerochrome containing 50% or more of Cr, have been processed in an electric furnace as ``romite ore''.
It has been produced by heating, melting, and reducing the semi-reduced product of 1'7. However, this method has the following problems.

(1) Because expensive electricity is used as reduction energy, manufacturing costs are high, especially in Japan.

(2) The Cr% in the slag discharged outside the furnace is 2 to 5%, and the chromium loss is large. Also, the Cr% in the slag is
The high value of slag limits the range in which slag can be used effectively.

Therefore, we developed the so-called Wr smelting reduction method, which replaces the reduction energy with primary energy that is cheaper than electricity (particularly the heat of combustion of carbonaceous solids such as coal and coke). If it is possible to reduce the number of W children and expand the range of effective use of the generated sura-jime, □ it has great value. However, in order to develop such a process, the following problems must be solved. In other words, in chromium ore, the chromium content is M
Along with gO, At203, etc., sparingly soluble spinel (Mg
O, Fe0) (Cr203.At203) is formed. Furthermore, since the amount of Mgo, At203, etc. in the chromium ore is large, the slag produced is generally viscous or sticky.

Additionally, the amount of slag produced is extremely large. All of these are
In the melt reduction process, the speed of the reduction reaction of chromium oxide by the carbonaceous material and the speed at which fine metal particles generated in the slag settle and separate due to reduction are reduced, and the overall content of the slag (T, Cr%) is reduced. Reduce the rate of decline. This rate can be increased if the temperature can be raised sufficiently, but this is accompanied by the problem of increased damage to the refractories of the reaction vessel. Therefore, as low temperature as possible, large (T, Cr)
It is necessary to find the optimum slag conditions that will allow the rate of reduction to be achieved.

(Objective of the Invention) From the above-mentioned viewpoints, the present invention conducts a detailed experimental study on the smelting and reduction conditions of 2Erochrome, especially the influence of the slag composition, and also examines various methods of utilizing the discharged slag after reduction. This was obtained as a result of the study, and the purpose of this study was to improve the reduction reaction process in the smelting reduction method, which uses energy that is cheaper than the conventional electric furnace method. In addition, it is an object of the present invention to provide a slag that can be effectively used as a soil improvement material even after being discharged.

(Structure, operation, and effects of the invention) The present invention uses chromium ore as the main raw material, adds carbonaceous material and flux, and heats it with blowing acid to reduce and melt and separate the chromium and iron (SiOZ). 1
．． The gist of this article is a slag used as a soil conditioner, which is characterized by satisfying the component condition of 18 (At205 clause At20. = 17 to 22%).

Hereinafter, the present invention will be explained in detail based on specific test results.

FIG. 1 shows an example of equipment used to produce the slag of the present invention. 1 is a rotary kiln used to heat and solid-state reduce pellets formed by mixing chromium ore powder and carbon material powder such as coke (chrome pellets 9 and carbon material 10 in the figure). Reference numeral 2 denotes a converter-like melting reduction furnace which receives the pre-reduced pellets and melts them while proceeding with the reduction of the remaining chromium and iron oxides. The melting reduction furnace 2 is equipped with a tuyere 3 (there may be more than one tuyere) for blowing oxygen-containing gas from the bottom, and a lance 4 for blowing oxygen into the furnace from above. There is. 5 is hood, 61″ is charcoal material,
This is a hopper for flux.

In the melting reduction furnace 2, a gas containing oxygen is introduced into the molten metal from the bottom blowing tuyere 3 (for example, the tuyere is made of a double pipe, and a protective gas such as Pro-Gun or Ar is introduced from the outer pipe. 2 Oxygen is introduced from the inner pipe. supply). This bottom-blowing gas is not only important for strongly stirring the metal 7 and the generated slag layer 8 to promote the reduction reaction of chromium oxide, but also for burning the carbon in the metal and heating the metal bath. , is used to maintain the metal at an appropriate temperature (for example, 920°C or higher and 100°C or lower than the freezing point).

Oxygen supply from top blowing lance 4? #1 is used to generate heat by burning carbonaceous materials such as coke, and is the main source of heat generation in this smelting method.・“In order to achieve the smelting reaction rate, it is important to increase the combustion rate of the carbonaceous material and the heat release rate.To this end, the lance nozzle should be wide-angle, porous (for example, 7 It is desirable to have holes in the furnace so that the coke present in the furnace can be easily penetrated by oxygen jets.

The operating method is as follows.

Approximately % of the metal generated in the previous heat was discharged, and the remaining amount was 1A.
Top and bottom blowing acid is carried out while supplying preheated and prereduced chromium raw material 9 (semi-reduced chromium pellets) from the rotary kiln 1 from the rotary kiln 1 to the melting reduction furnace 2 in the next state. Carbon materials (coal and coke), which are as cheap as possible, are used as reducing agents and exothermic agents.

In order to slag the gangue content in the chrome pellets and the gangue content in the coal or coke, a flux mainly composed of lime, silica stone, etc. is added.

As mentioned above, in the first stage of melt reduction, chromium pellets,
While charging carbonaceous materials and flux, acid is blown with strong stirring to proceed with melting and part of the reduction of the raw materials. ◇After charging a predetermined amount of semi-reduced chromium pellets, the melting and reduction will move to the second stage. do. In the second period, blowing acid was used without supplying semi-reduced chromium pellets.

Continue stirring (replenishing carbon material if necessary). In the second period, unlike in the first period, there is no supply of chromium oxide into the smelting reduction furnace, so the amount of chromium present as oxide in the slag decreases with time.

When (T, Cr%) is reduced to a predetermined value, slag is removed.

Note that slag removal and tapping may be performed at the same time, but if you want to keep the metal weight ratio below a certain value for the operation of the smelting reduction furnace, it is recommended to perform a cycle of tapping 1 (b) for every 2 or more times of slag tapping. It is also possible to do so.

Figure 2 shows (T・Cr%) in the slag in the process described above.
An example of a change in the number is shown below. The first stage is the time when melting reduction is progressed while adding chromium pellets.
, Cr%) are kept at approximately constant values.

On the other hand, in the second stage, the supply of beam pellets is stopped and the content (T, Cr%) present in the slag is reduced. In order to shorten the total time of the first and second stages and increase the productivity of the furnace by operating at the lowest possible temperature, it is necessary to T,Cr
%,) It is important to adopt conditions that cause the dog's rate of decline. In order to investigate the influence of slag components on the rate of decrease of (T-Cr%) in slag, an experiment was conducted using a molten metal of 70 kli using the equipment shown in FIG. A carbon-saturated high-chromium molten metal 36 is obtained in a magnesia-stamped high-frequency induction melting furnace 31, and is stirred by blowing Ar gas into it from a Po2 szorag 34. After inserting the graphite ring 33'ff to prevent the slag reaction, semi-reduced chromium pellets, flux, and coke are added.
Sampling the slag 35 at predetermined intervals,
Changes in the chromium content fi (T, Cr%) of the slag over time were investigated. In the figure, 32 is a high frequency induction coil, and 37 is a lid. (T, Cr%) is the amount of fine particles of (1) chromium oxide existing as a solid, (2) chromium dissolved in the slag, and (3) chromium reduced to metal or carbide. This is the sum of the suspended chromium content (hereinafter referred to as metallic chromium) that cannot be separated by precipitation.

Figure 4 shows (T,
An example of the change in Cr%) over time is shown. Changes in (T, Cr%) in the slag after chromium pellets are added can be apparently divided into a time period that can be summarized using a zero-order reaction equation and a time period that can be summarized using a first-order reaction equation. The period of time that can be summarized by the zero-order reaction equation is the period in which the rate is determined by the process in which the hardly soluble spinel particles contained in the charged chromium pellets are melted into the slag. on the other hand,
-The time period organized by the following reaction equation is rate-determined by the process in which chromium oxide in the molten slag is reduced by carbon.

Time period rate constant: k・ The relationship between the slag component and the slag component is shown in FIGS. 5 and 6, respectively.

In either case, the influence of the slag component was almost the same, and a large value was obtained as a rate constant for AA20. <22
It can be seen that it is necessary to be %.

The reason why such an influence of slag components was obtained is that the rate-determining process of chromium ions in the slag is the rate-determining process in both the zero-order reaction zone and the first-order reaction zone, and its value depends on the viscosity of the slag and the concentration of chromium ions in the slag. This is because it is possible due to the synergistic effect of the diffusion rate constant of chromium ions and the solubility of chromium oxide in the slag. In particular, for At203%, a clear permissible upper limit was found, which is different from the conventional electric furnace method.
In the method targeted by the present invention, the operating temperature is low (1650
℃).

The ability to increase the rate constant ko in the zero-order reaction zone and the first-order reaction zone by 1 means that the (T, Cr4) level in the first period at a certain temperature in Fig. 2 can be lowered and the (T, Cr4) level in the second period can be increased. T
, Cr4), which can lead to lower operating temperatures and improved productivity. In order to obtain a slag composition that satisfies this requirement, At203 in the chromium ore is diluted to 22% or less, and at the same time, CaO and 810□ are added as flux.

These fluxes are charged into the smelting reduction furnace in portions approximately corresponding to the addition of chromium pellets, and the slag components at each point of smelting reduction are changed so as to satisfy the above two conditions.

The molten slag discharged from the smelting reduction furnace is pulverized by spraying with high-pressure water. The slag after water pulverization is pulverized to less than one size, and then metal grains are recovered by magnetic separation.

(T, Cr4)Vi of the slag after separating the metal grains,
The average (T, Cr4) of molten slag is also 0.2 to 0.5
% lower.

FIG. 7 shows the relationship between (T, Cr)% of the powdered slag after water pulverization and magnetic separation and the amount of chromium eluted into the water bath liquid. (T, Cr4
) becomes 0.5% or less, the amount of eluted chromium is below the detection limit and chromium elution does not substantially occur.

FIG. 8 shows that if the soluble silicic acid ratio At203% in the slag is less than 17%, the soluble silicic acid ratio decreases and the effect as a silicic acid fertilizer is reduced, which is not preferable.

Example Rated amount of molten metal (molten metal 1 just before tapping) 50 t top-bottom blowing converter (1 top blowing lance, 7 holes between 7 nozzles, φ x 7 holes, 1 hole in the center, 6 holes on the periphery, 6 holes on the periphery) 25° angle to axis
, 4 bottom blowing tuyeres, a double pipe with an inner pipe diameter of 20 Mφ, and propane flowing through the outer pipe as a protective gas) was used as the reaction vessel,
Intermediate slag drainage was performed once, and 33 tons of molten metal was tapped out at a time.
The plant was operated semi-continuously, leaving 7 tons of hot water.

The main raw material, chromium ore, is mixed with coke powder to form pellets, and the auxiliary raw material, coke, is used as outer coal in the rotary kiln. : Charged and pre-reduced and preheated using the high-temperature exhaust gas emitted from the melting reduction furnace as a heating source. The average composition and temperature of the semi-reduced chromium pellets entering the smelting reduction furnace are as follows. T, Cr, 36'%.

'l', Fe; 18% p chromium reduction rate; 66%
, iron reduction rate i96%, MgO; 10% #A
t203; 10th ratio + 8102; 9%2 temperature 1020℃
. The carbonaceous material is coke (0
Approximately 90% of the lime (88%) goes through the rotary kiln, and approximately 10% of the residue goes through lime (97% Ca0, 20~20~
It was directly charged into a melting reduction furnace together with a 50 mm diameter cylinder.

First reduction stage: Preheated preliminary reduction pellets, coke and lime are charged into the remaining hot water while blowing oxygen-containing gas from top to bottom. The acid blowing speed is top blowing: 1300ONm! '/h
r, bottom blowing 800 Nm x 4 hr. The temperature of the molten metal is measured, and the charging speed of the prereduced pellets is adjusted so that the temperature is controlled between 1580 and 1630°C. Charging of the pellets is completed in about 60 minutes. (T, Cr4) in the slag at this point was 7.6ch.

The lime content was quicklime, and the silica content was silica stone, which was added in approximately proportion to the amount of pellets input, and the slurry At203%:
Try to maintain a range of 18-20%.

Second reduction period: Stop charging the pre-reduced pellets to the melting reduction furnace, keep the bottom blowing gas at KL, and then top blow oxygen at 750ONm/hr, 300ONm/hr every 7 minutes.
C in the slag by changing r-*ONm/hr.
Proceed with the reduction for r, and change the final slag composition to CaO'20
% -8iO22:l, Mg021%, At20
319%, T, Cr: 0.6%, T, Fe: 0.
7%. This slag is removed as an intermediate slag. The molten metal is left behind, and the above-mentioned first and second reduction periods are then repeated, followed by tapping out 2/3 of the molten metal. After that, the same cycle is repeated. The components of the tapped metal are as follows. Cr: 53%, Fe: 37%, C
: 8.5%, St: 0.1%, S: 0.015%
eP: 0.036%.

The discharged molten slag is pulverized, crushed into 1 ounce or less, and
Magnetic selection was carried out at 000 Gauss. The T and Cr of the slag after magnetic separation are 0.3%.

The obtained powder had a soluble silicic acid content of 21% and an alkali content (
CaO ratio + MgO%) = 41%, which satisfies the following component conditions required for a silicate fertilizer.

(i) Soluble silicic acid: 20% or more (11) Alkali content: 35% or more (iii) Maximum amount of chromium = 4% or less (1■9 Amount of chromium per 1.0* of soluble silicic acid 20.1%0

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing an example of equipment used to produce the slag of the present invention, and Figure 2 is the change over time of (T, Cr%) in the slag in the smelting reduction smelting process of the present invention. Figure 3 is an explanatory diagram showing the 70 mm scale experimental equipment used to investigate the influence of slag components on the rate of change of T-C beak in slag. Figure 3 shows an example of changes over time in (T, Cr%) and the definition of characteristic values. Figure 6 is a diagram showing the influence of the slag component on the constant 2ko, Figure 6 is a diagram showing the influence of the slag component on the rate constant = kl during the time period that can be organized by the first order reaction equation in Figure 4, Figure 7 is a diagram showing the influence of the slag component on the constant 2ko. The figure shows (T, Cr%) of powdered slag after water pulverization and magnetic separation,
Patent applicant: Nippon Steel Corporation and one other person 02θ 4θ
6θ lθ 醋閘 (min) ko (%/m7') lctxlθ2 ('mu,・n) Continued from page 1 0 Inventor Noriyuki Inoue To Kitakyushu City 2142-3 Horoka, Maeda, Hatto-ku, Japan Heavy Chemical Industrial Stock % Formula % Oka 2142-3 Inside the Kyushu Plant of Japan Heavy and Chemical Industries Co., Ltd. Applicant Japan Heavy and Chemical Industries Co., Ltd. 8-4 Nihonbashi Koami-cho, Chuo-ku, Tokyo Procedural Amendment (Voluntary) August 10, 1981 Mr. Kazuo Wakasugi, Commissioner of the Japanese Patent Office■, Indication of the case: Patent Application No. 110571, filed in 1982, Title of the invention: Slag used as a soil conditioner 3, Relationship with the person making the amendment: Patent applicant: Chiyoda, Tokyo 2-6-3 Otemachi, Ward (665) Nippon Steel Corporation and 1 other representative Takeshi 1
) Yutaka 4, Agent Address: 2 Marunouchi, Chiyoda-ku, Tokyo 100] Item 4, No. 1, No. 6, Claims column 1 of the specification to be amended, Detailed description of the invention and drawings 7, Contents of the amendment l ) Amend the claims in a separate document. 2) On page 4 of the specification, lines 10-16, "The gist of the present invention is..." shall be amended as follows. ``The present invention uses chromium ore or its semi-reduced product as the main raw material, adds carbonaceous material and flux, and heats it with blowing acid to reduce and melt and separate the chromium and iron, which has a content of 17 to 25%. characterized by satisfying the conditions,
This article focuses on slag used as a soil conditioner. ” 3) Change “0.7 to 1.2” to “0.7 to 1.2” on page 10, line 6.
5". 4) Page 11, line 7 r az2o5<22chi.”
is corrected so that rAt205<25% (particularly preferably 22% or less). 5) On page 11, line 6, "22% or less" is corrected to "25% or less." 6) Change “0.7 to 1.2” to “0.7 to 1.2” on page 11, line 7.
5". 7) Figures 5 and 6 are revised in the appendix. Claims: Chromium ore or its semi-reduced product is used as the main raw material, carbonaceous material and 7 lacs are added, and chromium is removed by heating with blowing acid. and is produced by reducing and melting and separating iron, and is characterized by satisfying the composition condition of 17 to 25%.
Slag used as a soil conditioner. [Rikasumi

Claims (1)

[Claims] It is produced by using chromium ore as the main raw material, adding carbonaceous material and flux, and heating with blowing acid to reduce and melt and separate the chromium and iron. Slag used as a soil conditioner.