JPS5940209B2 - How to remove phosphorus from ore - Google Patents

Description

Detailed Description of the Invention The present invention mainly uses iron ore, titanium-containing iron ore, nickel-containing ore, chromium-containing ore, or these ores for the purpose of obtaining low-phosphorus iron or ferroalloy raw materials from relatively high-phosphorus ores. The present invention relates to a method for selectively volatilizing and removing phosphorus from a mixture of components.

The ore, which is a raw material for iron manufacturing and ferroalloy, is usually strongly reduced with a carbonaceous reducing agent before use, so the phosphorus contained in the raw material ore is completely reduced and contained as an impurity in the iron or ferroalloy. .

As is well known, the adverse effects of phosphorus on steel materials are extremely large, causing low-temperature embrittlement and tempering embrittlement, and deteriorating corrosion resistance and weldability.

Therefore, it is desirable that the raw material ore used in the production of iron or ferroalloy contains as little phosphorus as possible.

Conventionally known methods for removing phosphorus from ores include crushing the ore and subjecting it to magnetic beneficiation, or grinding and then elutriation and magnetic beneficiation. The decline is also not that noticeable.

Therefore, phosphorus is usually removed during the steelmaking stage by oxidizing and refining basic slag.

However, when raw material ore with high phosphorus content is used,
It is difficult to achieve extremely low phosphorus levels through conventional smelting, and requires a double slag smelting method or a special dephosphorization smelting method, which complicates the smelting process and reduces productivity.

The impurity P in ores usually exists as a phosphoric acid compound such as Ca3(PO4)2.

As a result of various studies, the inventor found that the CaO content was 2 by weight.
5% or less, and Ca O/(S i 02 + A 40
3) Phosphate compounds in ores with a composition ratio of 5 or less are thermally decomposed at extremely high temperatures, evaporated as gaseous compounds with high vapor pressure, such as PO, and can be removed into the gas phase by a gas flow. , or when using a reducing gas,
Phosphate compounds in the ore are reduced to phosphite compounds (P
It was discovered that phosphorus (P) can be removed into the gas phase by a gas flow.

Can the dephosphorization according to the present invention be carried out at a temperature of 1600°C or higher?18
The temperature is preferably 00°C or higher.

Although it is difficult to achieve such a high temperature range by ordinary heating methods, it can be achieved by using, for example, plasma arc or high-frequency induction plasma.

When carrying out the present invention using a plasma arc, the ore is processed in a molten state, so any form of powder, lumps, pellets, etc. can be used.

The procedure for implementing the present invention using a plasma arc is to first charge ore into a container, irradiate the plasma arc from above to melt the ore, and then hold the molten ore in the container for a certain period of time until the Treated by exposure to high temperature plasma arc gas.

For charging the ore into the container, the entire amount of the ore to be treated may be charged into the container in advance, or a portion of the ore may be continuously charged to a molten diameter.

For continuous charging, it is convenient to charge directly into the container, but
Grind some of the ore or sieve the powdered ore to 100
It is also possible to process the ore powder by feeding it into a plasma arc together with gas, melting it in the ultra-high temperature part of the arc, placing it in a container, and then holding it in the container for a certain period of time.

The reason why the amount of powdered ore is 100 mesh or less is to stably feed ore particles into the plasma arc using gas.
This is to maintain sufficient melting of ore particles within the arc.

When processing ore in large quantities using plasma arc,
An effective method is to use a combination of direct charging into the container and feeding into the plasma arc.

When implementing the present invention using high-frequency induced plasma, the ore is treated in powder form.

After the ore is crushed or the powdered ore is sieved to a size of 100 mesh or less, the ore powder is continuously fed into a high-frequency induced plasma using a known powder feeding device for treatment.

Feeding ore powder into high-frequency induced plasma is easier than feeding into a plasma arc, and a large amount of ore can be fed.

When implementing the present invention using high frequency induced plasma,
Dephosphorization can be achieved simply by passing the ore powder through plasma, melting it for a short time in an extremely high temperature section, and solidifying it in a low temperature section.

The ore after treatment may be received in a container and remelted, or may be recovered as a powder.

The container used in the present invention can be either a metal container or a refractory container, but when a metal container is used, the outer wall of the container needs to be cooled with water to prevent melting damage caused by heated molten ore.

In addition, when using a large-sized container, it is necessary to control the heat dissipation of the container to form a thin layer of unmolten ore on the inner wall of the container in order to prevent erosion due to reaction with molten ore, and cool it with a water cooling jacket, etc. It is preferable.

The rate of dephosphorization according to the present invention is based on the CaO contained in the ore.
, 5i02. It varies depending on the Al2O3 content.

According to the research of the present inventor, 25% or more by weight of CaO
In the case of an ore containing CaO or an ore with a CaO/(S102+A1203) ratio of 5 or more even if the CaO content is 25% or less, dephosphorization is not performed.

However, if the CaO content is 25% or less, and CaO/(S1
02+A1203) when the ratio is less than 5, dephosphorization occurs.

Since CaO inhibits dephosphorization, the lower the content, the better.

Also, in the same -CaO content, CaO/(S102+A
1203) The smaller the ratio, the higher the dephosphorization rate.

However, SiO□. Although Al2O3 is a component that inhibits dephosphorization, the total amount is 50% by weight.
It is preferable that it is below.

As a method of utilizing the ultra-high temperature of plasma, for example, Ar
A thermal decomposition method such as rS + 03) or a method of melting and reducing iron ore, chromium-containing ore, and nickel-containing ore using a plasma arc containing H2 or hydrocarbon gas is already known.

The purpose of the former is to change the crystal structure by thermal decomposition into a crystal structure that makes it easy to separate two components.For example, taking the thermal decomposition method of rosette, after changing the crystal structure as shown in the following formula, , is a method of obtaining Mn by dissolving MnO in hydrochloric acid (MnSiO3→MnO+5i02) and extracting it. This method simply utilizes the thermal decomposition reaction caused by the extremely high temperature of a plasma arc as a method of converting valuable metals into a form that is easy to recover.

At present, no method has been found for selectively volatilizing and removing impurity elements, especially phosphorus in ores, as in the present invention.

The latter smelting reduction method is aimed at the reduction production of iron, chromium, nickel, etc., and conventionally, no strong attention has been paid to the removal of impurities.

The present inventor did not intend to reduce ore, but completed the present invention after studying various preliminary dephosphorization methods for ore. is not essential.

Even when reducing gas is used, the amount of reducing gas used is smaller than in the smelting reduction method.

For example, if we compare the method of melting and reducing iron ore using hydrogen plasma and the method of the present invention that utilizes the ultra-high temperature of hydrogen plasma, and describe the differences, 'I'Fe in iron ore is usually 60
%, and the hydrogen utilization efficiency in hydrogen plasma smelting and reduction is 50 to 70%, so the amount of hydrogen required for reduction is 90 to 12 ONl per 100 g of ore.

Furthermore, hydrogen plasma smelting reduction has a hydrogen utilization efficiency of 20% when reducing difficult-to-reducible ores such as chromium-containing ores.
Since the chromium-containing ore decreases to below, it becomes virtually impossible to reduce the chromium-containing ore.

In contrast to the above smelting reduction method, the method of the present invention can be applied not only to iron ores but also to difficult-to-reducible chromium-containing ores, when the CaO content is 25% or less and the strain CaO/(SiO□+A#)s) ratio is 5 or less. ore, the amount of hydrogen gas required to remove 60% or more of phosphorus in the ore is 5 ONl or less per 100 g of ore, regardless of the type of ore.

Naturally, if the amount of gas used is small, the time required for processing will also be shortened.

As described above, the present invention is different from the known pyrolysis method or smelting reduction method using a plasma arc, and the ore dephosphorized according to the present invention may be used as a raw material for low-on iron or ferroalloy. It can also be used as an auxiliary raw material for steel manufacturing.

In carrying out the present invention, 16 gases or reaction points are used.
The means to raise the temperature to 00°C or higher is not limited to the use of plasma arc or high-frequency induction plasma, but can also be achieved by concentrated heating using lasers, image arcs, etc., heating by combustion of methane, etc., and even under reduced pressure. If the present invention is implemented, more effective dephosphorization can be expected.

Actual boat example 1 All fired pellets containing iron ore, titanium-containing iron ore, chromium-containing ore, and nickel-containing ore as main components were initially charged into a water-cooled iron mold, and then subjected to direct current Ar gas arc plasma.
Dephosphorization treatment was carried out by irradiation with r-N2 mixed gas arc plasma and Ar-N2 mixed gas arc plasma.

During processing, molten ore was continuously sampled and analyzed for P.

The analytical values for each ore are shown in Table 1, and the experimental conditions are shown in Table 2.
The results are shown in Figure 1.

Note that the numbers in FIG. 1 indicate the numbers shown in Table 2.

Example 2 Calcined iron ore pellets 3 having the same composition as shown in Example 1
00g was placed in a water-cooled iron mold and irradiated with Ar H2 mixed gas arc plasma to melt the entire amount in 5 minutes.

Iron ore calcined pellets 30 (150-250 after melting L9)
Iron ore sized into mesh (T-Fe62.39%, P
o, 16%, CaO3, 40%, Sin.

4.02%, A42030.62%) at 100g/mi
t> Feed into the Ar-H2 mixed gas arc plasma for 20 minutes at a feed rate, receive it in a water-cooled iron mold, and after stopping the feed,
The mixture was mixed and melted for a minute to perform dephosphorization treatment.

During processing, the molten ore inside the water-cooled iron mold is continuously collected.
was analyzed.

The plasma arc conditions are shown below, and the results are shown in FIG.

Plasma arc conditions Plasma arc gas A r 74/mi! t+H25
1)/mm fine ore feed gas Ar 30 l/mi
n plasma plasma arc gas 50A-65V example
3 Iron ore sized to 150-250 mesh ('1.''・
Fe 63.54%, Po, 127%, Ca00.34
%, Si025.90%, A42030.19%, M
g00.26%) was fed into high frequency induction plasma for dephosphorization treatment.

The processed ore powder was collected in an iron mold, and after the entire amount was processed, an analysis sample was taken from the center of the mold.

As a result, the P content was 0.013% (dephosphorization rate 90%).

Experimental conditions are shown below. High frequency oscillator output 35
kW Ar gas flow rate s o Nl/min Ore feeding rate 309 /mlyr Processing time
20 minutes ore processing amount 610g Example 4 500g each of calcined iron ore pellets with different contents of CaO2SiO2 and Al2O3 were initially charged in a water-cooled iron mold, and Ar-H2 mixed gas (DC 250A-65V) was charged.
Ar7. Ol/mlyv+H25,01)/mi
n) Dephosphorization treatment was performed by irradiating with arc plasma.

During processing, molten ore was continuously sampled and analyzed for P.

The analytical values of each fired pellet are shown in Table 3, and the results are shown in FIG.

The numbers in the figure indicate the pellet numbers shown in Table 3, and as a result, dephosphorization was not performed when the CaO content was 25% or more (6).

CaO content is 25% or less and CaO/(S i02
+Al2O3) ratio of 5 or less, the lower the CaO content, the better the dephosphorization.

In addition, the same -CaO content (2°3.4), CaO
/(S102+A1203) The smaller the ratio, the better the dephosphorization.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between processing time and phosphorus content when ore composition or plasma arc conditions are changed when implementing the present invention using a plasma arc, and Figure 2 is a diagram showing the relationship between processing time and phosphorus content when the ore composition or plasma arc conditions are changed. Figure 3 is a diagram showing the relationship between processing time and phosphorus content when some of the ore is charged into a container and some of the ore is pulverized and fed into the plasma arc. In implementing the present invention using a plasma arc, the CaO content or Ca
It is a figure which shows the relationship between processing time and dephosphorization rate when O/(S102+A1203) ratio is changed.

Claims (1)

[Claims] I CaO content is 25% or less by weight and Ca
Iron ore, titanium-containing iron ore, nickel-containing ore, chromium-containing ore, or a mixture containing these ores as main components, with an O/(S 102 + k1203) ratio of 5 or less;
, He, N2, CO, N2, one type of hydrocarbon, or a mixed gas flow thereof at a temperature of 1600° C. or higher.