JPS5992984A - Manufacture of fused phosphate fertilizer - 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 The present invention relates to an improvement in a method for producing molten phosphorus using an electric furnace.

Conventionally, the method for manufacturing molten phosphorus (hereinafter referred to as molten phosphorus) is to coarsely crush raw materials such as phosphate rock and serpentine into granules and mix them, and then feed this mixed raw material into an electric furnace. A widely used method is to apply a high voltage of several thousand volts through electrodes to melt the material by heating it to 1,300 to 1,500° C., to flow out the resulting molten material from an electric furnace, and then to pulverize it.

However, according to the above method, since expensive electricity is used as a heat source for heating and melting the raw materials, the reality is that the proportion of electricity prices in manufacturing costs is increasing year by year due to the recent rise in electricity prices. There is a desire for a method that can reduce power consumption as much as possible and save energy.

In addition, the molten phosphorus raw material is usually dried at 70 to 80 degrees Celsius before being put into the electric furnace, but even then the moisture content is about 2 to 3%.
When placed in an electric furnace and heated in such a state, the molten material in the furnace often boils due to the generated water vapor. This boiling phenomenon not only poses a safety problem, but is also undesirable from the standpoint of heat loss.

This invention eliminates the drawbacks of the conventional method as described above, reduces the power consumption when melting raw materials in an electric furnace, and saves energy. This was done with the purpose of providing an improved method for producing phosphorus that can prevent the occurrence of molten phosphorus, and its gist is to preheat the molten phosphorus raw material to at least 300°C or higher before charging it into an electric furnace. It is characterized by:

According to the method of the present invention, before the raw materials are introduced into the electric furnace, the raw materials are heated to at least 30% by using a relatively inexpensive heat source.
In an electric furnace that can be preheated to 0°C and uses expensive electricity as a heat source, it is sufficient to heat from 300°C to a melting temperature of 1300 to 1500°C, so raw materials at room temperature can be heated to the melting temperature in an electric furnace. Compared to conventional methods, heat source costs can be significantly reduced. Furthermore, since the raw materials fed into the electric furnace are in an absolutely dry state, boiling phenomena caused by water vapor generation within the electric furnace can be prevented.

Note that the higher the preheating temperature of the raw materials is, the lower the amount of electric horns used in the electric furnace can be. (The preheating temperature in this invention is at least 300°C or higher, preferably at least 300°C, from the viewpoint of obtaining a substantial reduction effect in power consumption and not requiring the use of particularly heat-resistant and expensive equipment.) 400 to 450°C.On the other hand, when preheating to a high temperature of 700°C or higher, not only is a heat-resistant preheating device required, but the raw material also thermally decomposes and generates gas, which is undesirable. .

The invention will now be described in detail with reference to preferred embodiments not shown in the accompanying drawings.

In the preferred embodiment shown, the molten raw material is preheated using the combustion heat of carbonization gas generated by carbonization of organic waste such as old tires. That is, carbonization gas generated by thermal decomposition of old tires in the carbonization apparatus 1 is guided to the combustion chamber 2 and combusted by the auxiliary burner 3 to generate hot air. This hot air is guided to a preheating chamber 5 by a hot air blower 4.

On the other hand, the molten raw material is metered and introduced from the hopper 6 into the preheating chamber 5, where it is preheated with hot air. As the structure of the preheating chamber, various types of heating drying devices such as a band drying device, a rotary drying device, and a fluidized drying device can be adopted, but in the preferred embodiment illustrated, a heating device equipped with a band conveyor 7 is used. .

The raw material heated to a temperature of at least 300° C. in the preheating chamber 5 is put into a conventionally used electric furnace 8, heated and melted by an electrode 9, and the molten material is taken out from a tap hole 10. A glass-like molten product can be obtained by quenching and crushing with water from the water injection nozzle 11.

The present invention will be described in detail below with reference to an experimental example conducted using a small open test electric furnace having a raw material processing capacity of 11,000 kH.

The old tire 31 is heated using the old tire carbonization device 1 as shown in the figure.
) tg and the resulting carbonized gas is combusted in the combustion chamber 2. Using the hot air obtained, the molten phosphorus raw material is heated to 420 to 4 GO'C (average 440°C) in the preheating chamber 5, and then heated to an electric furnace. The mixture was heated to a melting temperature of 1,300 to 1,500°C, melted, and then cooled with water to produce a molten phosphorus product. In this case, the amount of electricity used in the electric furnace was 25% less than the current amount (per ton of product). In addition, it takes approximately 140 minutes to heat and melt raw materials at 440°C in an electric furnace to the melting temperature, and during this time, there is only one small-scale boiling phenomenon in the electric furnace. only was recognized.

On the other hand, for comparison, raw materials (product temperature 17℃) were prepared in the same way as before.
) was put into the electric furnace as it was without preheating, and 1
After heating and melting to a melting temperature of 300 to 1,500°C, the mixture was cooled with water to produce a molten phosphorus product. The electric power consumption in the electric furnace in this case was 1000 KWH/ton of product (including heat radiation loss due to the open test furnace). In addition, 17
It takes about 200 minutes to heat the raw material at ℃ to the melting temperature and heat and melt the raw material, and during this time, there are one large-scale boiling event and one medium-sized boiling phenomenon in the electric furnace. , three small-scale cases were recognized.

As can be seen from the above, according to the method of the present invention, compared to the conventional method in which raw materials are charged into an electric furnace without preheating, it is possible to not only significantly reduce the cost of the heat source (
It is also possible to effectively prevent the occurrence of boiling phenomena caused by water vapor generation within the electric furnace. Conventionally, voltage application to the electrodes has been stopped for 15 to 20 minutes during boiling-state photogeneration for safety reasons, but this method of the present invention, which can prevent the occurrence of boiling phenomena, eliminates such stoppage of voltage application.

Furthermore, compared to the conventional method, according to the method of the present invention, since the raw materials are preheated in advance, the time required for melting in the electric furnace can be reduced by about 25 to 30%, and therefore the production per electric furnace can be reduced by about 25 to 30%. ability can be significantly improved.

In addition, when carrying out the method of this invention, if a large amount of preheated raw material is put into the electric furnace at once, the raw material humidity will drop in the upper part of the furnace. It is desirable to adopt a method in which the melt is melted before it decreases and the melt is continuously tapped. When such a continuous tap method is adopted, the amount of molten material retained in the furnace is reduced, so damage to the furnace wall and electrode holder can be reduced, and repair work for these can be reduced.

[Brief explanation of drawings]

The accompanying drawings are dimensional illustrations of preferred embodiments of the invention. 1... Old tire carbonization device, 2... Carbonization gas combustion chamber,
5... Preheating chamber, 6... Raw material hopper, 8...
Electric furnace.

Claims (1)

[Claims] 1. A method for producing molten phosphorus, which comprises charging a molten phosphorus raw material consisting of phosphate rock and serpentinite into an electric furnace, heating and melting it at 1300 to 1500°C, and then crushing it with water.
A method for producing a molten phosphorus side material, characterized in that the molten phosphorus side raw material is preheated to at least 300°C or higher and then charged into an electric furnace. 2. The method according to claim 1, wherein the preheater '1 is heated using combustion heat of carbonization gas produced by carbonization of organic waste.