JPH0781937A - Desulfurizing method of lead compound captured from waste gas - Google Patents

Abstract

PURPOSE:To easily desulfurize lead compd. dust and use the same as the starting material of glass by adding silica stone powder to the lead compd. dust which is captured from waste gas and incorporated with sulfur oxide, mixing and burning at a prescribed temp. CONSTITUTION:The silica stone powder having 10-50mum average particle diameter is added to the lead compd. dust by >=2/3 weight per the dust and mixed uniformly to obtain a mixture. Then, the mixture is burnt at >=1100 deg.C with an electric furnace, etc., to desulfurize and to obtain a burned lead dust. Then, the dust is pulverized and classified and used as the starting material of a lead glass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for desulfurizing lead compound dust containing sulfur oxides collected from the exhaust gas of a continuous lead glass melting furnace by a heavy oil combustion system.

[0002]

2. Description of the Related Art Conventionally, when manufacturing lead glass, glass materials such as silica sand and lead oxide are supplied to a continuous glass melting furnace,
A method of melting by a heavy oil combustion method is adopted, but this method produces dust called lead compound dust. Therefore, in order to prevent the release of lead compound dust into the atmosphere, it is collected using an electric dust collector.

By the way, most of the components of lead compound dust are
It is a compound of lead oxides evaporated from molten glass and sulfur oxides contained in the combustion gas of heavy oil, and is usually 64 to 72% by weight of lead oxides, 23 to 28% of sulfur oxides, and 0 to 10 others. %. Therefore, the lead compound dust collected from the exhaust gas cannot be disposed of as industrial waste.

Therefore, attempts have been made to reuse the lead compound dust as a glass raw material.

[0005]

Generally, when the proportion of sulfur oxides in the molten glass exceeds 0.20% by weight, a reaction product of sulfur oxides and alkali metal oxides called gall is formed on the glass melt surface. It is known that they are easily generated and cause glass defects. Therefore, the lead compound dust containing a large amount of sulfur oxide can be used only in a very small amount as a glass raw material. However, since the amount of lead compound dust generated is relatively large at about 1 to 3% by weight with respect to the amount of glass melted, it is difficult to consume all of these as glass raw materials.

An object of the present invention is to provide a method for desulfurizing lead compound dust so that the whole amount of the collected lead compound dust can be consumed as a glass raw material.

[0007]

As a result of various experiments, the present inventor found that the above object can be achieved by adding silica stone powder to lead compound dust and firing at a certain temperature or higher. It is a proposal.

That is, the method for desulfurizing lead compound dust collected from exhaust gas according to the present invention is such that silica powder is added to lead compound dust containing sulfur oxides collected from exhaust gas, and the mixture is uniformly mixed, then at 1100 ° C. or higher. It is characterized by firing at the temperature of.

[0009]

The desulfurization method of the lead compound dust collected from the exhaust gas of the present invention is such that when silica powder is added to lead compound dust containing sulfur oxides and fired, the sulfur content is gasified and separated,
A compound of lead oxide and silicon oxide is formed. The gasified sulfur content can be collected and reused by a generally known method such as gas cleaning.

The method of the present invention will be described in detail below.

First, silica stone powder is added to lead compound dust. The silica stone powder to be added has an average particle size of 10 to 50 μm.
It is preferable to use the one of The addition ratio of the silica stone powder to the lead compound dust is preferably 2/3 or more in weight ratio, but it is desirable to make the silica stone powder the same weight as the lead compound dust for the most efficient desulfurization. If the proportion of silica powder is too small, the lead compound dust after firing (hereinafter referred to as fired lead dust) hardens and becomes difficult to pulverize.
It becomes difficult to use as a glass raw material.

Next, this mixture is mixed uniformly.

Thereafter, the mixture is fired at a temperature of 1100 ° C. or higher, preferably 1200 ° C. or higher. The firing temperature is set to 1100 ° C. or higher because the sulfur content is hardly separated when firing at a temperature lower than this.

The fired lead dust thus obtained can be used as a raw material for lead glass by pulverizing and classifying it so that it has an appropriate particle size.

[0015]

EXAMPLES The present invention will be described below based on examples.

First, lead compound dust (PbO 68%,
The same weight of silica stone powder (SiO ₂ 99% or more) for glass raw material was added to SO ₃ 24% and other 8%), and mixed uniformly. The silica stone powder used had an average particle size of 20 μm.

Next, these were fired in an electric furnace at the temperatures shown in Table 1 for 1 hour, and the content of sulfur oxide in the fired lead dust was measured.

[0018]

[Table 1]

As is apparent from Table 1, the sample No. No. fired at a temperature of 1100 ° C. or higher was used. It was found that the contents of sulfur oxides in the dusts 3 and 4 were drastically reduced. Especially 1
Sample No. fired at a temperature of 200 ° C. In the dust of No. 4, the sulfur oxide content was extremely reduced to 0.2%, which was 1/60 of that of the unburned dust. On the other hand, 90
Sample No. fired at 0 to 1000 ° C. The dusts of 1 and 2 had almost no change in the sulfur oxide content.

Next, sample No. In the case where the lead glass was melted by using the burned lead dusts of 3 and 4 as a glass raw material (Samples A to D), it was examined whether or not the goal was generated. Further, for comparison, in the case where 1% of lead compound dust was used (Sample E), it was examined whether or not the goal was generated. The results are shown in Table 2.

[0021]

[Table 2]

As is clear from Table 2, in the sample E using 1% of the lead compound dust, the formation of gall was recognized.
On the other hand, sample No. No formation of gall was observed in Sample A in which 2% of the burned lead dust of 3 was used. Sample N
o. In the case of using the burned lead dust of No. 4, no formation of gall was observed in the molten glass even in Sample D in which 10% was used.

The proportion of each component of the calcined lead dust was determined by fluorescent X-ray analysis. The presence or absence of goal generation was evaluated as follows. First, weight% SiO ₂ 57%, P
bO 29%, Na ₂ O 8.2%, K ₂ O 4.5%,
Al ₂ O ₃ 1%, Sb ₂ O ₃ 0.3% so that silica sand, lead oxide, soda ash, potassium carbonate, alumina,
Mix soda sol, antimony trioxide, and calcined lead dust (or lead compound dust) in the proportions shown in the table, put them in a platinum crucible,
It was melted at 1450 ° C. for 4 hours in an electric furnace. Then, the molten glass was poured onto a surface plate to prepare a plate-shaped sample, and after annealing, the surface was observed with a stereomicroscope and no glass defects were found. It is assumed that a goal has been generated.

[0024]

As described above, according to the method of the present invention, the lead compound dust can be desulfurized by a simple treatment. Therefore, the whole amount of the lead compound dust generated during the production of the lead glass is used as the glass raw material. It can be consumed.

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Claims (1)

[Claims] 1. After adding silica stone powder to lead compound dust containing sulfur oxides collected from exhaust gas and uniformly mixing,
A method for desulfurizing lead compound dust collected from exhaust gas, which comprises calcination at a temperature of 1100 ° C. or higher.