CN1180995C - Treatment method of high concentration sulfur dioxide waste liquid - Google Patents

Abstract

The invention discloses a method for treating high-concentration sulfur dioxide waste liquid, aiming at providing a method which can lead the high-concentration sulfur dioxide waste liquid to react with marble or limestone mildly and completely; a treatment method which does not emit sulfur dioxide gas to the environment, does not cause secondary pollution and can convert waste residues into gypsum; the invention is that marble or limestone is crushed into powder with more than 200 meshes, and mixed with water to prepare slurry with the weight ratio of 1: 5, waste liquid is injected from bottom holes of a reaction tank according to the weight ratio of 1: 1 of powder to waste liquid under stirring, air is introduced when the pH value is changed to 6.4 after reaction, then suspension is centrifugally separated to obtain hydrous calcium sulfate, and the hydrous calcium sulfate is prepared into gypsum after roasting.

Description

Treatment method of high concentration sulfur dioxide waste liquid

technical field

The invention relates to a technology for treating industrial waste water, more specifically, it relates to a method for treating high-concentration sulfur dioxide waste liquid.

Background technique

Industrially, high-concentration sulfur dioxide waste liquid comes from the water washing and purification of raw material gas sulfur dioxide; at present, stripping towers are mostly used at home and abroad to recover sulfur dioxide for recycling, and the remaining sewage is sent to sewage treatment plants for treatment or reprocessing. This method requires large investment and high energy consumption, which is unbearable for general medium and small production plants. Therefore, some domestic small and medium-sized manufacturers often directly discharge high-concentration sulfur dioxide waste liquid into rivers, rivers, lakes, and seas without any treatment, causing serious pollution to the environment. High-concentration sulfur dioxide waste liquid is a concentrated solution of strong acid, which will cause serious secondary pollution if it directly reacts with alkali sodium hydroxide solution or lime water. High-concentration sulfur dioxide waste liquid is very unstable, and will volatilize in large quantities into the air when heated. If the high-concentration sulfur dioxide waste liquid is directly reacted with granular marble or limestone, it will be difficult to carry out the reaction to the end, the utilization rate of raw materials is not high, and there will still be a large amount of sulfur dioxide gas released, which will also cause serious secondary pollution.

Contents of the invention

The purpose of the present invention is to provide a kind of can make high-concentration sulfur dioxide waste liquid and marble or limestone can react mildly and completely; do not release sulfur dioxide gas to the environment, will not cause secondary pollution, and can convert its waste slag into gypsum A method for treating high-concentration sulfur dioxide waste liquid.

The purpose of the present invention is to be achieved through the following technical solutions.

The high-concentration sulfur dioxide waste liquid treatment method of the present invention comprises the following steps successively:

(a). One of marble or limestone is crushed into a powder of more than 200 mesh;

(b). In the reaction tank, the above-mentioned powder and water are made into a slurry in a weight ratio of 1:5;

(c). Under stirring, according to the ratio of powder: waste liquid weight 1: 1, inject high-concentration sulfur dioxide waste liquid from the middle and lower part of the reaction tank with holes;

(d). After adding the waste liquid, continue to stir and react until the pH value changes to 6.4, and feed air to oxidize calcium sulfite to calcium sulfate;

(e). Centrifuge to separate the calcium sulfate product containing water;

(f). Calcining the product obtained in step e to make gypsum.

The particle size of step (a) powder is 200 mesh.

The density of the high-concentration sulfur dioxide waste liquid in step (c) is 1.56g/cm ³ -1.64g/cm ³ , the stirring speed is 20-30 rpm, and the high-concentration sulfur dioxide feeding speed is 0.5dm ³ /s.

In the present invention, by improving the technological conditions for the reaction between sulfur dioxide and marble or limestone, the high-concentration sulfur dioxide waste liquid can react mildly and completely with marble or limestone; no sulfur dioxide gas is released to the environment, no secondary pollution is caused, and it can be The waste slag is converted into gypsum, which achieves the beneficial effects of rationally utilizing resources and preventing pollution.

Description of drawings

Fig. 1 is a process flow diagram of the present invention.

In the figure: pulverizer 1 reaction tank 2 waste liquid feeding pipe 3 centrifuge 4 roasting furnace 5

Detailed ways

The present invention will be further described below in conjunction with the accompanying drawings.

According to the technological process as shown in Figure 1, the concrete embodiment of the present invention adopts marble, and the content of its calcium carbonate is not less than 99%, and 1 ton of marble is pulverized into 200 mesh powders in pulverizer 1; In the reaction tank 2 of 10M ³ of 5 tons of water, make a slurry with water; start stirring, and the stirring speed is 25 rpm, and inject 1 ton of density into 1.61g from the porous waste liquid feeding pipe 3 in the lower part of the reaction tank /cm ³ of high-concentration sulfur dioxide waste liquid, the feeding speed is 0.5dm ³ /s; after the feeding is completed, continue to stir the reaction for about 2 hours until the pH value drops to 6.4, and feed air to oxidize calcium sulfite to calcium sulfate; Add the suspension into the centrifuge 4, and centrifuge to separate the hydrous calcium sulfate; put the above-mentioned hydrous calcium sulfate into the roasting furnace 5, and roast it to make gypsum.

Using marble or limestone as raw material to treat high-concentration sulfur dioxide waste liquid, the principle is to use calcium carbonate in marble or limestone to react with high-concentration sulfur dioxide to generate calcium sulfite and release carbon dioxide at the same time. The reaction formula is as follows:

Air is introduced into the reaction tank, and the oxygen in the air oxidizes calcium sulfite to calcium sulfate. The reaction formula is as follows:

Roasting is to remove part of the crystal water of hydrous calcium sulfate to make gypsum. The reaction formula is as follows:

It should be explained why marble or limestone powder of about 200 mesh is used, because the particle size is large, the reaction is incomplete, the utilization rate of raw materials is low, and the purity of the generated calcium sulfate is low; the particle size is too small, and centrifugal separation is difficult. And the processing cost will also increase. If the density of high-concentration sulfur dioxide waste liquid changes, the calcium carbonate content of marble or limestone changes, and its weight ratio can be adjusted appropriately according to the actual situation. A stirring device is added to the reaction tank to fully contact the sulfur dioxide waste liquid with the powder slurry to prevent the local reaction from being too fast and the temperature too high, so that the unreacted sulfur dioxide is released in the form of gas, causing secondary pollution. The stirring speed is preferably 20-30 rpm. At the same time, stirring is also conducive to the release of carbon dioxide and shortens the reaction time. Inject high-concentration sulfur dioxide waste liquid from the middle and lower part of the reaction tank to ensure that the reaction can be fully carried out, and even if a small amount of sulfur dioxide is released, it can be dissolved in water before it rises to the surface of the reaction tank, and the bottom will pollute the air. The flow rate of the sulfur dioxide waste liquid into the reaction tank should be appropriate to prevent the local reaction from being too fast and the temperature too high, so that the unreacted sulfur dioxide is released in the form of gas, causing secondary pollution.

Claims (3)

1. A high-concentration sulfur dioxide waste liquid treatment method, comprising the following steps successively: (a). One of marble or limestone is crushed into a powder of more than 200 mesh; (b). In the reaction tank, the above-mentioned powder and water are made into a slurry in a weight ratio of 1:5; (c). Under stirring, according to the ratio of powder: waste liquid weight 1: 1, inject high-concentration sulfur dioxide waste liquid from the middle and lower part of the reaction tank with holes; (d). After adding the waste liquid, continue to stir and react until the pH value changes to 6.4, and feed air to oxidize calcium sulfite to calcium sulfate; (e). Centrifuge to separate the calcium sulfate product containing water; (f). Calcining the product obtained in step (e) to make gypsum. 2. The processing method according to claim 1, the particle size of step (a) powder is 200 orders. 3. The treatment method according to claim 1 or 2, the density of the high-concentration sulfur dioxide waste liquid described in step (c) is 1.56g/cm ³ -1.64g/cm ³ , and the stirring speed is 20-30 rpm , the feeding rate of high-concentration sulfur dioxide is 0.5dm ³ /s.