Method for recycling returned sand in soda production
阅读说明：本技术 一种纯碱生产时返砂回收利用的方法 (Method for recycling returned sand in soda production ) 是由 胡玉霆 张元德 马海滨 徐晓兵 任西超 张田田 于 2020-10-26 设计创作，主要内容包括：本发明涉及纯碱生产技术领域,尤其涉及一种纯碱生产时返砂回收利用的方法,包括以下步骤：(1)将返砂中的焦炭核去除；(2)向备用的返砂中加水进行沤制；(3)将沤制完成的原料进行洗涤、过滤,分别收集浆液和固体组分；(4)将粒度大于等于15mm的返砂进行煅烧,再将煅烧后的物料与步骤(2)中收集的浆液置于化灰机内进行反应,过滤收集反应产生的浆液和未参与反应的废渣；(5)将步骤(3)中粒度小于15mm的废渣与步骤(4)中未参与反应的废渣混合后进行研磨,再将研磨后的物料与步骤(4)中反应后产生的浆液混合,作为脱硫剂使用。利用该方法可以将返砂回收利用,降低了对环境的污染,避免了资源浪费。(The invention relates to the technical field of soda production, in particular to a method for recycling returned sand during soda production, which comprises the following steps: (1) removing coke nuclei in the returned sand; (2) adding water into the reserved returned sand for retting; (3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; (4) calcining the return sand with the granularity of more than or equal to 15mm, placing the calcined material and the slurry collected in the step (2) into an ash melting machine for reaction, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction; (5) and (4) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, and mixing the ground material with the slurry generated after the reaction in the step (4) to be used as a desulfurizer. The method can recycle the returned sand, reduce the pollution to the environment and avoid the waste of resources.)
1. A method for recycling returned sand in the production of soda ash is characterized by comprising the following steps:
(1) removing coke nuclei in the returned sand to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than or equal to 15mm and waste residue with the granularity of less than 15 mm;
(4) calcining the return sand with the granularity of more than or equal to 15mm, placing the calcined material and the slurry collected in the step (2) into an ash melting machine for reaction, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material with the slurry generated after the reaction in the step (4), and conveying the slurry into a desulfurizing tower through a conveying pump to be used as a desulfurizing agent.
2. The method for recycling returned sand in the production of soda ash as claimed in claim 1, wherein: the addition amount of return sand and water during retting in the step (2) is 1-1.5m per 30 tons of return sand3Spraying water in the amount of (a) and retting for at least 3 days.
3. The method for recycling returned sand in the production of soda ash as claimed in claim 1 or 2, wherein: and (3) observing the water content in the returned sand at any time in the retting process in the step (2), and supplementing water into the returned sand when dry powder appears, so that the hand feeling is wet.
4. The method for recycling returned sand in the production of soda ash as claimed in claim 1, wherein: when the return sand with the granularity of more than or equal to 15mm is calcined in the step (4), the calcining temperature is 800-950 ℃.
5. The method for recycling returned sand in the production of soda ash as claimed in claim 1, wherein: and (5) the granularity of the ground material is less than 2 mm.
6. The method for recycling returned sand in the production of soda ash as claimed in claim 1, wherein: and (4) the concentration of the slurry conveyed to the inside of the desulfurization tower in the step (5) is 90-130 tt.
7. The method for recycling returned sand in the production of soda ash as claimed in claim 6, wherein: the concentration of the slurry conveyed to the inside of the desulfurization tower in the step (5) is 120-.
Technical Field
The invention relates to the technical field of soda production, in particular to a method for recycling returned sand during soda production.
Background
At present, in the production process of soda ash, the manufacturing procedure of CaO of quicklime is influenced by the granularity, activity, concentration of kiln gas, impurity nodulation and other factors of limestone (CaCO)3) Can not be completely decomposed, finally leads to the generation of a large amount of solid waste return sand after the quicklime (CaO) is digested (about 500 tons of return sand can be generated in a soda plant with the scale of 100 ten thousand tons of soda per year), and the main component of the return sand is CaCO3、CaO、Ca(OH)2. At present, all large soda plants adopt a fixed-point stacking or damming treatment method for return sand, but the two methods do not generate any benefit and cause environmental pollution. Therefore, the recovery of the resources can reduce the waste residue discharge for the soda industry, and is a technical problem which is urgently needed to be solved for soda production enterprises for resource recovery and utilization.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the defects of the prior art, the method for recycling the returned sand during the production of the soda ash is provided, the returned sand can be recycled by using the method, the pollution to the environment is reduced, and the resource waste is avoided.
In order to solve the technical problems, the technical scheme of the invention is as follows:
a method for recycling returned sand in the production of soda ash comprises the following steps:
(1) removing coke nuclei in the returned sand to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than 15mm and waste residue with the granularity of less than 15 mm;
(4) calcining the return sand with the granularity of more than or equal to 15mm, placing the calcined material and the slurry collected in the step (2) into an ash melting machine for reaction, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material with the slurry generated after the reaction in the step (4), and conveying the slurry into a desulfurizing tower through a conveying pump to be used as a desulfurizing agent.
As an improved technical scheme, the addition amount of return sand and water in the retting in the step (2) is 1-1.5m per 30 tons of return sand3Spraying water in the amount of (a) and retting for at least 3 days.
As an improved technical scheme, the water content in the returned sand is observed at any time in the retting process in the step (2), and when dry powder appears, water needs to be supplemented into the returned sand, and the hand feeling is wet.
As an improved technical scheme, when the return sand with the particle size of more than or equal to 15mm is calcined in the step (4), the calcining temperature is 800-950 ℃.
As an improved technical scheme, the granularity of the ground material in the step (5) is less than 2 mm.
As a modified technical scheme, the concentration of the slurry conveyed to the inside of the desulfurization tower in the step (5) is 90-130 tt.
As a preferable technical scheme, the concentration of the slurry conveyed to the inside of the desulfurization tower in the step (5) is 120-130 tt.
After the technical scheme is adopted, the invention has the beneficial effects that:
the invention recovers the return sand during the production of soda ash, removes coke nuclei in the return sand through a jigger, then adds water to wet the return sand, and reacts calcium oxide in the return sand with water to generate Ca (OH)2Simultaneously generate a large amount of heat to ensure that CaCO which is not completely reacted in the return sand3Fully decomposing, adding water into the retted material for washing, filtering and separating, and then respectively collecting slurry and solid components, sieving the solid components to obtain return sand with the granularity of more than 15mm, calcining the return sand in a kiln at 800-950 ℃, fully decomposing the calcium carbonate components in the return sand, mixing and reacting with the slurry, and collecting the reacted slurry and unreacted waste residues; grinding the waste residue with the granularity of less than 15mm and the waste residue which is not fully reacted, and mixing the ground material with the slurry to be used as a desulfurizer in the desulfurizing towerThe use is carried out; by adopting the method, the return sand is recycled, the resource waste is avoided, the discharge of 150000t/a waste sand can be reduced, and the pollution to the environment is reduced; the return sand is used as a desulfurizer after being treated by the method, and the sulfur content of the flue gas after sulfur dioxide is removed is less than or equal to 180mg/m3Every desulfurizing tower can reduce 9000t/a sulfur dioxide emission every year, improve desulfurization efficiency, reduce air environmental pollution, and waste gas discharge to reach standard accords with the requirement of national environmental protection and governance, and the soda production enterprise utilizes the discarded object (return sand) of soda production to be used as the desulfurizer after handling, has reduced the use and the consumption to other desulfurizer, has reduced the desulfurization cost.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A method for recycling returned sand in the production of soda ash comprises the following steps:
(1) placing the returned sand in a jigger, and removing coke nuclei in the returned sand through the jigger to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting; the addition amount of return sand and water is 1m per 30 tons of return sand during retting3Spraying water in the amount of (A) and retting for 3 days; observing the water content in the returned sand at any time in the retting process, and when dry powder appears, supplementing water into the returned sand, and keeping the hand feeling wet;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than 15mm and waste residue with the granularity of less than 15 mm;
(4) placing the returned sand with the granularity of more than or equal to 15mm in a kiln to calcine at 800 ℃, placing the calcined material and the slurry collected in the step (2) in an ash melting machine to react, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material (with the granularity of 1mm) with the slurry generated after the reaction in the step (4), and conveying the slurry (with the concentration of 90-110tt) in the slurry tank to the inside of a desulfurizing tower through a conveying pump to be used as a desulfurizing agent.
Example 2
A method for recycling returned sand in the production of soda ash comprises the following steps:
(1) placing the returned sand in a jigger, and removing coke nuclei in the returned sand through the jigger to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting; the addition amount of return sand and water is 1.2m per 30 tons of return sand during retting3Spraying water in the amount of (A) and retting for 4 days; observing the water content in the returned sand at any time in the retting process, and when dry powder appears, supplementing water into the returned sand, and keeping the hand feeling wet;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than 15mm and waste residue with the granularity of less than 15 mm;
(4) placing the returned sand with the granularity of more than or equal to 15mm in a kiln to calcine at 850 ℃, placing the calcined material and the slurry collected in the step (2) in an ash melting machine to react, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material (with the granularity of 0.5mm) with the slurry generated after the reaction in the step (4), and conveying the slurry (with the concentration of 110 and 120tt) in the slurry tank to the inside of the desulfurization tower through a conveying pump to be used as a desulfurizing agent.
Example 3
A method for recycling returned sand in the production of soda ash comprises the following steps:
(1) placing the returned sand in a jigger, and removing coke nuclei in the returned sand through the jigger to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting; the addition amount of return sand and water is 1.4m per 30 tons of return sand during retting3Spraying water in the amount of (A) and retting for 5 days; observing the water content in the returned sand at any time in the retting process, and when dry powder appears, supplementing water into the returned sand, and keeping the hand feeling wet;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than 15mm and waste residue with the granularity of less than 15 mm;
(4) placing the return sand with the granularity of more than or equal to 15mm in a kiln to calcine at 900 ℃, placing the calcined material and the slurry collected in the step (2) in an ash melting machine to react, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material (with the granularity of 0.5mm) with the slurry generated after the reaction in the step (4), and conveying the slurry (with the concentration of 120 and 130tt) in the slurry tank to the inside of the desulfurization tower through a conveying pump to be used as a desulfurizing agent.
Example 4
A method for recycling returned sand in the production of soda ash comprises the following steps:
(1) placing the returned sand in a jigger, and removing coke nuclei in the returned sand through the jigger to obtain returned sand for later use;
(2) adding water into the reserved returned sand for retting; the addition amount of return sand and water is 1.5m per 30 tons of return sand during retting3Spraying water in an amount of 6 days for retting; observing the water content in the returned sand at any time in the retting process, and when dry powder appears, supplementing water into the returned sand, and keeping the hand feeling wet;
(3) washing and filtering the retted raw materials, and respectively collecting slurry and solid components; screening the collected solid components to obtain return sand with the granularity of more than 15mm and waste residue with the granularity of less than 15 mm;
(4) placing the return sand with the granularity of more than or equal to 15mm in a kiln to calcine at 950 ℃, placing the calcined material and the slurry collected in the step (2) in an ash melting machine to react, and filtering and collecting the slurry generated by the reaction and waste residues which do not participate in the reaction;
(5) and (3) mixing the waste residue with the granularity of less than 15mm in the step (3) with the waste residue which does not participate in the reaction in the step (4), grinding, mixing the ground material (with the granularity of 1mm) with the slurry generated after the reaction in the step (4), and conveying the slurry (with the slurry concentration of 130-.
In order to better prove that the returned sand treated by the method of the invention has better desulfurization effect as a desulfurizing agent, 3 comparative examples are provided at the same time, and the slurry in the step (5) in the process method in the comparative examples 1-3 and the examples 1-4 is respectively conveyed to a desulfurizing tower (wherein the inlet flue gas air inflow of the desulfurizing tower is about 30000 m) according to the same operation mode3H, sulfur content of about 3700mg/m3The inlet gas temperature is 125-130 ℃), and the specific desulfurization efficiency is shown in Table 1.
Comparative example 1
The desulfurizing agent (the main component is calcium oxide) is prepared into slurry and then is conveyed to a desulfurizing tower for spraying.
Comparative example 2
The difference from example 3 is: the slurry delivered to the desulfurization tower had a consistency of less than 90tt, and the rest of the operation was the same.
Comparative example 3
The difference from example 3 is: the slurry delivered to the desulfurization tower had a consistency of greater than 140tt, and the rest of the operation was the same.
TABLE 1
Examples
Sulfur content of desulfurized flue gas
Efficiency of desulfurization
Example 1
175mg/m3
96.37％
Example 2
170mg/m3
96.50％
Example 3
164mg/m3
97.24％
Example 4
163mg/m3
97.26％
Comparative example 1
185mg/m3
96％
Comparative example 2
190mg/m3
94.86％
Comparative example 3
163mg/m3
97.25％
As can be seen from the data in Table 1, the slurry obtained by treating the return sand by the method of the invention has a good desulfurization effect when used as a desulfurizing agent, the desulfurization efficiency of the slurry prepared by the process methods of examples 1 to 4 is over 96 percent and can reach over 97 percent at most when used as the desulfurizing agent, and the sulfur content of the desulfurization flue gas is less than 180mg/m3The desulfurization effect is better than that of the commercial desulfurizer sold in the comparative example 1 and that of the slurry in the comparative example 2; although the slurry after the sand return treatment has better desulfurization effect under the process method of the comparative example 3, the desulfurization efficiency is not much improved compared with the slurry of the example 3 (the concentration of the slurry is 120-130tt) and the slurry of the example 4 (the concentration of the slurry is 130-140 tt).
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.