CN1102421C

CN1102421C - Process for using iron-series metal oxide as desulfurizing agent

Info

Publication number: CN1102421C
Application number: CN00128048A
Authority: CN
Inventors: 刘振宇; 段东红; 刘守军; 朱珍平
Original assignee: Shanxi Institute of Coal Chemistry of CAS
Current assignee: Shanxi Institute of Coal Chemistry of CAS
Priority date: 2000-11-28
Filing date: 2000-11-28
Publication date: 2003-03-05
Anticipated expiration: 2020-11-28
Also published as: CN1308985A

Abstract

The present invention relates to a method of ferrous series metal oxide used for the desulfurization of flue gas. Industrial ferruginous waste materials are used as main raw materials, prepared desulfurizing agents are placed in a reactor, reaction temperature is controlled to 350 to 450 DEG C, simulation flue gas is led in, the air speed is from 300 to 24000h<-1>, the desulfurizing agents are washed after saturation through sulphre absorption, and the washed desulfurizing agents can be continuously used for desulfurization. Ferric sulfate salt can be obtained by treating aqueous solutions. The present invention avoids regenerative processes with severe conditions and the recovery of SO2, and has the advantages of simple operation, unchanged activity after washing treatment, auxiliary production of ferric sulfate salt and low integrative cost for desulfurization.

Description

Method for using iron series metal oxide as desulfurizing agent

The present invention belongs to an application method of iron series metal oxide desulfurizer.

Dry flue gas desulfurization mostly uses a desulfurizing agent to adsorb or absorb SO in flue gas₂The desulfurizer saturated by absorbing sulfur is regenerated, and high-concentration SO is released during regeneration₂Further processing into sulfuric acid, sulfur or liquid SO₂. Among them, the iron-based metal oxide desulfurizing agents are widely studied, such as Vol27 No 21996, university of Taiyuan Industrial science: 100-101 reports a preparation method using industrial iron-containing waste (such as red mud and the like) as a main raw material. The method has the advantages of abundant raw material sources, simple preparation process, low cost, high desulfurization rate and large sulfur capacity, so that the method is generally concerned. When the iron-based desulfurizer is used for flue gas desulfurization, active components in the desulfurizer, namely iron oxide and SO in flue gas₂And O₂The reaction takes place to produce ferric sulfate salt. With the generation of ferric sulfate salt, the desulfurizing agent gradually loses the desulfurization activity, and needs to be regenerated atthe moment. Chemical metallurgy VOl18 No 31997: the regeneration methods reported by 234-: thermal decomposition regeneration and reduction regeneration. The thermal decomposition regeneration needs to be heated to above 600 ℃ to completely decompose ferric sulfate salt, so that on one hand, the regeneration energy consumption is high, and on the other hand, the high regeneration temperature easily causes the sintering of a desulfurizer, thereby causing the reduction of the secondary desulfurization activity; reductive regeneration by means of reducing gases, e.g. CO, H₂And hydrocarbons, etc., and the ferric sulfate salt is reduced and decomposed at a lower temperature, but the reducing agent has higher cost and is often over-reduced, so that FeS and Fe are generated, and the desulfurization activity is reduced. Both regeneration methods are that ferric sulfate generated by desulfurization is decomposed to release SO₂Therefore, it is necessary to add a complicated SO recovery₂And (6) carrying out the process. Although the research of the iron-based desulfurizing agent is early, the desulfurizing cost is increased due to low utilization rate of iron and harsh regeneration conditions, and sulfur is released in the form of sulfur dioxide in the regeneration process and needs to be further recovered and treated, so that the iron-based desulfurizing agent is not industrially applied at present.

The invention aims to provide a method for using an iron-based desulfurizer, which can completely utilize iron oxide in the desulfurizer without regeneration and can produce a byproduct of ferric sulfate salt.

The purpose of the invention is realized as follows: the industrial iron-containing waste red mud is used as a main raw material, dried, added with a proper amount of adhesive, ground, mixed, extruded and formed, dried and calcined, and then the desulfurizationagent can be used for desulfurization. The prepared iron-based desulfurizer is placed in a fixed bed reactor, the temperature is controlled at 350-^-1Ar is balance gas, and desulfurization reaction is carried out. Cutting off the simulated flue gas at 20-100 deg.C after the desulfurizer is saturated in sulfur absorptionThe water is sprayed and washed for several times, and the desulfurizer after being washed by water can be reused for desulfurization. The desulfurization reaction is as follows: 。

the steps of the method of the invention are described below with reference to the accompanying drawings:

as shown in the figure, 1 is drying, 2 is grinding, 3 is molding, 4 is calcining, 5 is desulfurizing, 6 is washing, 7 is secondary drying, 8 is oxidizing, 9 is reducing, 10 is evaporating, 11 is crystallizing, 12 is filtering, 13 is drying by-product, a is red mud, B is binder, C is desulfurizing agent, D is aqueous solution, E is scrap iron, F is oxygen, H is product, I is sulfur-containing gas, and T is gas after desulfurizing.

The red mud A waste material from factory (such as sulfuric acid plant, iron plant or aluminum plant) is used as raw material, binder B such as starch, lignin or carbon is added, through drying 1 and grinding 2, extrusion forming 3 is carried out on a strip extrusion machine or material forming 3 is carried out in a rotary disc of a sugar coating machine, the granularity is 3-5mm, the obtained formed material is calcined 4 to form desulfurizer C, and desulfurization 5 reaction is carried out in a fixed bed reactor. The composition of the sulfur-containing gas I is: sO₂Is 1150PPm, O ₂5% (V), H₂O is 5 percent (V), the balance gas is Ar, the flow rate is 422ml/min, the desulfurization reaction temperature is 350-450 ℃, and water washing (6) is carried out after thedesulfurization agent absorbs sulfur and is saturated, wherein the water temperature is normal temperature-100 ℃. The water washing is carried out for three times to wash out Fe generated in the desulfurization₂(SO₄)₃After the residual desulfurizer is dried for 7, the residual desulfurizer is used as desulfurization for 5 again; fe obtained by washing with water₂(SO₄)₃The aqueous solution can be treated in two ways: one is oxidation of 8 to Fe₂(SO₄)₂Introducing O into the solution₂Gas makes iron ions completely changed into Fe³⁺First, reduction in Fe₂(SO₄)₂Adding excessive iron filings to the solution to make Fe³⁺All reduced to Fe²⁺Then evaporating 10, crystallizing 11, filtering 12 and drying 13 to obtain the corresponding by-product Fe₂(SO₄)₃Or FeSO₄。

In conclusion, the method comprises four steps, namely, the preparation of the desulfurizer comprises the steps of drying, grinding and molding the raw material red mud; secondly, desulfurization, namely a fixed bed or a moving bed is used; thirdly, washing the desulfurizer saturated in sulfur absorption with water, washing ferric sulfate generated in desulfurization, and drying the residual desulfurizer for continuous use; fourthly, the reduction or oxidation of the solution of ferric sulfate, evaporation, crystallization, filtration and drying.

Compared with the prior art, the invention has the following advantages:

1. no need of regeneration, no high concentration of SO₂Gas is discharged, and SO recovery is omitted₂Complicated post-treatment processes.

2. Through the water washing process, only the desulfurization product ferric sulfate is washed, and the unused active components are notaffected, so that the desulfurization activity after water washing is unchanged.

3. Can remove Fe in the waste₂O₃And SO₂And simultaneously, recycling to generate ferric sulfate salt.

4. The comprehensive cost is greatly reduced.

Example 1

With sulfurAdding starch into red mud which is waste material of acid plant as main raw material, drying, grinding to 200 meshes, placing in a rotary disc of a sugar coating machine, spraying water to form particles with phi of 3-5mm, drying, calcining, taking 1.0 g of prepared desulfurizer, placing in a fixed bed reactor, heating to 380 ℃, keeping constant temperature, and introducing 1150ppm SO₂，5vol.％O₂，5vol％H₂And O, carrying out desulfurization reaction on simulated flue gas (the flow rate is 422ml/min) with Ar as equilibrium gas. Saturated sulfur capacity was 203mg SO₂(ii) in terms of/g. After the desulfurizer is saturated by absorbing sulfur, leaching the desulfurizer by 7ml of water at 20 ℃ for three times, wherein the water amount is 3ml, 2ml and 2ml each time, the corresponding time is 20min, 5min and 5min, then drying the desulfurizer at 110 ℃ for constant weight to obtain 0.86 g of desulfurizer, and the sample is used for desulfurization again under the conditions of the desulfurization temperature and the composition of simulated flue gas, and the secondary saturated sulfur capacity is 223mgSO₂And/g, the washing liquid is evaporated, crystallized, filtered and dried to obtain 0.78 g of solid ferric sulfate.

Example 2

The red mud waste of iron works is used as main raw material, added with lignin, dried and ground, extruded and formed on a strip extruding machine, dried and calcined, 3.0 gof desulfurizer is taken, placed in a fixed bed reactor, heated to 430 ℃, introduced with 1150ppm SO₂，5vol.％O₂，5vol％H₂And O, carrying out desulfurization reaction on simulated flue gas (the flow rate is 422ml/min) with Ar as equilibrium gas. Saturated sulfur capacity was 223mg SO₂(ii) in terms of/g. After the desulfurizer is saturated by absorbing sulfur, leaching the desulfurizer by 45ml of water at 50 ℃ for three times, wherein the water amount is respectively 25ml, 10ml and 10ml each time, the corresponding time is 40min, 10min and 10min, then drying the desulfurizer at 110 ℃ for constant weight to obtain 2.55 g of desulfurizer, and the sample is used for desulfurization again under the conditions of the desulfurization temperature and the simulated smoke composition, and the saturated sulfur capacity is 226mgSO₂And/g, reducing, evaporating, crystallizing, filtering and drying the water washing liquid by using 0.41 g of scrap iron to obtain 2.79 g of solid ferric sulfate.

Example 3

Using waste red mud of aluminum plant as main raw material, adding carbon, drying, grinding, extruding and forming on a strip extruding machine, drying, calcining, taking 5.0 g of desulfurizer, placing in a fixed bed reactor, heating to 450 deg.C, introducing SO whose composition is 1150ppm₂，5vol.％O ₂5 vol% H2O, PingAnd (4) carrying out desulfurization reaction on simulated flue gas (with the flow rate of 422ml/min) with the balance gas of Ar. Saturated sulfur capacity was 247mg SO₂(ii) in terms of/g. After the desulfurizer absorbs sulfur and is saturated, leaching the sulfur-absorbing saturated desulfurizer by 120ml of water at 100 ℃ for three times, wherein the water amount of each time is 60ml, 40ml and 20ml, the corresponding time is 30min, 5min and 5min, then drying the sulfur-absorbing saturated desulfurizer at 110 ℃ for constant weight to obtain 4.3 gof the desulfurizer, and the sample is used for desulfurization again under the conditions of the desulfurization temperature and the simulated smoke composition, and the saturated sulfur capacity is 239mg SO₂And/g, reducing, evaporating, crystallizing, filtering and drying the water washing liquid by using 0.72 g of scrap iron to obtain 5.12 g of solid ferric sulfate.

Claims

1. A method for using iron series metal oxide as dry desulfurizer is characterized in that the method comprises four steps, firstly, the preparation of the desulfurizer comprises the steps of drying, grinding and molding of raw material red mud; secondly, desulfurization, namely a fixed bed or a moving bed is used; thirdly, washing the desulfurizer saturated in sulfur absorption with water, washing ferric sulfate generated in desulfurization, and drying the residual desulfurizer for continuous use; fourthly, the ferric sulfate solution is reduced or oxidized, evaporated, crystallized, filtered and dried.

2. The method of claim 1 wherein said raw red mud comprises iron-containing waste from various industrial plants.