Composite functional additive suitable for cement kiln to co-process heavy metal-containing waste

Abstract

The invention discloses a composite functional additive suitable for co-processing heavy metal-containing waste in a cement kiln, and belongs to the technical field of cement manufacturing. The composite functional additive comprises the following components in parts by mass: 30-50 parts of a mineralization component, 30-50 parts of a heavy metal adsorption component and 10-20 parts of a high-temperature-resistant component. Wherein the mineralization component comprises CaF2, SrO, ZnO and MgO, and the mineralization component comprises CaF2, SrO, ZnO and The heavy metal adsorption component comprises attapulgite, bauxite and calcium oxide; the high-temperature-resistant component comprises aluminum oxide and fly ash. Through scientific research and practical inspection, the composite functional additive with the heavy metal curing and mineralizing functions is successfully prepared, and the process safety and clinker product quality of the cement kiln for co-processing the heavy metal-containing waste can be improved.

Description

Technical Field

[0001] The invention belongs to the technical field of cement manufacturing, and in particular relates to a composite functional additive suitable for co-disposal of heavy metal-containing wastes in cement kilns. Background Art

[0002] Cement kiln co-treatment refers to the use of waste to replace raw materials and fuels in the production of cement clinker, using cement rotary kilns as carriers to achieve efficient and harmless disposal of solid waste through high-temperature incineration and high-temperature sintering of cement clinker mineralization. Its treatment temperature is high (1450℃) and the material residence time is long. Therefore, cement kiln co-treatment can completely decompose dioxins and achieve stable solidification of heavy metals through the clinker mineralization process. Another significant advantage of cement kiln co-treatment is that waste is directly converted into products, solving the problem of secondary utilization of slag.

[0003] Wastes generated by non-ferrous metal mining and smelting, lead-acid battery manufacturing, leather and its products, chemical raw materials and chemical products manufacturing, and electroplating industries are important sources of heavy metal pollution. The heavy metals they contain mainly include Pb, Cu, Cd, Zn, Ni, Cr, Mn, Hg, etc. According to the volatility of heavy metals at high temperatures, they can be roughly divided into volatile heavy metals (Hg, Se), semi-volatile heavy metals (Cd, Pb, As, Zn, etc.) and non-volatile heavy metals (Cr, Cu, Mn, Co, Ni, etc.). Non-volatile heavy metals have a high melting point and are not easy to volatilize at high temperatures. They are more stably solidified in the slag; however, volatile heavy metals and most semi-volatile heavy metals are converted into gases at high temperatures and are easily attached to fly ash. This problem exists in processes such as incineration and cement kiln co-disposal, and the environmental problems caused by it have attracted the attention of many scholars at home and abroad. In addition, solidifying heavy metals in clinker may reduce the content of C3S mineral phase in clinker and increase the content of C2S phase and f-CaO, which will have an adverse effect on its strength. In general, the use of cement kilns to co-dispose of heavy metal-containing wastes faces the dual problems of low heavy metal solidification rate, which leads to the enrichment of heavy metals in the kiln and endangers the safety of equipment, and reduces the strength of clinker and affects the quality of clinker. Summary of the invention

[0004] In view of the above technical problems, the present invention proposes a composite functional additive suitable for cement kiln co-treatment of heavy metal-containing wastes, which can improve the process safety and clinker product quality of cement kiln co-treatment of heavy metal-containing wastes.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] One of the purposes of the present invention is to provide a composite functional additive suitable for cement kiln co-disposal of heavy metal-containing waste, which comprises the following components by weight: 30-50 parts of mineralization component, 30-50 parts of heavy metal adsorption component and 10-20 parts of high temperature resistant component.

[0007] The composite functional adsorbent provided by the present invention comprises clay minerals and high-temperature resistant minerals with porous structures, which can play an excellent heavy metal adsorption role in the high-temperature environment of cement kilns and inhibit the volatilization and condensation of heavy metals; it also comprises mineralized components, which can promote the decomposition of calcium carbonate, reduce the clinker burning temperature by about 50°C to 100°C, promote the formation of tricalcium silicate minerals, and improve the strength and gelling properties of clinker; in addition, the mineralized components can reduce the calcination temperature and also have the effect of reducing the volatilization of heavy metals. At the same time, the clay minerals and high-temperature resistant minerals can improve the strength of clinker by increasing the Al / Si ratio of clinker minerals. At the same time, through the synergistic effect of multiple components, the volatilization and condensation of heavy metals are inhibited, the enrichment and external discharge of heavy metals in the kiln are reduced, and the safety of the cement kiln coordinated disposal of heavy metal-containing wastes is effectively improved.

[0008] Furthermore, the mineralized components include the following raw materials in parts by mass: 0.5-0.8 parts of CaF2, 0.1-0.2 parts of SrO, 0.05-0.2 parts of ZnO and 0.05-0.2 parts of MgO.

[0009] Furthermore, the heavy metal adsorption component includes the following raw materials, measured by weight: 0.4-0.6 parts of attapulgite, 0.2-0.3 parts of bauxite and 0.2-0.3 parts of calcium oxide.

[0010] Furthermore, the high temperature resistant component comprises the following raw materials in parts by mass: 0.3-0.5 parts of alumina and 0.5-0.7 parts of fly ash.

[0011] The second object of the present invention is to provide a method for preparing a composite functional additive for the coordinated disposal of heavy metal-containing waste in cement kilns, comprising the following steps: weighing a mineralizing component, a heavy metal adsorption component and a high temperature resistant component according to a mass ratio, mixing them evenly, and obtaining a composite functional additive.

[0012] The third object of the present invention is to provide an application of the composite functional additive for the coordinated disposal of heavy metal-containing wastes in cement kilns in the field of coordinated disposal of heavy metal-containing wastes in cement kilns.

[0013] Furthermore, 0.5-1% of the composite functional additive by weight of the cement raw material is added during the cement raw material batching process, and then pre-decomposition, calcination and rapid cooling are performed to obtain cement clinker.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects:

[0015] Through scientific research and practical testing, the present invention successfully prepares a composite functional additive with both heavy metal solidification and mineralization functions, which can improve the process safety and clinker product quality of cement kiln coordinated disposal of heavy metal-containing wastes.

[0016] The method of the invention has readily available raw materials, simple process steps, is easy to promote and apply on a large scale, has low cost, is widely applicable, and has good economic and social benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0018] Figure 1 This is the calcination experimental device of the present invention. DETAILED DESCRIPTION

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] The embodiment of the present invention provides a composite functional additive suitable for cement kiln coordinated disposal of heavy metal-containing waste, which includes the following components by weight: 30-50 parts of a mineralization component, 30-50 parts of a heavy metal adsorption component and 10-20 parts of a high temperature resistant component.

[0025] Exemplary, in the following preferred embodiments of the present invention:

[0026] The composite functional additive comprises 30 parts, 40 parts, 50 parts or any range or sub-range between the aforementioned proportions of mineralized components;

[0027] The composite functional additive contains 35 parts, 45 parts, 50 parts or any range or sub-range between the aforementioned proportions of heavy metal adsorption component;

[0028] The composite functional additive comprises 15 parts, 20 parts or any range or sub-range between the above proportions of the high temperature resistant component.

[0029] In some feasible embodiments, the mineralized components include the following raw materials, measured by weight: 0.5-0.8 parts of CaF2, 0.1-0.2 parts of SrO, 0.05-0.2 parts of ZnO and 0.05-0.2 parts of MgO.

[0030] Exemplary, in the following preferred embodiments of the present invention:

[0031] The mineralized component comprises 0.5 parts, 0.7 parts, 0.8 parts or any range or sub-range therebetween of CaF2;

[0032] The mineralized component comprises 0.1 part, 0.15 part, 0.2 part or any range or sub-range therebetween of SrO;

[0033] The mineralized component comprises ZnO in an amount of 0.05 parts, 0.1 parts or any range or sub-range therebetween;

[0034] The mineralized component comprises MgO in an amount of 0.05 parts, 0.2 parts or any range or sub-range therebetween.

[0035] In some feasible embodiments, the heavy metal adsorption component includes the following raw materials, measured by weight: 0.4-0.6 parts of attapulgite, 0.2-0.3 parts of bauxite and 0.2-0.3 parts of calcium oxide.

[0036] Exemplary, in the following preferred embodiments of the present invention:

[0037] The heavy metal adsorption component comprises 0.4 parts, 0.5 parts, 0.6 parts or any range or sub-range between the aforementioned proportions of attapulgite;

[0038] The heavy metal adsorption component comprises 0.2 parts, 0.25 parts, 0.3 parts or any range or sub-range between the aforementioned proportions of bauxite;

[0039] The heavy metal adsorption component comprises calcium oxide in an amount of 0.2 parts, 0.25 parts, 0.3 parts or any range or sub-range therebetween.

[0040] In some feasible embodiments, the high temperature resistant component includes the following raw materials, measured in parts by mass: 0.3-0.5 parts of aluminum oxide and 0.5-0.7 parts of fly ash.

[0041] Exemplary, in the following preferred embodiments of the present invention:

[0042] The high temperature resistant component comprises 0.3 parts, 0.4 parts, 0.5 parts or any range or sub-range between the aforementioned proportions of aluminum oxide;

[0043] The high temperature resistant component comprises fly ash in an amount of 0.5 parts, 0.6 parts, 0.7 parts or any range or sub-range between the aforementioned proportions.

[0044] The preparation method of the composite functional additive for cement kiln coordinated disposal of heavy metal-containing wastes comprises the following steps: weighing a mineralization component, a heavy metal adsorption component and a high temperature resistant component according to a mass ratio, mixing them evenly, and obtaining the composite functional additive.

[0045] The composite functional additive for cement kiln coordinated disposal of heavy metal-containing waste can be applied in the field of cement kiln coordinated disposal of heavy metal-containing waste.

[0046] In some feasible embodiments, 0.5-1% of the composite functional additive by weight of the raw cement is added during the batching process of the raw cement, and then pre-decomposed, calcined, and rapidly cooled to obtain cement clinker. For example, in the following preferred embodiments of the present invention, the amount of the composite functional additive added can be selected to be 0.5%, 0.8%, or 1%.

[0047] The specific operation process of the pre-decomposition is: the raw material is heated to about 800°C by a multi-stage cyclone preheating system, and the preheated raw material enters the decomposition furnace, and the decomposition furnace temperature is controlled at 820-900°C for 1-1.5 hours. Exemplarily, in the following preferred embodiments of the present invention, the decomposition furnace temperature can be set to 850°C, and the residence time is selected to be 1.2 hours. This time is the laboratory high-temperature furnace simulation experiment time.

[0048] The calcination conditions are: temperature 1350-1400°C, time 1-2h. For example, in the following preferred embodiments of the present invention, the calcination temperature can be set to 1350°C, and the residence time can be set to 1h. This time is the laboratory high temperature furnace simulation experiment time.

[0049] The specific operation process of the rapid cooling is: rapid cooling by a grate cooler, and the rapid cooling rate is 18-20°C / min, such as 20°C / min.

[0050] The heavy metal-containing wastes in the present invention refer to wastes containing heavy metals such as Pb, Cu, Cd, Zn, Ni, Cr, Mn, Hg, etc., including incineration fly ash, contaminated soil, electronic waste, sludge, printing and dyeing waste residues, and metal smelting slag, etc. In the embodiments of the present invention, semi-volatile heavy metals (Cd, Pb, Zn) are used as examples for effect verification.

[0051] The raw materials used in the following examples and comparative examples of the present invention are as follows:

[0052] Mineralization components: CaF2 is introduced from fluorite, wherein the CaF2 content is 50-70wt%; SrO is introduced from low-iron strontium slag, wherein the SrO content in the low-iron strontium slag is 30-70wt%; ZnO is introduced from smithsonite, wherein the ZnO content is 40-75wt%; MgO is introduced from magnesium smelting slag, wherein the MgO content is 6-10%.

[0053] Heavy metal adsorption components: attapulgite; bauxite; calcium oxide as quicklime.

[0054] High temperature resistant components: Alumina is the chemical reagent; fly ash is the first-class fly ash taken from the thermal power plant.

[0055] The "room temperature" in the present invention refers to 20-30°C unless otherwise specified.

[0056] The "parts" described in the present invention, unless otherwise specified, refer to parts by mass.

[0057] The raw materials used in the present invention are all purchased from the market.

[0058] The technical solution of the present invention is further illustrated by the following embodiments.

[0059] Examples 1-3, Comparative Examples 1-2

[0060] A composite functional additive suitable for cement kiln co-disposal of heavy metal-containing waste, comprising the following components by weight: 30-50 parts of a mineralization component, 35-50 parts of a heavy metal adsorption component and 15-20 parts of a high temperature resistant component;

[0061] in,

[0062] The mineralized components include the following raw materials: CaF2 0.5-0.8 parts, SrO 0.1-0.2 parts, ZnO 0.05-0.1 parts and MgO 0.05-0.2 parts;

[0063] The heavy metal adsorption component comprises the following raw materials: 0.4-0.6 parts of attapulgite, 0.2-0.3 parts of bauxite and 0.2-0.3 parts of calcium oxide;

[0064] The high temperature resistant component comprises the following raw materials: 0.3-0.5 parts of aluminum oxide and 0.5-0.7 parts of fly ash.

[0065] The preparation method of a composite functional additive for cement kiln co-disposal of heavy metal-containing wastes comprises the following steps: weighing a mineralization component, a heavy metal adsorption component and a high temperature resistant component according to the mass ratio in Table 1, mixing them evenly, and obtaining a composite functional additive.

[0066] Table 1 Example and Comparative Example Proportions (parts by mass)

[0067]

[0068]

[0069] Comparative Example 3

[0070] The same as Example 2, except that 50 parts of the fixed mineralization components are composed of 40 parts of CaF2 and 10 parts of CaSO4, that is, in the 50 parts of the mineralization components, the proportions of CaF2 and CaSO4 are 0.8 parts and 0.2 parts respectively.

[0071] Comparative Example 4

[0072] Same as Example 2, except that the mass of bauxite in the heavy metal adsorption component is replaced by kaolin.

[0073] Comparative Example 5

[0074] Same as Example 2, except that 15 parts of high temperature resistant components are composed of the following components: 5 parts of aluminum oxide, 5 parts of fly ash, and 5 parts of magnesium oxide.

[0075] Application Example 1

[0076] In the process of mixing cement raw materials (75wt% of lime, 12wt% of clay, 3wt% of correction raw materials, and 5wt% of contaminated soil solid waste), 0.5% of the composite functional additive prepared in Example 1 was added to the cement raw materials, and then pre-decomposed (heated to 800°C by a multi-stage cyclone preheating system, the preheated raw materials entered a high-temperature decomposition furnace, the decomposition furnace temperature was controlled at 850°C, and the material residence time was 1.2h), calcined (calcined at 1350°C for 1h), and rapidly cooled (cooling rate was 20°C / min) to obtain cement clinker.

[0077] Application Example 2

[0078] The same as Application Example 1, except that 1% by weight of cement raw material is added into the composite functional additive prepared in Example 2.

[0079] Application Example 3

[0080] The same as Application Example 1, except that 0.8% by weight of cement raw material is added into the composite functional additive prepared in Example 3.

[0081] Control group

[0082] Same as Application Example 1, except that no composite functional additive is added.

[0083] Comparative application example 1

[0084] The same as Application Example 2, except that 1% by weight of cement raw material is added to the additive prepared in Comparative Example 1.

[0085] Comparative Application Example 2

[0086] The same as Application Example 2, except that 1% by weight of cement raw material is added to the additive prepared in Comparative Example 2.

[0087] Comparative Application Example 3

[0088] The same as Application Example 2, except that 1% by weight of cement raw material is added to the additive prepared in Comparative Example 3.

[0089] Comparative Application Example 4

[0090] The same as Application Example 2, except that 1% by weight of cement raw material is added to the additive prepared in Comparative Example 4.

[0091] Comparative Application Example 5

[0092] The same as Application Example 2, except that 1% by weight of cement raw material is added to the additive prepared in Comparative Example 5.

[0093] The heavy metal solidification rate and compressive and flexural strengths of the cement clinkers (as adsorbents) prepared in the above application examples 1-3, the control group and comparative application examples 1-5 were tested, wherein the test method of the heavy metal solidification rate is as follows:

[0094] use Figure 1The calcination test device shown in the figure sets a heating program of 800℃-1200℃-1450℃, and the heating rate is 20℃ / min. The corundum crucible containing adsorbent and heavy metals accounting for 0.5% of the mass of the adsorbent (three components of PbO / CdO / ZnO are tested separately) is slowly pushed from one end of the tubular furnace tube into the furnace tube for calcination. The furnace door is closed and the gas cylinder valve is opened at the same time to realize the air flow in the furnace tube, and the air flow rate is controlled to be 1L / min by a float flowmeter. The tail end of the furnace tube is connected to three tail gas absorption bottles through a high-temperature resistant silicone hose. Two of the tail gas absorption bottles are filled with 250mL of 5% (mass concentration) HNO3 and 20% (volume concentration) H2O2 mixed absorption liquid, and one tail gas absorption bottle is filled with silica gel desiccant for the absorption of heavy metals in the tail gas. After the calcination experiment is completed, the crucible containing the sample is taken out and rapidly cooled to room temperature with a fan. The calcined material was digested by HNO3-HCl-HF-H2O2 method and then the heavy metal content was determined by ICP-MS. The results are shown in Table 2.

[0095] The calculation formula of the solidification rate of heavy metals by adsorbent is as follows:

[0096]

[0097] Where: R: solidification rate of heavy metals in adsorbent (100%);

[0098] K: content of heavy metals in the sample after calcination (mg / kg);

[0099] S: content of heavy metals in the sample before calcination (mg / kg);

[0100] LOI: Loss on ignition of a sample (%).

[0101] Table 2 Characteristics of cement clinker

[0102]

[0103] It can be seen from Table 2 that, compared with the control group without adding additives, the composite functional additives prepared in Examples 1-3 of the present invention can achieve efficient solidification of heavy metals in cement kiln co-processed clinker, and can increase the 28d compressive strength of the clinker by 1.26-3.98 MPa.

[0104] The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A composite functional additive suitable for cement kiln co-disposal of heavy metal-containing waste, characterized in that: Calculated by weight, the composition includes: 30-50 parts of mineralization component, 30-50 parts of heavy metal adsorption component and 10-20 parts of high temperature resistant component.

2. The composite functional additive suitable for cement kiln coordinated disposal of heavy metal-containing waste according to claim 1, characterized in that: The mineralized components include the following raw materials in parts by mass: 0.5-0.8 parts of CaF2, 0.1-0.2 parts of SrO, 0.05-0.2 parts of ZnO and 0.05-0.2 parts of MgO.

3. The composite functional additive suitable for cement kiln coordinated disposal of heavy metal-containing waste according to claim 1, characterized in that: Calculated by weight, the heavy metal adsorption component includes the following raw materials: 0.4-0.6 parts of attapulgite, 0.2-0.3 parts of bauxite and 0.2-0.3 parts of calcium oxide.

4. The composite functional additive suitable for cement kiln coordinated disposal of heavy metal-containing waste according to claim 1, characterized in that: Calculated by weight, the high temperature resistant component includes the following raw materials: 0.3-0.5 parts of aluminum oxide and 0.5-0.7 parts of fly ash.

5. A method for preparing a composite functional additive for cement kiln coordinated disposal of heavy metal-containing wastes according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: weighing a mineralization component, a heavy metal adsorption component and a high temperature resistant component according to a mass ratio, mixing them evenly, and obtaining a composite functional additive.

6. Use of the composite functional additive for the coordinated disposal of heavy metal-containing wastes in cement kilns as claimed in any one of claims 1 to 4 in the field of coordinated disposal of heavy metal-containing wastes in cement kilns.

7. The use according to claim 6, characterized in that: In the process of mixing cement raw materials, 0.5-1% of the composite functional additive is added into the cement raw materials, and then pre-decomposition, calcination and rapid cooling are carried out to obtain cement clinker.

8. The use according to claim 7, characterized in that: The pre-decomposition step includes: preheating to 800° C. in a preheater; and then decomposing carbonate in a decomposition furnace, with the decomposition temperature being 820-900° C. and the time being 1-1.5 hours.

9. The use according to claim 7, characterized in that: The calcination conditions are: temperature 1350-1400° C., time 1-2 h.

10. The use according to claim 7, characterized in that: The rapid cooling condition is: the cooling rate is 18-20°C / min.

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