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

Abstract

The application discloses a composite functional additive suitable for cement kiln collaborative disposal of heavy metal-containing waste and belongs to the technical field of cement manufacturing. According to mass fractions, the composite functional additive comprises the following components: mineralization components 30-50 parts, heavy metal adsorption components 30-50 parts and high-temperature-resistant components 10-20 parts. The mineralization components comprise CaF2, SrO, ZnO and MgO; the heavy metal adsorption components comprise attapulgite, bauxite and calcium oxide; and the high-temperature-resistant components comprise aluminum oxide and fly ash. Through scientific research and practice test, the composite functional additive with heavy metal solidification and mineralization functions is successfully prepared, and the process safety of the cement kiln collaborative disposal of the heavy metal-containing waste and the clinker product quality can be improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cement manufacturing, and particularly relates to a composite functional additive suitable for cement kiln collaborative disposal of heavy metal-containing waste. BACKGROUND

[0002] Cement kiln collaborative disposal refers to using waste to replace raw materials and fuels in the production of cement clinker, taking the cement rotary kiln as a carrier, and realizing efficient and harmless disposal of solid waste through high-temperature incineration and cement clinker mineralization high-temperature sintering process. The disposal temperature is high (1450 DEG C), and the material residence time is long, so the cement kiln collaborative disposal can completely decompose dioxin and realize the stable solidification of heavy metals through the clinker mineralization process. Another significant advantage of the cement kiln collaborative disposal is that the waste is directly productized, solving the problem of secondary utilization of slag.

[0003] Waste generated by non-ferrous metal mining and dressing industry, smelting industry, lead storage battery manufacturing industry, leather and its products industry, chemical raw material and chemical product manufacturing industry, and electroplating industry is an important source of heavy metal pollution, and contains heavy metals mainly including Pb, Cu, Cd, Zn, Ni, Cr, Mn, Hg, etc. According to the volatilization degree of heavy metals at high temperature, 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 temperature, and are stably solidified in slag; however, volatile heavy metals and most semi-volatile heavy metals are converted into gas at high temperature and are easily attached to fly ash, and this problem exists in incineration and cement kiln collaborative disposal processes, which has attracted the attention of many scholars at home and abroad. In addition, solidification of heavy metals in clinker may lead to a decrease in the content of C3S mineral phase in clinker, an increase in the content of C2S phase and f-CaO, and thus an adverse effect on the strength of clinker. In summary, the utilization of cement kiln collaborative disposal of heavy metal-containing waste is faced with the problems of low heavy metal solidification rate, enrichment of heavy metals in the kiln, equipment safety hazards, and reduction of clinker strength and influence on clinker quality. SUMMARY

[0004] In view of the above technical problems, the application provides a composite functional additive suitable for cement kiln collaborative disposal of heavy metal-containing waste, which can improve the process safety of cement kiln collaborative disposal of heavy metal-containing waste and the quality of clinker products.

[0005] To achieve the above object, the application provides the following technical scheme.

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

[0007] The composite functional adsorbent provided by the present application 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 a cement kiln and inhibit the volatilization and condensation of heavy metals; further, the mineralization component can promote the decomposition of calcium carbonate, reduce the clinker sintering temperature by about 50-100 DEG C, promote the formation of tricalcium silicate minerals and improve the strength and cementitious property of clinker; in addition, the mineralization component can also reduce the calcination temperature and play a role in reducing the volatilization of heavy metals, while the clay minerals and high-temperature-resistant minerals can improve the strength of clinker by increasing the Al / Si ratio of clinker minerals, and through the synergistic effect of multiple components, the volatilization and condensation of heavy metals are inhibited, the enrichment and discharge of heavy metals in the kiln are reduced, and the safety of the cement kiln co-processing heavy metal-containing waste process is effectively improved.

[0008] Further, the mineralization component comprises the following raw materials in parts by mass: CaF2 0.5-0.8 parts, SrO 0.1-0.2 parts, ZnO 0.05-0.2 parts and MgO 0.05-0.2 parts.

[0009] Further, the heavy metal adsorption component comprises the following raw materials in parts by mass: attapulgite 0.4-0.6 parts, bauxite 0.2-0.3 parts and calcium oxide 0.2-0.3 parts.

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

[0011] The second purpose of the present application is to provide a preparation method of a composite functional additive for cement kiln co-processing heavy metal-containing waste, which comprises the following steps: weighing the mineralization component, the heavy metal adsorption component and the high-temperature-resistant component according to the mass ratio, and mixing uniformly to obtain the composite functional additive.

[0012] The third purpose of the present application is to provide an application of the composite functional additive for cement kiln co-processing heavy metal-containing waste in the field of cement kiln co-processing heavy metal-containing waste.

[0013] Further, the composite functional additive is mixed into 0.5-1% of the mass of cement raw materials in the cement raw material batching process, and then pre-decomposition, calcination and quenching are carried out to obtain cement clinker.

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

[0015] The present application is prepared through scientific research and practice inspection, and successfully prepares the composite functional additive with heavy metal solidification and mineralization functions, which can improve the process safety of the cement kiln for co-processing the waste containing heavy metals and the clinker product quality.

[0016] The method has the advantages of easy raw materials, simple process steps, easy popularization and application, low cost, wide application, good economic benefit and social benefit. BRIEF DESCRIPTION OF DRAWINGS

[0017] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and the illustrative embodiments of the present application and their description serve the purpose of explaining the present application. The present application is not limited by the accompanying drawings.

[0018] Figure 1 It is a calcination experimental device of the present application. DETAILED DESCRIPTION

[0019] The various illustrative embodiments of the present application will now be described in detail below. This detailed description is merely intended to teach a person skilled in the art further about some aspects, characteristics and embodiments of the present application, and should not be considered as a limitation of the present application.

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

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are cited. In the case of conflict between any document incorporated by reference and the present specification, the present specification will control.

[0022] Many modifications and variations of the present application specification can be made without departing from the scope or spirit of the present application, which will be apparent to those skilled in the art. Other embodiments resulting from the present specification will be apparent to those skilled in the art. The present specification and examples are only exemplary.

[0023] As used herein, the terms "comprises", "comprising", "includes", "including", "has", "having", "contains", "containing", or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises, includes, has, contains a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0024] The composite functional additive for cement kiln co-processing heavy metal-containing waste provided by the embodiments of the present application comprises, in mass fraction, 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] For example, in the following preferred embodiments of the present application:

[0026] The mineralization component comprises 30 parts, 40 parts, 50 parts, or any range or sub-range between the aforementioned ratios in the composite functional additive;

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

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

[0029] In some possible embodiments, the mineralization component comprises, in mass fraction, the following raw materials: CaF2 0.5-0.8 parts, SrO 0.1-0.2 parts, ZnO 0.05-0.2 parts, and MgO 0.05-0.2 parts.

[0030] For example, in the following preferred embodiments of the present application:

[0031] The CaF2 comprises 0.5 parts, 0.7 parts, 0.8 parts, or any range or sub-range between the aforementioned ratios in the mineralization component;

[0032] The SrO comprises 0.1 parts, 0.15 parts, 0.2 parts, or any range or sub-range between the aforementioned ratios in the mineralization component;

[0033] The ZnO comprises 0.05 parts, 0.1 parts, or any range or sub-range between the aforementioned ratios in the mineralization component;

[0034] The MgO comprises 0.05 parts, 0.2 parts, or any range or sub-range between the aforementioned ratios in the mineralization component.

[0035] In some possible embodiments, the heavy metal adsorption component comprises, in mass fraction, the following raw materials: attapulgite 0.4-0.6 parts, bauxite 0.2-0.3 parts, and calcium oxide 0.2-0.3 parts.

[0036] For example, in the following preferred embodiments of the present application:

[0037] The heavy metal adsorption component contains 0.4 parts, 0.5 parts, 0.6 parts or any range or sub-range between the foregoing ratios of attapulgite;

[0038] The heavy metal adsorption component contains 0.2 parts, 0.25 parts, 0.3 parts or any range or sub-range between the foregoing ratios of bauxite;

[0039] The heavy metal adsorption component contains 0.2 parts, 0.25 parts, 0.3 parts or any range or sub-range between the foregoing ratios of calcium oxide.

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

[0041] Exemplarily, in the following preferred embodiments of the present application:

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

[0043] The high-temperature-resistant component contains 0.5 parts, 0.6 parts, 0.7 parts or any range or sub-range between the foregoing ratios of fly ash.

[0044] The preparation method of the composite functional additive for cement kiln co-processing of heavy metal-containing waste includes the following steps: taking the mineralization component, the heavy metal adsorption component and the high-temperature-resistant component by mass ratio, mixing uniformly to obtain the composite functional additive.

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

[0046] In some feasible embodiments, the composite functional additive is incorporated in an amount of 0.5-1% of the mass of the cement raw material during the cement raw material batching process, and then pre-decomposition, calcination and quenching are performed to obtain cement clinker. Exemplarily, in the following preferred embodiments of the present application, the incorporation amount of the composite functional additive can be selected as 0.5%, 0.8% or 1%.

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

[0048] The calcining condition is: temperature 1350-1400℃, time 1-2h. Exemplarily, in the following preferred embodiments of the present application, the calcining temperature can be set as 1350℃, and the residence time can be set as 1h. The time is the laboratory high-temperature furnace simulation experiment time.

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

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

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

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

[0053] Heavy metal adsorption component: attapulgite; bauxite; calcium oxide is quicklime.

[0054] High-temperature resistant component: aluminum oxide is a chemical reagent; fly ash is first-stage fly ash taken from a thermal power plant.

[0055] The "room temperature" in the present application refers to 20-30℃, unless otherwise specified.

[0056] The "part" in the present application refers to mass part, unless otherwise specified.

[0057] The raw materials used in the present application are all obtained by purchase on the market.

[0058] The technical solutions of the present application are further illustrated by the following examples.

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

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

[0061] Among them,

[0062] The mineralization component comprises 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: attapulgite 0.4-0.6 parts, bauxite 0.2-0.3 parts, and calcium oxide 0.2-0.3 parts;

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

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

[0066] Table 1: mixing ratio (mass parts) of examples and comparative examples

[0067]

[0068]

[0069] Comparative Example 3

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

[0071] Comparative Example 4

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

[0073] Comparative Example 5

[0074] The same as Example 2, except that the 15 parts of the high-temperature-resistant component is 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] The composite functional additive prepared in Example 1 is mixed into cement raw material with a mass of 0.5% during the cement raw material batching process (limestone 75wt%, clay 12wt%, correction raw material 3wt%, and contaminated soil solid waste 5wt%), and then pre-decomposition (heated to 800℃ by a multi-stage cyclone preheating system, the preheated raw material enters a high-temperature decomposition furnace, the decomposition furnace temperature is controlled at 850℃, and the material residence time is 1.2h), calcination (calcined at 1350℃ for 1h), and rapid cooling (cooling rate of 20℃ / min) are performed to obtain cement clinker.

[0077] Application Example 2

[0078] The same as Application Example 1, except that the composite functional additive prepared in Example 2 is incorporated at a mass of 1% of the cement raw material.

[0079] Application Example 3

[0080] The same as Application Example 1, except that the composite functional additive prepared in Example 3 is incorporated at a mass of 0.8% of the cement raw material.

[0081] Control Group

[0082] The same as Application Example 1, except that no composite functional additive is incorporated.

[0083] Comparative Application Example 1

[0084] The same as Application Example 2, except that the additive prepared in Comparative Example 1 is incorporated at a mass of 1% of the cement raw material.

[0085] Comparative Application Example 2

[0086] The same as Application Example 2, except that the additive prepared in Comparative Example 2 is incorporated at a mass of 1% of the cement raw material.

[0087] Comparative Application Example 3

[0088] The same as Application Example 2, except that the additive prepared in Comparative Example 3 is incorporated at a mass of 1% of the cement raw material.

[0089] Comparative Application Example 4

[0090] The same as Application Example 2, except that the additive prepared in Comparative Example 4 is incorporated at a mass of 1% of the cement raw material.

[0091] Comparative Application Example 5

[0092] The same as Application Example 2, except that the additive prepared in Comparative Example 5 is incorporated at a mass of 1% of the cement raw material.

[0093] The heavy metal solidification rate and the compressive and flexural strengths of the cement clinkers prepared in the above Application Examples 1-3, the control group, and the comparative application examples 1-5 (as adsorbents) were measured, wherein the heavy metal solidification rate was measured by the following method:

[0094] Using Figure 1The calcination experimental device is shown, and the temperature increasing procedure of 800℃-1200℃-1450℃ is set, and the temperature increasing rate is 20℃ / min. The corundum crucible containing the adsorbent and 0.5% of the heavy metal (PbO / CdO / ZnO three components are respectively tested) in the mass of the adsorbent is slowly pushed into the furnace tube from one end of the tube furnace tube to be calcined. The air valve of the gas cylinder is opened at the same time to realize the air flow in the furnace tube, and the flow rate is controlled to be 1L / min by using the float flowmeter. The tail end of the tail of the furnace tube is connected with three tail gas absorption bottles through high-temperature resistant silica gel hoses. 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 of the tail gas absorption bottles is filled with silica gel desiccant for absorbing the heavy metal in the tail gas. After the calcination experiment is completed, the crucible containing the sample is taken out and cooled to room temperature by using a fan. The heavy metal content is measured by using ICP-MS after the calcined material is digested by using the HNO3-HCl-HF-H2O2 method. The results are shown in Table 2.

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

[0096]

[0097] In the formula, R: the solidification rate of the heavy metal in the adsorbent (100%);

[0098] K: the content of the heavy metal in the calcined sample (mg / kg);

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

[0100] LOI: the loss on ignition of the sample (%).

[0101] Table 2 Properties of cement clinker

[0102]

[0103] As can be seen from Table 2, compared with the control group without adding the additive, the composite functional additive prepared in Examples 1-3 of the present application can realize the efficient solidification of the heavy metal in the cement kiln co-processing clinker, and can make the 28d compressive strength of the clinker increase by 1.26-3.98MPa.

[0104] The above is only the preferred specific embodiment of the present application, but the protection scope of the present application is not limited to this, and any change or replacement easily thought of by those skilled in the art within the technical range disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A composite functional additive suitable for co-processing heavy metal-containing waste in cement kilns, characterized in that, Based on mass fractions, it includes the following components: 30-50 parts mineralization component, 30-50 parts heavy metal adsorption component, and 10-20 parts high temperature resistant component; The mineralization components include the following raw materials: 0.5-0.8 parts CaF2, 0.1-0.2 parts SrO, 0.05-0.2 parts ZnO and 0.05-0.2 parts MgO; 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; The high-temperature resistant component includes the following raw materials: 0.3-0.5 parts alumina and 0.5-0.7 parts fly ash.

2. A method for preparing a composite functional additive for co-processing heavy metal-containing waste in cement kilns as described in claim 1, characterized in that, The process includes the following steps: weighing the mineralization component, heavy metal adsorption component, and high-temperature resistant component according to the mass ratio, mixing them evenly, and obtaining a composite functional additive.

3. The application of the composite functional additive as described in claim 1 for co-processing heavy metal-containing waste in cement kilns in the field of co-processing heavy metal-containing waste in cement kilns.

4. The application according to claim 3, characterized in that, During the cement raw meal batching process, 0.5-1% of the mass of the cement raw meal is added to a composite functional additive, followed by pre-decomposition, calcination, and rapid cooling to obtain cement clinker.

5. The application according to claim 4, characterized in that, The pre-decomposition step includes: preheating to 800°C using a preheater; and then decomposing the carbonates in a decomposition furnace at a temperature of 820-900°C for 1-1.5 hours.

6. The application according to claim 4, characterized in that, The calcination conditions are: temperature 1350-1400℃, time 1-2h.

7. The application according to claim 4, characterized in that, The conditions for rapid cooling are: a cooling rate of 18-20℃ / min.

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