Non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, foaming, preparation method therefor and use thereof

Abstract

A non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming, and a preparation method therefor and use thereof. The non-sintered high-strength lightweight aggregate is prepared from a sulfur-based solid waste, an alkaline-based solid waste, an auxiliary cementing material, a ferro-aluminum-sulfur cementing material, water, and a foaming agent as raw materials. Based on the mass of the total solid, the total content of the sulfur-based solid waste, the alkaline-based solid waste, and the auxiliary cementing material is 80-90 wt %, and the content of the ferro-aluminum-sulfur cementing material is 10-20 wt %. The mass ratio of the water to the total solid is (15-20):(80-85). The foaming agent accounts for 0.3-0.7% of the mass of the total solid. The mass ratio between the sulfur-based solid waste, the alkaline-based solid waste, and the auxiliary cementing material is (27-33):(27-33):(18-25).

Claims

1. A non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming, comprising a sulfur-based solid waste, an alkaline-based solid waste, an auxiliary cementing material, a ferro-aluminum-sulfur cementing material, water, and a foaming agent, wherein based on the mass of the total solid, the total content of the sulfur-based solid waste, the alkaline-based solid waste, and the auxiliary cementing material in percentage by mass is 80%-90%, and the content of the ferro-aluminum-sulfur cementing material in percentage by mass is 10%-20%; the mass ratio of the water to the total solid is (15-20):(80-85); the foaming agent accounts for 0.3%-0.7% of the mass of the total solid; the mass ratio between the sulfur-based solid waste, the alkaline-based solid waste, and the auxiliary cementing material is (27-33):(27-33):(18-25); and a method for preparing the non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming comprises: step one: first stirring and uniformly mixing the sulfur-based solid waste, the alkaline-based solid waste, the auxiliary cementing material, and the ferro-aluminum-sulfur cementing material, adding the foaming agent and the water, and second stirring and granulating the mixture to obtain lightweight aggregate spheres, wherein the sulfur-based solid waste, the alkaline-based solid waste, the auxiliary cementing material, and the ferro-aluminum-sulfur cementing material are mixed in a stirring granulator; the first stirring is high-speed stirring performed at 50 Hz for 1-5 min; and the second stirring is medium-speed stirring performed at 25 Hz for 5-25 min; and step two: curing the lightweight aggregate spheres and screening the cured lightweight aggregate spheres to obtain the non-sintered high-strength lightweight aggregate, wherein the non-sintered high-strength lightweight aggregate has a 28 d cylindrical compress strength of higher than or equal to 10 MPa and a bulk density of less than 1,000 kg/m.sup.3.

2. The non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming according to claim 1, wherein the sulfur-based solid waste comprises desulfurized gypsum, phosphogypsum, and titanium gypsum; and the sulfur-based solid waste has a SO.sub.3 content of higher than or equal to 40 wt % and an average particle size of less than or equal to 50 ?m.

3. The non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming according to claim 1, wherein the alkaline-based solid waste comprises red mud, steel slag, and an alkaline residue; and a leaching solution of the alkaline-based solid waste has a pH of higher than 10 and an average particle size of less than or equal to 50 ?m.

4. The non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming according to claim 1, wherein the auxiliary cementing material comprises mineral waste powder, fly ash, and silica fume; or the ferro-aluminum-sulfur cementing material comprises a phosphogypsum-based cementing material, wherein in the ferro-aluminum-sulfur cementing material, the content of CaO is lower than 40 wt %, the content of Fe.sub.2O.sub.3 is higher than 5 wt %, and the content of SO.sub.3 is lower than 15 wt %.

5. The non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming according to claim 1, wherein the foaming agent comprises H.sub.2O.sub.2 and aluminum powder.

6. A method for preparing the non-sintered high-strength lightweight aggregate prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming according to claim 1, comprising: step one: stirring and uniformly mixing the sulfur-based solid waste, the alkaline-based solid waste, the auxiliary cementing material, and the ferro-aluminum-sulfur cementing material, adding the foaming agent and the water, and stirring and granulating the mixture to obtain lightweight aggregate spheres, wherein the sulfur-based solid waste, the alkaline-based solid waste, the auxiliary cementing material, and the ferro-aluminum-sulfur cementing material are mixed in a stirring granulator; the first stirring is high-speed stirring performed at 50 Hz for 1-5 min; and the second stirring is medium-speed stirring performed at 25 Hz for 5-25 min; and step two: curing the lightweight aggregate spheres and screening the cured lightweight aggregate spheres to obtain the non-sintered high-strength lightweight aggregate.

7. The method according to claim 6, wherein the particle size of the lightweight aggregate spheres is 1-20 mm.

8. The method according to claim 6, wherein in the step two, the curing comprises: curing at a temperature of 25-35? C. and a humidity of 92%-98% for 0-5 days, followed by natural curing for 1-5 days with the lightweight aggregate spheres being regularly sprayed with water and slightly turned over once every day.

Description

DETAILED DESCRIPTION

(1) To facilitate understanding of the present disclosure, the following examples are set forth in the present disclosure. Those skilled in the art should understand that the examples only help understand the present disclosure and should not be construed as specific limitations to the present disclosure.

(2) In the following examples and comparative examples, the sulfur-based solid waste used had a SO.sub.2 content of 42.67% and an average particle size of less than or equal to 50 ?m; a leaching solution of the alkaline-based solid waste had a pH of 11.5 and the alkaline-based solid waste had an average particle size of less than or equal to 50 ?m; the ferro-aluminum-sulfur cementing material was a phosphogypsum-based cementing material, wherein the content of CaO was 34.79%, the content of Fe.sub.2O.sub.3 was 9.32%, and the content of SO; was 13.60%; and the foaming agent was H.sub.2O.sub.2.

(3) In the following examples, the obtained non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming had a 28 d cylindrical compress strength of higher than or equal to 10 MPa and a bulk density of less than 1,000 kg/m.sup.3. But the lightweight aggregates for the comparative examples failed to reach the 28 d cylindrical compress strength of higher than or equal to 10 MPa and the bulk density of less than 1,000 kg/m.sup.3 at the same time.

Example 1

(4) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming was provided, including the following steps.

(5) In step one, 82 wt % of phosphogypsum, red mud, and mineral slag powder at a mass ratio of 30:30:22 and 18 wt % of a phosphogypsum-based cementing material were used as raw materials and strongly stirred and premixed in a stirring granulator at a high speed (50 Hz) for 3 min.

(6) In step two, 16 wt % of water containing 0.5% of H.sub.2O.sub.2 was uniformly added and the mixture was stirred at a medium speed (25 Hz) for 6 min.

(7) In step three, the cylinder of the stirring granulator was turned over to discharge the obtained lightweight aggregate spheres to a container;

(8) In step four, the discharged lightweight aggregate spheres were screened.

(9) In step five, the screened lightweight aggregate spheres were transferred into a curing room for curing. The curing includes: curing at a temperature of 28? C. and a humidity of 98% for 1 day, followed by natural curing for 3 days with the lightweight aggregate spheres being regularly sprayed with water and slightly turned over once every day.

(10) The non-sintered high-strength lightweight aggregate product one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming in this example had a 1 d cylindrical compress strength of 4.2 MPa, the 7 d cylindrical compress strength of 6.0 MPa, the 28 d cylindrical compress strength of 10.5 MPa, a bulk density of 780 kg/m.sup.3, a water absorption rate of 9.5%, and a softening coefficient of 0.86.

Example 2

(11) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming was provided, which was different from Example 1 in that the phosphogypsum was replaced by desulfurized gypsum.

(12) The non-sintered high-strength lightweight aggregate product one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming in this example had a 1 d cylindrical compress strength of 4.5 MPa, a 7 d cylindrical compress strength of 6.8 MPa, a 28 d cylindrical compress strength of 11.2 MPa, a bulk density of 950 kg/m.sup.3, a water absorption rate of 7.5%, and a softening coefficient of 0.88.

(13) The strength and bulk density of the non-sintered lightweight aggregate prepared using desulfurized gypsum in this example were both slightly higher than those of the lightweight aggregate prepared using phosphogypsum (i.e., the lightweight aggregate prepared in Example 1). This may be due to the effect of phosphorus in phosphogypsum.

Example 3

(14) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming was provided, which was different from that in Example 1 in that the red mud was replaced by acetylene sludge.

(15) The non-sintered high-strength lightweight aggregate product one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming in this example had a 1 d cylindrical compress strength of 4.3 MPa, a 7 d cylindrical compress strength of 6.5 MPa, a 28 d cylindrical compress strength of 10.8 MPa, a bulk density of 930 kg/m.sup.3, a water absorption rate of 6.5%, and a softening coefficient of 0.89.

Comparative Example 1

(16) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming was provided, which was different from Example 1 in that: in step one, 85 wt % of phosphogypsum, red mud, and mineral slag powder, and 15 wt % of a phosphogypsum-based cementing material were used as raw materials, and no foaming agent was added.

(17) The non-sintered high-strength lightweight aggregate product one-shot prepared from sulfur-based and alkaline-based solid wastes by stirring, granulation, and foaming in this example had a 3 d cylindrical compress strength of 6.0 MPa, a 7 dcylindrical compress strength of 9.3 MPa, a 28 dcylindrical compress strength of 14.8 MPa, a bulk density of 1,100 kg/m.sup.3, a water absorption rate of 3.8%, and a softening coefficient of 0.96.

(18) The increase in the cylindrical compress strength and bulk density were due to the following two reasons: (1) The alkali-sulfur double excitation effect was enhanced by increasing the amount of alkaline-based and sulfur-based solid wastes added, the hydration reaction took place more thoroughly, thereby increasing the mineral content in the system and improving the strength performance. (2) The non-sintered lightweight aggregate product prepared without using the foaming agent had no pore structures distributed therein, and therefore had a more compact structure with increased strength performance and bulk density.

Comparative Example 2

(19) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from a sulfur-based solid waste by stirring, granulation, and foaming was provided, which was different from Example 1 in that: the red mud component was all replaced by phosphogypsum.

(20) The sulfur-based solid waste stirred, granulated, foamed and once-formed non-sintered high-strength lightweight aggregate product in this example had a 3 d cylindrical compress strength of 3.5 MPa, a 7 d cylindrical compress strength of 4.8 MPa, a 28 d cylindrical compress strength of 8.5 MPa, a bulk density of 830 kg/m.sup.3, a water absorption rate of 6.9%, and a softening coefficient of 0.83.

Comparative Example 3

(21) A method for preparing a non-sintered high-strength lightweight aggregate one-shot prepared from an alkaline-based solid waste by stirring, granulation, and foaming was provided, which was different from Example 1 in that: the phosphogypsum component was all replaced by red mud.

(22) The alkaline-based solid waste stirred, granulated, foamed and once-formed non-sintered high-strength lightweight aggregate product in this example had a cylindrical compress strength of 9.1 MPa, a bulk density of 890 kg/m.sup.3, a water absorption rate of 10.9%, and a softening coefficient of 0.83.

Comparative Example 4

(23) A method for preparing a non-sintered high-strength lightweight aggregate one-shot from sulfur-based and alkaline-based solid wastes was provided, which was different from Example 1 in that: a disc granulator was used for granulation and the process integrating stirring and granulation was not used.

(24) The non-sintered high-strength lightweight aggregate product in the example had a 3 d cylindrical compress strength of 3.1 MPa, a 7 d cylindrical compress strength of 4.9 MPa, a 28 d cylindrical compress strength of 7.6 MPa, a bulk density of 900 kg/m.sup.3, a water absorption rate of 10.3%, and a softening coefficient of 0.80.

(25) It should be understood that although the detailed process equipment and process flow of the present disclosure are illustrated through the above examples, the present disclosure is not limited thereto, i.e., it is not intended that the present disclosure must be implemented by relying on the detailed process equipment and process flow. Those skilled in the art should understand that any improvement to the present disclosure, equivalent replacement of the raw materials of the product of the present disclosure, addition of auxiliary components, selection of specific methods and the like shall all fall within the scope of protection of the present disclosure.