Method for preparing cementing material by sintering activation of coal gangue

Patent metadata

Field	Value
Publication number	US-2024067564-A1
Application number	US-202318240372-A
Country	US
Kind code	A1
Filing date	Aug 31, 2023
Priority date	Aug 31, 2022
Publication date	Feb 29, 2024
Grant date	—

Abstract

A method for preparing a cementing material by sintering and activating coal gangue is provided. The method includes the following steps: (1) crushing coarse-grained coal gangue to predetermined particle size; (2) fully and evenly mixing the crushed coal gangue, the composite additive and water according to a set proportion, and granulating the obtained mixture; (3) distributing, igniting and exhausting the granulated pellets in the sintering machine to obtain decarburized coal gangue sinter; (4) cooling the decarburized coal gangue sinter in a cooler; (5) crushing and finely grinding the cooled coal gangue sinter to obtain a coal gangue active mixture; and (6) mixing the coal gangue active admixture, the fly ash, the quicklime and the gypsum according to a predetermined ratio, and then carrying out injection moulding, mold removal and curing to obtain the coal gangue-based cementitious material.

First claim

What is claimed is:

1 . A method for preparing a cementitious material by a sintering activation of a coal gangue, comprising the following steps:
(1) a pretreatment: crushing a coarse-grained coal gangue to a predetermined particle size to obtain a crushed coal gangue; (2) batching, mixing and granulating: fully mixing the crushed coal gangue obtained in step (1), a composite additive, and water according to a set proportion to obtain a first resulting mixture and granulating the first resulting mixture to obtain granulated pellets; (3) a sintering activation: distributing, igniting and exhausting the granulated pellets obtained in step (2) in a sintering machine for the sintering activation to obtain a decarburized coal gangue sinter; (4) cooling: cooling the decarburized coal gangue sinter obtained in step (3) in a cooler to obtain a cooled coal gangue sinter; (5) crushing and grinding: crushing and finely grinding the cooled coal gangue sinter obtained in step (4) to obtain a coal gangue active admixture; (6) compounding: mixing the coal gangue active admixture obtained in step (5), a fly ash, a quicklime, and a gypsum according to a predetermined ratio to obtain a second resulting mixture, and then performing a mold injection, a mold removal, and a curing on the second resulting mixture to obtain a coal gangue-based cementitious material.

2 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein a fixed carbon content in the coarse-grained coal gangue of step (1) is 1.5%-5.5%.

3 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein in step (1), the coarse-grained coal gangue is crushed to −15 mm by a jaw crusher and then crushed to 8 mm by a roller crusher; subsequently, a high-pressure roller mill is configured for crushing until the crushed coal gangue with a particle size of 6.3 mm accounting for 65%-85% and the crushed coal gangue with a particle size of −0.5 mm accounting for 15%-25%; and
a working pressure is 2.0-6.0 MPa in the crushing of the high-pressure roller mill.

4 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein in step (2), a granulation is carried out by using a cylinder granulator, and a rotating speed of the cylinder granulator is 30-60 rpm, a granulation time is 2-4 min; a water content sprayed in a granulation process is 1%-2%, and a water content of the granulated pellets obtained is controlled at 6.5%-7.5%.

5 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein a sintering method in step (3) is a belt sintering;
in a distribution process of the belt sintering, a height of a material layer is controlled to be 500-2000 mm; a thickness of a bedding material is controlled to be 15-25 mm, and the coal gangue with a particle size of 15-20 mm is configured as the bedding material; in an ignition process of the belt sintering, an ignition time is 1-2 min; an ignition temperature is 1050-1150° C.; an ignition negative pressure is 4-6 KPa, a heat preservation temperature is 700-1000° C., a heat preservation time is 3-5 min, and a heat preservation negative pressure is 4-6 KPa; and in a sintering process of a belt draft, a sintering negative pressure is 10-18 KPa.

6 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein in step (4), a cooling method of the decarburized coal gangue sinter comprises one of a belt sintering machine cooling, an annular cooling, and a shaft furnace cooling.

7 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 6 , wherein a shaft furnace cooling device is adopted in a cooling process, and the shaft furnace cooling device comprises a shaft furnace body, and the shaft furnace cooling device further comprises a receiving system, a cooling system, and a discharging system sequentially arranged from a top to a bottom;
the receiving system comprises a storage tank and a vibrating feeder; the storage tank is arranged above the vibrating feeder and configured for feeding from above the vibrating feeder, and a bottom end of the vibrating feeder is provided with a chute; a head end of the chute is connected to the storage tank, and a tail end of the chute is communicated with the shaft furnace body; and the tail end of the chute is provided with a baffle, and a height of the baffle is 3-8 cm.

8 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 7 , wherein the shaft furnace cooling device adopts a step-by-step cooling mode, and the shaft furnace cooling device sequentially comprises a primary cooling unit and a secondary cooling unit from the top to the bottom;
the primary cooling unit comprises two groups of central hoods, wherein the central hoods are arranged up and down along a height direction, and each of the two groups of the central hoods is provided with an air outlet; the primary cooling unit also comprises two fans symmetrically arranged on both sides of the shaft furnace body, each of the two fans is connected to three cold air pipes and an air inlet regulating valve is arranged at a joint of the two fans and the three cold air pipes; wherein a first cold air pipe and a second cold air pipe of the three cold air pipes are connected to the two groups of the central hoods; a third cold air pipe of the three cold air pipes is arranged on a side of the shaft furnace body, and the side of the shaft furnace body is provided with a corresponding air outlet; a structure of the secondary cooling unit is consistent with a structure of the primary cooling unit; and an air supply system of the primary cooling unit is a dry-cooling blower with an air volume of 3,000-3,500 m/t, and the dry-cooling blower is configured to perform a first-stage cooling on the decarburized coal gangue sinter for rapidly cooling and forming a high-temperature waste gas; an air supply system of the secondary cooling unit is a normal temperature blower with an air volume of 1500-2000 m 3 /t, and the normal temperature blower is configured to perform a second-stage cooling on the decarburized coal gangue sinter and form a low-temperature waste gas.

9 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 1 , wherein in step (5), the cooled coal gangue sinter is crushed to −3 mm by a toothed roller crusher, and then a specific surface area of a crushed coal gangue sinter is increased to 500-700 m 2 /kg by combining a high-pressure roller mill and a ball mill to obtain a coal gangue active mixture with a set fineness and specific surface area;
in step (6), in raw materials of the coal gangue-based cementitious material, mass percentages of the coal gangue active admixture, the fly ash, the quicklime, and the gypsum are 55%-75%, 10%-20%, 10%-20%, and 5%-20%, respectively.

10 . The method for preparing the cementitious material by the sintering activation of the coal gangue according to claim 2 , wherein in step (1), the coarse-grained coal gangue is crushed to −15 mm by a jaw crusher and then crushed to 8 mm by a roller crusher; subsequently, a high-pressure roller mill is configured for crushing until the crushed coal gangue with a particle size of 6.3 mm accounting for 65%-85% and the crushed coal gangue with a particle size of −0.5 mm accounting for 15%-25%; and
a working pressure is 2.0-6.0 MPa in th

Assignees

• Univ Central South

Inventors

• Guo Zhengqi
• Pan Jian
• Zhu Deqing
• Yang Congcong
• Li Siwei
• Li Qihou

Classifications

• C04B18/12 Primary

  from quarries, mining or the like · CPC title

• C04B11/26

  {strating from chemical gypsum}; starting from phosphogypsum or from waste, e.g. purification products of smoke (C04B11/02 takes precedence; chemical purification of smoke, fumes or exhaust gases B01D53/00 {purification of gypsum C01F11/46}) · CPC title

• C04B20/026

  Comminuting, e.g. by grinding or breaking; Defibrillating fibres other than asbestos · CPC title

• C04B20/04

  Heat treatment · CPC title

• C04B28/12

  Hydraulic lime · CPC title