Method of preparing alkali-activated cement by stepwise calcination with sodium chloride

Patent metadata

Field	Value
Publication number	US-2024327282-A1
Application number	US-202418737912-A
Country	US
Kind code	A1
Filing date	Jun 7, 2024
Priority date	Feb 24, 2024
Publication date	Oct 3, 2024
Grant date	—

Abstract

A method of preparing alkali-activated cement by stepwise calcination with sodium chloride includes the following steps. (1) Sodium chloride, a silicate and a carbonate are mixed and finely ground to obtain a raw material powder. (2) The raw material powder is calcined sequentially at 850-1050° C. and 1240° C. or more, and cooled to obtain a clinker. (3) The clinker is mixed with at least one of sodium hydroxide and potassium hydroxide, and ground finely to produce a cement powder.

First claim

What is claimed is:

1 . A method of preparing an alkali-activated cement by stepwise calcination with sodium chloride, comprising:
(1) mixing a sodium chloride, a silicate and a carbonate followed by grinding to obtain a raw material powder; (2) sequentially subjecting the raw material powder to a first calcination at 850-1050° C., a second calcination at 1240° C. or more and cooling to obtain a clinker; and (3) mixing the clinker with an alkali to produce the alkali-activated cement, wherein the alkali is sodium hydroxide, potassium hydroxide or a combination thereof; wherein a mixture of the silicate and the carbonate is adapted to produce a residue comprising SiO 2 , Al 2 O 3 , CaO, and MgO after oxidative calcination at 950±25° C.; a total weight of SiO 2 , Al 2 O 3 , CaO, and MgO accounts for 90.0% or more by weight of the residue; SiO 2 accounts for 31.0-47.0% by weight of the residue; Al 2 O 3 accounts for 12.4-18.0% by weight of the residue; CaO accounts for 21.3-46.3% by weight of the residue; and MgO accounts for 0-16.2% by weight of the residue; in the step (1), the sodium chloride is 8.0-20.0% by weight of the residue; and in the step (3), a weight of the alkali is calculated as follows:
(a weight of NaOH+0.713×a weight of KOH)/a weight of the clinker=(0.5-3.0)%.

2 . The method of claim 1 , wherein in the step (1), the grinding is performed such that the raw material powder is capable of passing through an 80 μm square-hole sieve.

3 . The method of claim 1 , wherein in the step (2), the first calcination is performed for at least 1 hour.

4 . The method of claim 1 , wherein in the step (2), water vapor is injected at a flow rate of 80 g·min −1 ·m −2 or more during the first calcination.

5 . The method of claim 1 , wherein in the step (2), the second calcination is performed for at least 1 hour.

6 . The method of claim 1 , wherein in the step (2), the cooling is performed by water quenching or air blast cooling.

7 . The method of claim 1 , wherein the step (3) is performed through steps of:
grinding the clinker to obtain a clinker powder; dissolving the alkali in water to obtain an alkali solution; and mixing the clinker powder with the alkali solution to produce the alkali-activated cement for use.

8 . The method of claim 1 , wherein the step (3) further comprises:
grinding a mixture of the alkali and the clinker.

9 . The method of claim 1 , wherein in the step (2), a tail gas produced from the first calcination and the second calcination is collected and dissolved in water to obtain a tail gas-containing aqueous solution; and the tail gas-containing aqueous solution is processed to produce hydrochloric acid or recycle valuable metals.

10 . The method of claim 4 , wherein in the step (2), a tail gas produced from the first calcination and the second calcination is collected and dissolved in water to obtain a tail gas-containing aqueous solution; and the tail gas-containing aqueous solution is processed to produce hydrochloric acid or recycle valuable metals.

Assignees

• Univ Hunan Science & Technology
• Hunan Xiangchu Xianlu Environmental Protection Tech Co Ltd

Inventors

• Peng Meixun
• Zhao Qiming
• Zhang Yuanpeng
• Liu Wenwei
• Chen Meilin

Classifications

• C04B28/006

  containing mineral polymers, e.g. geopolymers of the Davidovits type · CPC title

• C04B12/00

  Cements not provided for in groups C04B7/00 - C04B11/00 · CPC title

• C04B22/04 Primary

  Metals, e.g. aluminium used as blowing agent · CPC title

• C04B2103/10

  Accelerators; Activators · CPC title

• C04B7/52

  Grinding {; After-treatment of ground cement} · CPC title