Method for preparing non-sintered shell-wrapped ceramsite using solid waste meanwhile immobilizing heavy metal in river sediment, and non-sintered river-sediment-based ceramsite

Patent metadata

Field	Value
Publication number	US-12221379-B2
Application number	US-202418633658-A
Country	US
Kind code	B2
Filing date	Apr 12, 2024
Priority date	Apr 14, 2023
Publication date	Feb 11, 2025
Grant date	Feb 11, 2025

Abstract

Disclosed are a method for preparing a non-sintered shell-wrapped ceramsite using solid waste meanwhile immobilizing a heavy metal in river sediment, and a non-sintered river-sediment-based shell-wrapped ceramsite, which relate to the technical field of building materials. The disclosure combines river sediment with a solid waste powder and an alkali activating powder material, and adopts multiple-step granulations to realize particle size control and physical pore formation, thereby obtaining a non-sintered ceramsite. A sulfoaluminate cement and a Portland cement are used to encapsulate the non-sintered ceramsite and form a shell by wrapping, thereby preparing a non-sintered river-sediment-based shell-wrapped ceramsite with internal porosity and dense shell.

First claim

What is claimed is:

1. A method for preparing a non-sintered river-sediment-based shell-wrapped ceramsite using solid waste meanwhile immobilizing a heavy metal in river sediment, comprising the steps of:
(1) dehydrating the river sediment and compacting to obtain a dry cake-shaped residual soil, and grinding the dry cake-shaped residual soil, to obtain a dry powdery residual soil;
(2) mixing the dry powdery residual soil with a solid waste powder and an alkali activating powder material, to obtain a mixture;
(3) subjecting the mixture to a first granulation, to obtain first grade cold-bonded ceramsites;
(4) sieving the first grade cold-bonded ceramsites to obtain first grade cold-bonded ceramsites having a particle size of not less than 1 mm and not more than 3 mm, and first grade cold-bonded ceramsites having a particle size of larger than 3 mm but not more than 5 mm, and performing a second granulation on the first grade cold-bonded ceramsites having a particle size of not less than 1 mm and not more than 3 mm, and the first grade cold-bonded ceramsites having a particle size of larger than 3 mm but not more than 5 mm, to obtain second grade cold-bonded ceramsites, wherein a mass ratio of the first grade cold-bonded ceramsites having a particle size of not less than 1 mm and not more than 3 mm to the first grade cold-bonded ceramsites having a particle size of larger than 3 mm but not more than 5 mm is in a range of (2-1):(1-2); and
(5) mixing the second grade cold-bonded ceramsites with a sulfoaluminate cement and a Portland cement, and subjecting a resulting mixture to a third granulation, to obtain the non-sintered river-sediment-based shell-wrapped ceramsite,
wherein based on a total mass of the dry powdery residual soil, the solid waste powder, and the alkali activating powder material being 100%, a mass content of the dry powdery residual soil is in a range of 70-80%, a mass content of the solid waste powder is in a range of 15-25%, and a mass content of the alkali activating powder material is in a range of 5-10%;
an adhesive is added during the first granulation and the second granulation;
a mass ratio of the sulfoaluminate cement to the Portland cement is in a range of (7-9):(3-1); and
a mass ratio of the second grade cold-bonded ceramsites to the sulfoaluminate cement is in a range of 3:1 to 3:2.

2. The method as claimed in claim 1 , wherein the dry powdery residual soil has a particle size such that the dry powdery residual soil passes through a 180-mesh sieve.

3. The method as claimed in claim 1 , wherein the solid waste powder comprises fly ash, slag, steel slag, and red mud; and
based on a total mass of the dry powdery residual soil, the solid waste powder, and the alkali activating powder material being 100%, a mass content of the fly ash is in a range of 10-12%, a mass content of the slag is in a range of 3-5%, a mass content of the steel slag is in a range of 4-5%, and a mass content of the red mud is in a range of 2-3%.

4. The method as claimed in claim 1 , wherein the alkali activating powder material comprises quicklime, sodium silicate, sodium hydroxide, and gypsum; and
based on a total mass of the dry powdery residual soil, the solid waste powder, and the alkali activating powder material being 100%, a mass content of the quicklime is in a range of 2-3%, a mass content of the sodium silicate is in a range of 1-2%, a mass content of the sodium hydroxide is in a range of 1-3%, and a mass content of the gypsum is in a range of 1-2%.

5. The method as claimed in claim 1 , wherein the adhesive is a mixed solution of water glass and water, and
a mass concentration of the water glass in the adhesive is in a range of 5-10%, and the water glass has a modulus of 2.0.

Assignees

• Univ Shenzhen

Inventors

• Cui Hongzhi
• Zheng Dapeng
• Pang Qiangwei
• Jin Yu
• Fang Yuan

Classifications

• C04B2111/00732

  for soil stabilisation · CPC title

• C04B28/065

  Calcium aluminosulfate cements, e.g. cements hydrating into ettringite · CPC title

• C04B18/021 Primary

  agglomerated by a mineral binder, e.g. cement · CPC title

• B09B2101/90

  Soil, e.g. excavated soil from construction sites · CPC title

• B09B3/70 Primary

  Chemical treatment, e.g. pH adjustment or oxidation (involving an extraction step B09B3/80) · CPC title