CN107253847A - The method that a kind of utilization ocean waste silt prepares environmentally friendly arenolite - Google Patents

Abstract

The invention provides a method for preparing environmentally friendly artificial sandstone from marine waste silt, which includes the following steps: (1) filtering to remove impurities (2) dehydrating to reduce the water content (3) mixing the silt with curing agents, additives, activators, etc. Stir evenly and solidify to obtain solidified sludge (4) Use a suitable method to shape the solidified sludge and make it into a pebble shape (5) Curing for 7 to 10 days. The environment-friendly artificial sandstone material prepared by using the discarded marine silt in the invention has the remarkable characteristics of stable performance, low cost, environment-friendliness and the like. It not only effectively solves the problem of waste sludge polluting the environment, but also greatly reduces the consumption of natural gravel and pebbles, and avoids environmental and energy problems caused by the mining of natural sand and gravel. It can be widely used in various port projects and road projects. construction, reduce engineering costs, and have high promotion and application value.

Description

A method of using marine waste sludge to prepare environmentally friendly artificial sand

technical field

The invention belongs to the technical field of civil engineering and building materials, and in particular relates to a method for preparing environmentally friendly artificial sand and gravel by utilizing marine waste silt.

Background technique

The construction and maintenance of port projects in coastal areas will produce a large amount of waste sludge with high moisture content. Traditional land reclamation, ocean dumping and other treatment methods have a series of problems such as large area occupation, long time consumption, high cost and serious pollution. Therefore, under the concept of sustainable development, how to deal with waste sludge in a reasonable, environmentally friendly and effective way has important practical significance for building a resource-saving and environment-friendly society.

The construction of port projects also requires a large amount of sand and gravel materials, but the sand and gravel resources are very scarce, especially the traditional sand and gravel mining not only causes a large consumption of non-renewable natural sand and gravel resources, but also seriously damages the ecological environment, and the process of sand and gravel crushing and decomposition It will consume a lot of energy, and there are problems such as high pollution, high energy consumption and high CO ₂ emissions.

Contents of the invention

The purpose of the present invention is to overcome the shortcomings of the above-mentioned technologies, and provide a method for preparing environmentally friendly artificial sandstone from marine waste sludge. The prepared artificial sandstone has good performance and is a good substitute for natural sandstone. Using marine waste silt as raw material, and local materials according to local conditions, the cost is low, which effectively reduces the cost of port engineering construction, and at the same time realizes the resource utilization of marine waste silt.

The technical scheme that the present invention improves is as follows:

A method for preparing environmentally friendly artificial sand by using marine waste silt, the method includes the following steps,

(1) Filtration, filtering to remove large particles of stones, aquatic plants and other debris in the sludge;

(2) Dehydration, centrifugal dehydration of the filtered sludge to a moisture content of 45%~75%;

(3) Solidification. Mix and stir the dehydrated sludge with curing agent, additives and alkaline activator according to the following ratio evenly to form solidified sludge. The mass parts of each component are composed of 40~65 parts of sludge, 15~ of curing agent 35 parts, 10~20 parts of additives, 1~15 parts of basic activator;

The curing agent is composed of 15-35 parts of early-strength ordinary Portland cement and 0-15 parts of quicklime;

The additive mass composition is 3~10 parts of fly ash, 1~5 parts of slag, 1~5 parts of cement slag, 1~3 parts of steel slag, and 1~2 parts of desulfurized gypsum;

The mass of the alkaline activator is divided into 0-5 parts of water glass (Na ₂ SiO ₃ 9H ₂ O), 0-5 parts of sodium hydroxide, and 0-5 parts of sodium carbonate, and the sum of the three parts by mass is 1-15 parts ;

(4) Forming, forming the solidified sludge through a forming machine, and then making pebble-like sand and gravel materials of uniform size through suitable manual or mechanical methods;

(5) Curing, the obtained pebble-like sand and gravel are naturally cured for 7 to 10 days.

The effect of each component among the present invention:

silt. Marine discarded silt is the raw material for making environmentally friendly sand and gravel in the present invention, and provides a certain water environment.

Hardener. 1. The hydration reaction between cement and the water content in the silt produces gelling substances such as hydrated calcium silicate and hydrated calcium aluminate, so that the silty soil particles are cemented together; 2. On the one hand, quicklime has strong water absorption. It can significantly reduce the water content of the sludge in the initial stage of the reaction; 3. CaO, the main component in the quicklime, reacts with the water content in the sludge to generate a large amount of Ca(OH) ₂ , which is the active SiO ₂ and Al ₂ O ₃ contained in the cement and additives. , Fe ₂ O ₃ , etc. to provide a suitable alkaline environment for hydration reactions.

additive. The mixed fly ash, slag, cement slag, steel slag, desulfurized gypsum and other substances are all solid wastes with pozzolanic effects. On the one hand, waste utilization effectively treats these wastes. On the other hand, the active SiO contained in these substances _2. Al ₂ O ₃ , Fe ₂ O ₃ , etc. can also produce gelatinous substances such as calcium silicate hydrate and calcium aluminate hydrate under alkaline conditions, which can bond silty soil particles.

stimulant. Promote the disintegration of SiO ₂ , Al ₂ O ₃ , Fe ₂ O ₃ structures in additives, accelerate the reaction of additives and curing agents to form gelling substances, and at the same time effectively stimulate the activity of mineral components in soil particles and accelerate the hydration process.

Beneficial effects of the present invention:

The invention provides a method for preparing environmentally friendly artificial sand and gravel by using marine waste silt, which can process waste marine silt to produce sand and gravel materials with suitable particle sizes, which has the advantages of stable performance, low cost, and environmental friendliness. It can be widely used in various port projects, road projects and other engineering constructions to partially or completely replace natural gravel and pebbles and reduce project costs. On the one hand, it reasonably and effectively solves a series of problems such as the accumulation of waste silt and the pollution of the environment. On the other hand, the treated silt can be used as an environmentally friendly artificial sandstone material for engineering construction, which can greatly reduce the impact on natural gravel. , The consumption of pebbles, thereby effectively avoiding the environmental and energy problems caused by the mining process of natural sand and gravel, and realizing the purpose of harmless and resourceful treatment of sludge waste, has good economic and social value.

Description of drawings

Fig. 1 is the flowchart of preparation method of the present invention.

detailed description

Several embodiments of the present invention are described below, and the content of the present invention is not limited thereto at all. Fig. 1 shows the flow chart of the preparation method of the present invention.

Example 1

(1) Filtration, take the discarded dredged marine silt from a certain port, and filter to remove large particles of stones, aquatic plants and other debris in the silt;

(2) Dehydration, centrifuging and dehydrating the filtered sludge to a moisture content of 65%;

(3) Solidification. Take 45 parts of dehydrated sludge, 30 parts of curing agent, 18 parts of additives, and 7 parts of alkaline activator, and put them into a mixer to mix and stir evenly to form a solidified sludge. The composition of some components by mass is as follows :

Curing agent, 20 parts of 52.5R grade early strength ordinary Portland cement, 10 parts of quicklime;

Additives, 10 parts of fly ash, 4 parts of slag, 2 parts of cement slag, 1 part of steel slag, 1 part of desulfurized gypsum;

Alkaline activator, 5 parts of water glass, 1 part of sodium hydroxide, 1 part of sodium carbonate;

(4) Forming, the solidified sludge is formed into a cylindrical shape in a piston extrusion molding machine, and pebble-like sand and gravel materials of uniform size are formed by suitable manual or mechanical methods;

(5) Curing, the obtained pebble-like sand and gravel can be naturally cured for 8 days.

The environmental-friendly artificial sand produced in Example 1 has a compressive strength of 21MPa and a crushing value of 14.3% after being dried at 105°C, and its performance index should conform to JGJ52-2006 "Quality and Inspection Methods of Sand and Stone for Ordinary Concrete". The relevant provisions of the Standard, and it is superior to the sandstone material performance (compressive strength of 16MPa, crushing value of 17%) made of single cement as the curing agent under the same conditions.

Example 2

(1) Filtration, take the discarded dredged marine silt from a certain port, and filter to remove large particles of stones, aquatic plants and other debris in the silt;

(2) Dehydration, centrifuging and dehydrating the filtered sludge to a moisture content of 52%;

(3) Solidification. Take 52 parts of dehydrated sludge, 25 parts of curing agent, 15 parts of additives, and 8 parts of alkaline activator, and put them into a mixer to mix and stir evenly to form a solidified sludge. The composition of some components by mass is as follows :

Curing agent, 52.5R grade early-strength ordinary Portland cement 15 parts, quicklime 10 parts;

Additives, 9 parts of fly ash, 3 parts of slag, 1 part of cement slag, 1 part of steel slag, 1 part of desulfurized gypsum;

Alkaline activator, 5 parts of water glass, 2 parts of sodium hydroxide, 1 part of sodium carbonate;

(4) Forming, the solidified sludge is formed into balls in an extrusion molding machine to form pebble-like sand and gravel materials of uniform size;

(5) Curing, the obtained pebble-like sand and gravel can be naturally cured for 9 days.

The environmental-friendly artificial sandstone obtained in Example 2 is dried at 105°C and measured to have a compressive strength of 18MPa and a crushing value of 15%. The relevant provisions of the Standard, and it is superior to the sandstone material performance (compressive strength of 14MPa, crushing value of 18%) made of single cement as the curing agent under the same conditions.

Example 3

(1) Filtration, take the discarded dredged marine silt from a certain port, and filter to remove large particles of stones, aquatic plants and other debris in the silt;

(2) Dehydration, centrifugal dehydration of the filtered sludge to a moisture content of 58%;

(3) Solidification. Take 58 parts of dehydrated sludge, 30 parts of curing agent, 10.4 parts of additives, and 1.6 parts of alkaline activator, and put them into a mixer to mix and stir evenly to form a solidified sludge. The mass composition of some components is as follows :

Curing agent, 52.5R grade early-strength ordinary Portland cement 15 parts, quicklime 15 parts;

Additives, 5 parts of fly ash, 1 part of slag, 1 part of cement slag, 2 parts of steel slag, 1.4 parts of desulfurized gypsum;

Alkaline activator, 1.6 parts of water glass;

(4) Forming, the solidified sludge is formed into a cylindrical shape in a piston extrusion molding machine, and pebble-like sand and gravel materials of uniform size are formed by suitable manual or mechanical methods;

(5) Curing, the obtained pebble-like sand and gravel can be naturally cured for 7 days.

The environmental-friendly artificial sandstone obtained in Example 3 is dried at 105°C, and the compressive strength value is 27.3MPa, and the crushing value is 13.9%. It is better than the performance of sand and gravel materials made of single cement as curing agent under the same conditions (compressive strength is 20MPa, crushing value is 17%).

Example 4

(1) Filtration, take the discarded dredged marine silt from a certain port, and filter to remove large particles of stones, aquatic plants and other debris in the silt;

(2) Dehydration, centrifuging and dehydrating the filtered sludge to a moisture content of 45%;

(3) Solidification. Take 40 parts of dehydrated sludge, 15 parts of curing agent, 10 parts of additives, and 1 part of alkaline activator, and put them into a mixer to mix and stir evenly to form a solidified sludge. The composition of some components by mass is as follows :

Curing agent, 14 parts of 52.5R grade early strength ordinary Portland cement, 1 part of quicklime;

Additives, 3 parts of fly ash, 2 parts of slag, 2 parts of cement slag, 1 part of steel slag, 2 parts of desulfurized gypsum;

Alkaline activator, 1 part of sodium hydroxide;

(4) Forming, the solidified sludge is formed into a cylindrical shape in a piston extrusion molding machine, and pebble-like sand and gravel materials of uniform size are formed by suitable manual or mechanical methods;

(5) Curing, the obtained pebble-like sand and gravel can be naturally cured for 7 days.

The environmental-friendly artificial sandstone obtained in Example 4 is dried at 105 DEG C, and the compressive strength value is 15.6MPa, and the crushing value is 16%. It is better than the performance of sand and gravel materials made of single cement as curing agent under the same conditions (compressive strength is 10MPa, crushing value is 21%).

Example 5

(1) Filtration, take the discarded dredged marine silt from a certain port, and filter to remove large particles of stones, aquatic plants and other debris in the silt;

(2) Dehydration, centrifugal dehydration of the filtered sludge to a moisture content of 75%;

(3) Solidification. Take 65 parts of dehydrated sludge, 35 parts of curing agent, 20 parts of additives, and 15 parts of alkaline activator, and put them into a mixer to mix and stir evenly to form a solidified sludge. The mass composition of some components is as follows :

Curing agent, 23 parts of 52.5R grade early strength ordinary Portland cement, 12 parts of quicklime;

Additives, 5 parts of fly ash, 5 parts of slag, 5 parts of cement slag, 3 parts of steel slag, 2 parts of desulfurized gypsum;

Alkaline activator, 5 parts of water glass, 5 parts of sodium hydroxide, 5 parts of sodium carbonate;

(4) Forming, the solidified sludge is formed into a cylindrical shape in a piston extrusion molding machine, and pebble-like sand and gravel materials of uniform size are formed by suitable manual or mechanical methods;

(5) Curing, the obtained pebble-like sand and gravel can be naturally cured for 10 days.

The environmental-friendly artificial sandstone obtained in Example 5 is dried at 105°C, and the compressive strength value is 32MPa, and the crushing value is 12%. According to the relevant provisions of the Method Standard, it is better than the sandstone material performance (compressive strength of 25MPa, crushing value of 14.3%) made of single cement as the curing agent under the same conditions.

Claims (5)

1. A method for preparing environmentally friendly artificial sand by utilizing marine waste silt, is characterized in that, comprising the following steps: (1) Filtration, filtering to remove large particles of stones, aquatic plants and other debris in the sludge; (2) dehydration, centrifuging and dehydrating the filtered sludge to a water content of 45% to 75%; (3) solidify, the mud after dehydration is mixed with solidifying agent, additive, alkaline activator in the following ratio and stirred evenly to form solidified mud, and the parts by mass of each component are (4) molding, the solidified silt is molded by a molding machine, and then artificially or mechanically made into pebble-like sand and gravel materials of uniform size; (5) Curing, the obtained pebble-like sand and gravel are naturally cured for 7-10 days. 2. The method according to claim 1, wherein the sludge is discarded and dredged marine sludge from a port. 3. The method for preparing environmentally friendly artificial sandstone from marine waste silt according to claim 1, characterized in that the curing agent consists of 15-35 parts of early-strength ordinary Portland cement, 0-15 parts of quicklime share. 4. The method for preparing environment-friendly artificial sand and gravel by using marine waste silt according to claim 1, characterized in that, the additives consist of 3 to 10 parts by mass of fly ash, 1 to 5 parts of slag, and 1 to 5 parts of cement slag. 5 parts, steel slag 1-3 parts, desulfurization gypsum 1-2 parts. 5. The method for preparing environment-friendly artificial sand and gravel by using marine waste sludge according to claim 1, characterized in that, the composition of the alkaline activator in parts by mass: water glass (Na ₂ SiO ₃ 9H ₂ O) 0-5 parts, 0 to 5 parts of sodium hydroxide, and 0 to 5 parts of sodium carbonate, the sum of the three parts by mass is 1 to 15 parts.