CN107282877B - A method of regeneration recycles sodium silicate sand - Google Patents

Abstract

The invention relates to a method for regenerating and reusing water glass molding sand. In molding sand casting, when the pouring casting is condensed and cooled to 500±50°C, the water glass sand mold is sequentially impacted by high-pressure water flow, so that the sand mold is completely eroded and collapsed into loose sand, and obtained For the primary treatment sand containing residual silicic acid gel, the primary treatment sand is soaked in a low-concentration HF acid aqueous solution, stirred and filtered to obtain the secondary treatment sand, and the secondary treatment sand is washed, dried, and sieved to obtain the regenerated sand. The new sand accounts for 60%-80% and the reclaimed sand accounts for 20-40% by weight and mixes, adding a disintegrating agent to make a new water glass sand mold. The invention has the advantages of high regeneration efficiency, low cost, no pollution, cleanness and environmental protection, and is a novel green water glass molding sand regeneration method.

Description

A method for regenerating and reusing water glass molding sand

technical field

The invention relates to a method for regenerating and utilizing water glass molding sand by a wet method, which is especially suitable for various _CO2 gas-hardened water glass molding sands with excellent collapsibility.

Background technique

Water glass sand casting has been widely used in recent years due to its high molding efficiency, low cost, and easy operation. my country is a big country in the production of castings, and the output of castings ranks second in the world, among which sand casting accounts for the vast majority (80% to 90%) of the foundry industry. Sand casting requires a large amount of sand for production. According to statistics, every 1 ton of qualified castings produced in my country can produce about 1.2 tons of waste sand. A large amount of foundry waste sand is discharged every year, occupying a lot of waste sand sites and affecting the environment.

Due to the defects of poor mold sand collapsibility and difficult recycling of old sand existing in sand casting, its further development is limited. The regeneration problem has been correspondingly improved, but there will be problems such as the decrease of the strength of the molding sand and the high cost of the regeneration technology of the old sand, which cannot be promoted on a large scale. Patent CN 103056291 A discloses a recycling method for used water glass sand, vibrating and crushing the old water glass sand to remove impurities, the crushed sand has a particle size of 20-40 mesh; washing with high temperature water, heating the water to above 90°C, Then pour the broken water glass old sand particles, stir and scrub to remove the adhesive film on the surface of the sand particles; dry the water glass particles after washing at a high temperature of 300-350°C, and perform dry regeneration to remove Sodium oxide, dust and residual sinter in old sand. This method also has high cost and low utilization rate.

Contents of the invention

The purpose of the present invention is to overcome above-mentioned deficiency and provide a kind of method of recycling water glass molding sand, this method cost is low, pollution-free, recycling rate height, effect is good.

The technical scheme that the present invention takes is:

A method for regenerating and reusing water glass molding sand, comprising steps as follows:

(1) In sand casting, when the pouring casting is condensed and cooled to 500±50°C, the high-pressure water flow is used to impact the water glass sand mold in sequence, so that the sand mold is completely eroded and collapsed into loose sand. During this process, the sand particles and the water flow collide with each other and are quickly cooled , part of the silicic acid gel mold adhered to the surface of the sand grains swells and cracks and falls off, and the disintegrating agent in the sand mold is completely dissolved in water and separated from the sand grains, thereby obtaining primary treatment sand containing residual silicic acid gel;

(2) Soak the primary treatment sand with a low-concentration HF acid aqueous solution, stir and filter, corrode the residual silicic acid gel adhering to the surface of the sand grains, and obtain the secondary treatment sand, rinse the secondary treatment sand with clean water and heat Dry and sieve through 40 meshes to obtain regenerated sand;

(3) Mix according to the weight ratio that new sand accounts for 60%-80% and regenerated sand accounts for 20-40%, add disintegrating agent and make new water glass sand mold.

The preferred CO2 gas _- hardened water glass sand mold of the described water glass sand mold of step (1) in the above-mentioned method; Described collapsing agent is _CO The commonly used collapsing agent of gas hardened water glass sand mold, preferred hydrophilic or water-soluble collapsing agent.

The high-pressure water flow sequentially erodes the sand mold at a pressure of 0.1-0.4 MPa and a speed of 4-10 mm/s.

The part of the silicic acid gel that can swell, crack and fall off accounts for 40±5wt%, and the remaining part accounts for 60±5wt%.

The mass concentration range of the low-concentration HF acid aqueous solution described in step (2) is 1-10%, and the soaking and stirring time is 5-20 minutes.

The disintegrating agent described in step (3) is preferably a hydrophilic or water-soluble disintegrating agent.

The method of the invention adopts wet regeneration, the water used can be recycled, no dust pollution will be generated, no sewage will be discharged, the high-pressure water flow can completely disperse the sand mold, and remove the disintegrating agent and about 40% of the silicic acid coagulation produced in the curing process. Glue; the regeneration efficiency of old sand is high, which can reach more than 90%. The performance index of the mixed sand made after recycling is not much different from that of new sand, and has excellent collapsibility, which can meet the requirements of sand casting; the invention has low cost and no pollution , clean and environmentally friendly, is a new green water glass sand recycling method.

Detailed ways

Further description will be given below in conjunction with specific examples.

The molding sand regenerated in the embodiment of the present invention is _CO2 air-hardened water glass molding sand added with a disintegrating agent, which has excellent collapsibility, and the same type and amount of disintegrating agent is also added when making new CO2 air _- hardened water glass sand molds with regenerated sand . The disintegrating agent is selected from conventional hydrophilic or water-soluble disintegrating agents, such as kaolin, starch, saccharin and the like.

Example 1

A method for regenerating and reusing water glass molding sand, comprising steps as follows:

(1) Make a sand mold with CO ₂ gas hard water glass sand added with a collapsing agent. After pouring the casting into the sand mold, when the pouring casting condenses and cools down to 500°C, use high-pressure water flow at a pressure of 0.1-0.4MPa and 4-10mm/s The sand mold is eroded in sequence at a high speed, so that the sand mold is completely eroded and collapsed into loose sand. In this process, the sand grains at 500°C and the high-pressure water flow collide and rub against each other, and are cooled rapidly, and the silicic acid gel mold that adheres to the surface of the sand grains accounts for about 40%. Swelling, cracking and falling off, the disintegrating agent in the sand mold is completely dissolved in water, separated from the quartz sand, and the primary treated sand containing the remaining 60% silicic acid gel is obtained;

(2) soak and stir the primary treatment sand with 5wt% concentration of HF acid aqueous solution for 10 minutes and then filter to corrode the residual silicic acid gel adhered to the surface of the sand particles to obtain the secondary treatment sand, and rinse the secondary treatment sand with clear water After rinsing, heat and dry, and sieve through 40 mesh to obtain regenerated sand;

(3) account for 70% according to new sand and reclaimed sand account for 30% weight ratio and mix, add collapsing agent and make new CO ₂ air-hardened water glass sand mold.

Example 2

A method for regenerating and recycling water glass molding sand, the steps are the same as in Example 1, the difference is that step (3) is mixed according to the weight ratio of new sand accounting for 80% and regenerated sand accounting for 20%, adding a disintegrating agent to make new CO _gas hard water Glass sand mold.

Example 3

A method for regeneration and recycling of water glass molding sand, the steps are the same as in Example 1, the difference is that step (3) is mixed according to the weight ratio of new sand accounting for 60% and regenerated sand accounting for 40%, and adding a disintegrating agent to make new _CO gas hard water Glass sand mold.

Table 1 is the performance comparison data of the new sand, regenerated sand and the mixed sand of the examples. It can be seen that the performance index of the recovered mixed sand is not much different from that of the new sand, and has excellent collapsibility.

Table 1

The above is a detailed introduction of the present invention in conjunction with specific embodiments, and the protection scope of the present invention is not limited thereto.

Claims (6)

1. a kind of method that regeneration recycles sodium silicate sand, characterized in that including steps are as follows：

(1) in molding sand casting when pouring cast part condensation is cooled to 500 ± 50 DEG C water-glass sand is impacted with high pressure water flow sequence Type keeps the complete erosion of sand mold defeated and dispersed at loose sand, and the high pressure water flow is with the speed of the pressure of 0.1-0.4MPa and 4-10mm/s Sequence erosion sand mold, this process sand grains is mutually hit with flow to be rubbed and is quickly cooled down, and the part of sand grain surface is adhered to Silicic acid gel mould swelling cracking falls off, and dispersant is fully immersed into water in sand mold, is detached with sand grains, to obtain containing remnants The single treatment sand of silicic acid gel；The silicic acid gel can be swollen the part that cracking falls off and account for 40 ± 5wt%；

(2) the HF aqueous acids of single treatment sand low concentration are impregnated, agitation and filtration, makes the silicon for being adhered to sand grain surface remnants Acid gel obtains after-treatment sand after eroding, heating, drying after after-treatment sand is rinsed with clear water is regenerated after sieving Sand；

(3) it accounts for 60%-80% according to fresh sand and reclaimed sand accounts for the weight ratio mixing of 20-40%, addition dispersant is fabricated to newly Waterglass sand mold.

2. the method that a kind of regeneration according to claim 1 recycles sodium silicate sand, characterized in that step (1) institute The waterglass sand mold stated selects CO₂Air hardening waterglass sand mold.

3. the method that a kind of regeneration according to claim 1 recycles sodium silicate sand, characterized in that step (1) institute The dispersant stated is dispersant that is hydrophilic or being dissolved in water.

4. the method that a kind of regeneration according to claim 1 recycles sodium silicate sand, characterized in that step (2) institute The mass concentration range 1-10% of the HF aqueous acids for the low concentration stated, time 5-20 minute of soaking and stirring.

5. the method that a kind of regeneration according to claim 1 recycles sodium silicate sand, characterized in that step (2) institute That states is sieved through 40 mesh excessively.

6. the method that a kind of regeneration according to claim 1 recycles sodium silicate sand, characterized in that step (3) institute The dispersant stated selects dispersant that is hydrophilic or being dissolved in water.