阅读说明：本技术 一种无水泥浇注料用镁质结合剂及其制备方法 (Magnesium binder for cement-free castable and preparation method thereof ) 是由 肖国庆 陈建军 丁冬海 任耘 于 2019-10-08 设计创作，主要内容包括：本发明公开了一种无水泥浇注料用镁质结合剂及其制备方法,包括将含有结晶水的镁质原料经高温烘烤脱去结晶水,然后研磨过筛得到镁质结合剂。所述的镁质原料可为柠檬酸镁、草酸镁和葡萄酸镁等其中任一种,所述的高温为100～400℃,烘烤时间为1h～200h。镁质结合剂在加水搅拌时会形成网状结构而具有凝结性能,镁质结合剂制备的耐火浇注料具有优异常温力学性能,在高温原位生成的尖晶石可提高浇注料的抗侵蚀性能和抗热震性能；该结合剂具有不污染环境,生产工艺简单,生产能耗低等优点,且适用范围广,适用于高铝质,刚玉质,碳化硅质等无水泥浇注料。(The invention discloses a magnesia bonding agent for a cement-free castable and a preparation method thereof. The magnesium raw material can be any one of magnesium citrate, magnesium oxalate, magnesium gluconate and the like, the high temperature is 100-400 ℃, and the baking time is 1-200 h. The magnesia binder can form a net structure when being stirred by adding water and has condensation performance, the refractory castable prepared by the magnesia binder has excellent normal-temperature mechanical property, and the spinel generated in situ at high temperature can improve the erosion resistance and thermal shock resistance of the castable; the binder has the advantages of no environmental pollution, simple production process, low production energy consumption and the like, has wide application range, and is suitable for cement-free castable materials such as high-alumina, corundum, silicon carbide and the like.)

1. The preparation method of the magnesia binder for the cement-free castable refractory is characterized by comprising the steps of roasting a magnesia raw material containing crystal water at high temperature to remove the crystal water, grinding the magnesia raw material and sieving the crystal water with a 325-mesh sieve to obtain the magnesia binder, wherein the magnesia binder is used for preparing the cement-free castable refractory.

2. The method for preparing the magnesia binder for a cement-free castable according to claim 1, wherein the magnesia raw material is any one of magnesium citrate, magnesium oxalate and magnesium gluconate, the high temperature is 100 to 400 ℃, and the baking time is 1 to 200 hours.

3. The method of claim 1, wherein the purity of the magnesium raw material is greater than 90%.

4. The method of producing a magnesium binder for cement-free castable according to claim 1, wherein the magnesium binder forms a network structure when stirred with water and has a setting property.

5. The method of claim 1, wherein the magnesium binder is added to the castable in an amount of 1 to 15% by weight of the castable refractory.

6. The magnesium binder for cement-free castable, which is prepared by the method for preparing the magnesium binder for cement-free castable according to any one of claims 1 to 5, wherein the magnesium binder is used in a castable in the following way:

and mixing and stirring the weighed magnesia binder and the refractory castable raw material according to the addition amount of the magnesia binder in the refractory castable and the mixture ratio of the castable raw material, then adding a proper amount of water, stirring, and forming a castable sample by vibration.

Technical Field

The invention belongs to the technical field of unshaped refractory materials, and particularly relates to a magnesium bonding agent for a cement-free castable and a preparation method thereof.

Background

Refractory castable is a typical unshaped refractory material. The binding agent is an important component of the refractory castable, and the construction performance, the drying performance and the service performance of the refractory castable are greatly dependent on a binding system of the binder and the refractory castable. Calcium Aluminate Cement (CAC) becomes the most widely used bonding agent at present because of the advantages of good rheological characteristics, green strength and the like, but CaO in the cement can cause the refractory material to generate low-melting-point phases such as anorthite, gehlenite, tricalcium aluminate and the like at high temperature, so that the high-temperature service performance (refractoriness, thermal shock resistance, erosion resistance and high-temperature rupture strength) of the refractory castable is reduced; and the cement bonded castable needs extra attention to the curing and dewatering process to avoid the phenomenon of peeling and even cracking in the primary heating process.

For this purpose, researchers have developed low-cement, ultra-low-cement and cement-free bonded castables, wherein the cement-free binders mainly comprise Hydrated Alumina (HA), phosphates, silica sol and the like. The cement-free binder does not generate a low-melting-point phase at high temperature, so that the refractoriness and high-temperature performance of the castable are improved. However, the hydrated alumina HAs a high specific surface area, so that the castable needs a high water adding amount and a long stirring time, and the HA combined castable HAs low permeability after being hardened, so that the castable is easy to crack in a dehydration process. The silica sol combined castable has difficult demoulding caused by low demoulding strength, and SiO is introduced into a system by adding the silica sol into the castable₂Thereby affecting the high-temperature use performance of the material. And the phosphate binder decomposes the volatilized harmful gas (P) in the using process₂O₅) It can corrode the equipment and pollute the environment.

The prior amide binder (CN 102417319A) for the cement-free castable provides an amide binder suitable for high-alumina, corundum and silicon nitride cement-free castable, but the amide binder can release harmful gas (NH) in the use process₃). The patent technology of a bonding agent (CN 102515805A) for a magnesia refractory castable proposes a bonding agent for the magnesia refractory castable; the binding agent consists of magnesium chloride hexahydrate and a coagulant, the coagulant consists of light-burned magnesia powder and active magnesia powder, but the magnesia in the binding agent is hydrated to generate larger volume expansion so as to cause cracks on a casting material green body, and the document MgOFumes as a porous binder for in situ particulate refractory castings stated that light-burned magnesium oxide micropowder, which has high specific surface area and activity, is used as a binder to make the casting material have higher green strength, but the addition of a magnesium oxide hydration inhibitor must be strictly controlled by the binder, otherwise, cracking of the casting material green can also occur.

Disclosure of Invention

In order to overcome the defects and shortcomings of the technology, the invention provides a magnesium bonding agent for a cement-free castable and a preparation method thereof.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a magnesia binder for a cement-free castable and a preparation method thereof comprise the steps of roasting a magnesia raw material containing crystal water at a high temperature to remove the crystal water, grinding the magnesia raw material and sieving the crystal water with a 325-mesh sieve to obtain the magnesia binder, wherein the magnesia binder is used for preparing the cement-free refractory castable, the normal-temperature mechanical property of the cement-free castable can be obviously improved, and the corrosion resistance and the thermal shock resistance of the castable can be improved by spinel generated in situ at a high temperature.

Further, the magnesium raw material can be any one of magnesium citrate, magnesium oxalate, magnesium gluconate and the like, the high temperature is 100-400 ℃, and the baking time is 1-200 h.

Furthermore, the purity of the magnesium raw material is more than 90 percent.

Furthermore, the magnesium bonding agent can form a net structure when being stirred by adding water, thereby having coagulation property.

Furthermore, the addition amount of the magnesium bonding agent in the castable is 1-15% of the weight of the refractory castable.

Further, the use method of the magnesium binder in the castable is as follows:

and mixing and stirring the weighed magnesia binder and the refractory castable raw material according to the addition amount of the magnesia binder in the refractory castable and the mixture ratio of the castable raw material, then adding a proper amount of water, stirring, and forming a castable sample by vibration.

Compared with the prior art, the invention has the following technical effects:

(1) the spinel generated by the magnesia binder in situ at high temperature can improve the erosion resistance and thermal shock resistance of the castable. The micropores produced by pyrolysis can relieve the stress produced by the in-situ spinel generation.

(2) The magnesium binder does not generate a low-melting-point phase at high temperature, and improves the refractoriness and high-temperature performance of the castable.

(3) The magnesium bonding agent prepared by the invention improves the early strength of the cement-free castable; no harmful gas is released during the use process.

(4) The magnesium binder is added into the refractory castable in a powder mode, so that the problem that the sol binder is difficult to store and transport is effectively solved.

(5) The magnesium binder has wide application range, is suitable for non-cement castable materials such as high alumina, corundum, silicon carbide and the like, and is also suitable for unshaped refractory materials in the forms of refractory ramming mass, gunning material, plastic material and the like.

Drawings

Figure 1 is a microstructure of a magnesium citrate binder of the present invention and its hydration products;

FIG. 2 shows the cross-sectional profile of a sample after erosion of aluminate cement bond casting material (CAC) and magnesium citrate bond casting Material (MC).

Detailed Description

The following detailed description of embodiments of the invention refers to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The magnesium binding agent for the cement-free castable and the preparation method thereof are complied with the technical scheme, and the magnesium binding agent comprises a magnesium raw material containing crystal water, wherein the crystal water is removed through high-temperature baking, then the magnesium raw material is ground and sieved by a 325-mesh sieve to obtain the magnesium binding agent, the magnesium raw material can be any one of magnesium citrate, magnesium oxalate, magnesium gluconate and the like, the high temperature is 100-400 ℃, and the baking time is 1-200 hours. The magnesium bonding agent is used for preparing the cement-free refractory castable, and the magnesium bonding agent can form a net structure and has condensation performance when being stirred by adding water.