COLD-SETTING DRY VIBRATABLE MIX

Abstract

The invention relates to a refractory dry vibratable mix which sets at room temperature when water is added, for use in metallurgical vessels and comprising a refractory main component, a binder and a retarder.

Description

FIELD OF THE INVENTION

The invention relates to a dry vibratable mix in accordance with the preamble of claim 1.

TECHNICAL BACKGROUND

The invention concerns an unshaped refractory dry vibratable mix which in particular sets at room temperature. Preferably, this is used as a dry vibratable mix for lining metallurgical vessels, for example of a tundish or the like, and can be described as a cold-setting tundish dry vibratable mass.

In the case of unshaped refractory masses, these are usually a mixture which consists of a refractory main component (for example MgO, SiO₂, sintered dolomite, olivine) and one or more binders.

Setting of refractory masses of this type may be carried out using organic or indeed inorganic binders, or in fact combinations of the two.

Thus, for example, dried dry vibratable mixes are known which contain powdered phenol resin as a binder. Hardening of these dry vibratable mixes takes place at approximately 200-250° C. Furthermore, cold-setting dry vibratable mixes are employed. In this case, a 2-component binder system is used in the liquid form, such as water glass/ester or resin/ester combinations.

However, these systems suffer from several disadvantages. Thus, for example, the tacky water glass could result in abrasion of specific machine parts. Binder systems containing resin result in odor and emissions, for example because of the release of ammonia. Other disadvantages of these binders are linked to their limited storage capability.

However, binders are known which are added to a dry vibratable mix in powdered form and are then activated by the addition of water as a reactant or as a solvent. Under certain circumstances, dry vibratable mixes which are currently known which are based on acid/base binder systems can result in the release of sulphur-containing compounds. Furthermore, when using calcium supports as bases, the CaO uptake in many grades of steel may be considered to be undesirable.

DESCRIPTION OF THE INVENTION

From the foregoing, the objective of the invention is to provide an improved dry vibratable mix in accordance with the preamble of the independent claims.

This objective is achieved by means of the features of the independent claims.

The dry vibratable mix in accordance with the invention advantageously contains the binder components in the powdered form and can set at room temperature when water is added as a solvent or reactant, but does not suffer from the disadvantages described above.

In one embodiment, a binder consisting of magnesium oxide and an alkali phosphate (for example potassium dihydrogen phosphate or an alkali polyphosphate) or ammonium dihydrogen phosphate or mixtures of these phosphates is provided. Preferably, the phosphate which is used is a potassium dihydrogen phosphate. Magnesium oxide and potassium dihydrogen phosphate react by taking in water to form crystalline potassium magnesium phosphate hexahydrate (set product). The water which is added acts both as a solvent and as a reactant in which it is taken up as water of crystallization. Upon heating, annealing-resistant magnesium pyrophosphate is formed at approximately 250° C. Beyond approximately 1000° C., this is converted into magnesium phosphate.

Furthermore, the refractory mass in accordance with the invention is characterized in that it contains at least one retardant in the form of a carboxylic acid. The carboxylic acid used is, for example, citric acid, tartaric acid, malic acid, maleic acid, etc.

Further features and embodiments of the invention are defined in the claims.

Claims

1. A refractory dry vibratable mix for use in metallurgical vessels, which sets at room temperature when water is added, characterized by a refractory main component, a binder and a retardant.

2. The dry vibratable mix as claimed in claim 1, characterized in that the main component includes one or more of sintered magnesia, fused magnesia, olivine, quartz, sintered dolomite, and secondary raw materials based on MgO.

3. The dry vibratable mix as claimed in claim 1, characterized in that said binder is based on magnesium oxide, an alkali phosphate and/or ammonium dihydrogen phosphate.

4. The dry vibratable mix as claimed in claim 3, characterized in that said binder include alkali phosphate, said alkali phosphate includes potassium dihydrogen phosphate and/or alkali polyphosphate.

5. The dry vibratable mix as claimed in claim 1, characterized by said retardant includes carboxylic acid.

6. The dry vibratable mix in particular as claimed in claim 1, comprising (by weight %): 5-95% of MgO or olivine, and/oramorphous SiO2, <1%, and/orcarboxylic acid, >1%<5%, and/oralkali phosphate, >1 %<5%.

7. The dry vibratable mix in particular as claimed in claim 1, comprising a refractory component such as magnesia and no additional MgO.

8. The dry vibratable mix in particular as claimed in claim 1, comprising a refractory component such as magnesia and in particular additional MgO, <2% by weight, <1% by weight, <0.1% by weight MgO.

9. The dry vibratable mix as defined in claim 5, wherein said carboxylic acid includes one or more of citric acid, tartaric acid, malic acid, maleic acid or malonic acid.

10. A refractory dry vibratable mix which sets at room temperature when water is added, characterized by a refractory main component, a binder and a retardant said refractory main component includes one or more materials selected from the group consisting of sintered magnesia, silica, fused magnesia, olivine, quartz, sintered dolomite, and secondary raw materials based on MgO; said binder includes one or more materials selected from the group consisting of magnesium oxide, an alkali phosphate, magnesium pyrophosphate, magnesium phosphate, and ammonium dihydrogen phosphate; said retardant includes one or more materials selected from the group consisting of citric acid, tartaric acid, malic acid, maleic acid, and malonic acid.

11. The refractory dry vibratable mix as defined in claim 10, wherein said binder includes magnesium oxide and one or more of said alkali phosphate and ammonium dihydrogen phosphate.

12. The refractory dry vibratable mix as defined in claim 10, wherein said refractory main component includes magnesia.

13. The refractory dry vibratable mix as defined in claim 11, wherein said refractory main component includes magnesia.

14. The refractory dry vibratable mix as defined in claim 10, comprising: 5-95 wt. % refractory main component>1 wt. %-<5 wt. % binder>1 wt. %-<5 wt. % retardant.

15. The refractory dry vibratable mix as defined in claim 13, comprising: 5-95 wt. % refractory main component>1 wt. %-<5 wt. % binder>1 wt. %-<5 wt. % retardant.

16. The refractory dry vibratable mix as defined in claim 10, wherein said refractory main component includes silica, a content if said silica is less than 1 wt. %.

17. The refractory dry vibratable mix as defined in claim 15, wherein said refractory main component includes silica, a content if said silica is less than 1 wt. %.

18. The refractory dry vibratable mix as defined in claim 10, wherein said binder includes carboxylic acid; said retardant includes alkali phosphate.

19. The refractory dry vibratable mix as defined in claim 17, wherein said binder includes carboxylic acid; said retardant includes alkali phosphate.

20. A refractory dry vibratable mix which sets at room temperature when water is added; said refractory dry vibratable mix including a refractory main component, a binder and a retardant;said refractory main component constitutes 5-95 wt. % of said refractory dry vibratable mix; said refractory main component essentially consisting of sintered magnesia, fused magnesia and/or olivine; said binder constitutes >1-<5 wt. % of said refractory dry vibratable mix, said binder includes one or more materials selected from the group consisting of potassium dihydrogen phosphate, an alkali polyphosphate and ammonium dihydrogen phosphate; said retardant constitutes >1-<5 wt. % of said refractory dry vibratable mix, said retardant includes one or more materials selected from the group consisting of citric acid, tartaric acid, make acid, maleic acid, and malonic acid; said refractory dry vibratable mix includes less than 1 wt. % SiO2, said refractory dry vibratable mix includes less than 2 wt. % MgO from a source other than said refractory main component.

21. The refractory dry vibratable mix as defined in claim 20, wherein said refractory main component essentially consists of olivine, said refractory main component including less than 1 wt. % MgO from a source other than said refractory main component.