REFRACTORY BRICKS

Abstract

A process for preparing a refractory brick, comprises: mixing a refractory aggregate and a binder composition to obtain a refractory mixture wherein the binder composition comprises:

(a) carbohydrate reactant(s) comprising reducing sugar(s) or carbohydrate reactant(s) that yield reducing sugar(s) in situ under thermal conditions and nitrogen-containing reactant(s) and/or

(b) curable reaction product(s) of reducing sugar(s) and nitrogen-containing reactant(s) pressing the refractory mixture to obtain a moulded refractory brick; and firing the moulded refractory brick.

Claims

1. A process for preparing a refractory brick, comprising mixing a refractory aggregate and a binder composition to obtain a refractory mixture wherein the binder composition comprises: (a) carbohydrate reactant(s) comprising reducing sugar(s) or carbohydrate reactant(s) that yield reducing sugar(s) in situ during firing and nitrogen-containing reactant(s) and/or (b) reaction product(s), notably curable reaction products, of reducing sugar(s) and nitrogen-containing reactant(s) pressing the refractory mixture to obtain a moulded refractory brick; and firing the moulded refractory brick.

2. A process in accordance with claim 1 wherein the binder composition is a solid binder composition.

3. A process in accordance with claim 1 wherein the binder composition is an aqueous binder composition having a solid content in the range of 40 wt % to 85 wt % determined as bake out solids by weight after drying at 140 C. for 2 hours.

4. A process in accordance with claim 1 wherein the binder composition is substantially formaldehyde free.

5. A process in accordance with claim 1 wherein the process is substantially free of ammonia emission.

6. A process in accordance with claim 1 wherein the process is substantially free of sulphur emission.

7. A process in accordance with claim 1 wherein moulded refractory brick, prior to firing, comprises between 0.5 wt % and 5 wt % of the binder composition measured by loss on ignition.

8. A process in accordance with claim 1 wherein the binder composition comprises (i) between 50% to 99% by dry weight, preferably between 75% to 95 by dry weight of carbohydrate reactant(s) comprising reducing sugar(s) and/or carbohydrate reactant(s) that yield reducing sugar(s) in situ during firing; and (ii) between 1% to 50% by dry weight, preferably between 5% to 25% by dry weight, of nitrogen-containing reactant(s).

9. A process in accordance with claim 1 wherein the binder composition when mixed with the refractory aggregate comprises at least 50% by dry weight of reaction products of nitrogen containing reactant(s) and reducing sugar reactant(s).

10. A process in accordance with claim 1 wherein the nitrogen-containing reactant(s) are selected from the group consisting of a primary amine, a di-primary diamine, HMDA and combinations thereof.

11. A process in accordance with claim 1 wherein the carbohydrate reactant(s) are selected from the group consisting of dextrose, fructose, xylose, and mixtures thereof.

12. A process in accordance with claim 1 wherein the refractory aggregate comprises magnesite, dolomite, alumina, oxides, bauxite, quartz, carbonates, ores, clay, silica, chromite, and combination thereof.

13. A refractory brick obtained by the process of claim 1.

Description

[0042] The invention will be explained in more details in the non-limiting examples below.

[0043] An aqueous binder composition was prepared by adding HMDA (192.86 g; 70 w % in H.sub.2O) to 1163.37 g of dextrose monohydrate (DMH 90.9 w % dextrose and 9.1 w % water of crystallisation) and 1057.50 g of fructose (FRU; 100% solid) and 586.28 g of water. This binder composition corresponds to 47:47:6 w % DMH:FRU:HMDA at a 75 wt.-% in H.sub.2O.

EXAMPLE 1:

[0044] 1000 kg of binder impregnated refractory aggregate material was prepared by blending i) a magnesia aggregate (MgO, 100%, grain size 0.3-0.4 mm) ii) 20 kg of the above aqueous binder composition iii) 4 kg of water and iv) magnesia powder (MgO, 100%, grain size <0.3 mm). The mixture was mixed and then pressed (251.3*252.5*90-114 mm, l*w*t wedged, length*width*thickness) with a pressure up to 150 N/mm.sup.2 and a cycle time of 25 s/per stone. Between 35 and 40 stones were obtained.

EXAMPLE 2:

[0045] 1000 kg of binder impregnated refractory aggregate material was prepared by blending i) a magnesia aggregate (60% MgO, 40% Chrome-ore, grain size 0.3-0.4 mm) ii) 20 kg of the above aqueous binder composition iii) 2 kg of water and iv) magnesia/Chrome-ore powder (60% MgO, 40% Chrome-ore, grain size <0.3 mm). The mixture was mixed and then pressed (251.3*252.5*90-114 mm, l*w*t wedged, length*width*thickness) with a pressure up to 150 N/mm.sup.2 and a cycle time of 25 s/per stone. Between 35 and 40 stones were obtained.

[0046] The mixing of the batches went without any issues and were comparable to lignosulfonate binder. The pressing occurred without any problems and the green strength was good.