GB2196331A - Resin-bonded taphole mix - Google Patents

Abstract

A slow-setting resin-bonded taphole mix comprises a substantially uniform admixture of a refractory grog and a phenolic resin (e.g. a novolak resin), a solvent for the resin (e.g. triethylene glycol), and a clay.

Description

SPECIFICATION Resin-bonded taphole mix BACKGROUND OF THE INVENTION The present invention relates to taphole mixes for use in metal-making furnaces and particularly large production blast furnaces.

At the present time, a variety of refractory materials are utilized to seal tapholes in such furnaces, but have not been found to be satisfactory, particularly for high temperature extrusion.

Most satisfactory to date have been those refractory grogs wherein the grog is bonded by a combination of clay and either pitch or creosote. While pitch and creosote bonded grogs for use as taphole mixes are operable, they are not entirely satisfactory in that the give off toxic fumes and accordingly are hazardous to use. Moreover, the pitch and/or creosote bonded refractory grogs are more difficult to remove from the taphole; as by drilling after use.

Attempts to overcome this problem by using resin-bonded refractory grogs have not proven successful, for a variety of reasons. Amongst other reasons, they are more costly than the pitch and creosote, set too rapidly, and have insufficient hot strength after the taphole mix is put into place, thus effectively precluding their use in large production blast furnaces in which high temperatures are attained.

SUMMARY OF THE INVENTION The resin-bonded taphole mix of the present invention overcomes the problems of the prior art to provide a low cost, effective, non toxic, high temperature extrudable mix suitable for use in metal-making furnaces, including high.temperature blast furnaces.

Briefly, the present invention comprises a slow setting resin-bonded taphole mix consisting essentially of a substantially uniform admixture of a refractory grog and a bonding composition consisting essentially of a clay, a low volatile high softening point phenolic resin, and a high boiling point solvent. The invention also comprises the method of closing a taphole comprising applying to said taphole the foregoing mix and curing said mix.

DETAILED DESCRIPTION The two essential components of the present invention are the refractory grog and the bonding composition. As to the refractory grog, it can be any alumina grog, silica grog, calcined fire clay grog, pyroholite grog, fused alumina grog, fused mullite grog, sintered alumina grog, or mixture thereof presently used in taphoie mixes. Conventionally, these grogs also contain materials to give increased slag resistance such as silicon carbide, graphite, or other carbon forms or mixtures thereof.

In the present invention, it is preferred to use a grog consisting essentially of alumina-silica calcines, fused alumina with silicon carbide and graphite.

The proportions by weight of the various components in the grog in the present invention are not critical so long as the components are present in amounts sufficient to give the strength and other properties required for the particular conditions of the metal-making furnace in which the taphole mix is to be utilized. For high temperature use; such as blast furnaces, it is also in some cases advisable to add silicon in an amount sufficient to increase the mix's hot strength after cure; although this does add to cost. The amount of silicon added will vary dependent upon the particular grog used, but is suitably about 1.5 to 3 parts by weight for each 100 parts by weight of the refractory grog and clay in the mix.

With respect to the bonding composition, clay has been utilized in the past together with the creosote or pitch for bonding purposes and it is again utilized for this same purpose. The novelty of the present invention is to utilize a low volatile high softening point phenolic resin and a high boiling point solvent for said resin which is compatible therewith. As previously noted, resins have not been satisfactory before since resin bonds and systems set up so much faster that pitch-creosote systems that it precluded their use from large production blast furnaces where high temperatures are utilized.

As to the clay used in the bonding composition, it can be any conventionally used for that purpose, such as ball clays, bentonites, and the like and mixtures thereof.

The two critical elements in the bonding composition are the phenolic resin and the high boiling point solvent therefor. It is preferred to use a solid rein; most suitably a powdered one, although pre-dissolved resins can also be used. The powdered phenolic resin must have, as noted, low volatiles and high softening point. Suitable for this purpose are the novolac resins with softening points above 105"C, such as Rid 2477 from BORDEN INC.

With respect to the solvent, it must not only be compatible with the resin, but have a boiling point above 285"C, particularly when being utilized in high temperature blast furnaces. Most suitable for this purpose is triethylene glycol; although other solvents such as tetraethylene glycol, or mixtures thereof can be utilized.

As to proportions, while large amounts of resin, such as 12% by weight based on 100 percent by weight of the mix (refractory grog, clay, and silicon (if any)) can be utilized, from a cost viewpoint, as well as effectiveness, it has been found that amounts as low as 4% can be utilized, although it is preferred to utilize from about 6% to 8% by weight. Correspondingly, larger amounts of the solvent would be required with the larger amounts of resin, but solvent also can be utilized in an amount preferably from 8% to 11% by weight, although amounts from about 7% to 15% can be utilized.

The invention will be further illustrated in connection with the following examples which are set forth for purposes of illustration only. In these examples, the workability index, green bulk density, cold and hot crush strength, drip slag test and extrusion pressure testing are determined utilizing the conventional apparatus and procedures for that purpose in testing taphole mixes.

Also, the proportions of materials in the mix is in percent by weight, with the plus additions; resin and solvent, being based on 100% by weight of the mix.

EXAMPLES 1-4 A series of mixes was prepared by admixing in the conventional manner various refractory grogs and utilizing a typical pitch bonding in one mix and a phenolic resin and solvent therfor as the bonding agent for the other mixes. The various components of the mixes and the results of the tests thereon are shown in Table I below.

TABLE I EXAMPLES Mix Designation: 1 2 3 4 Mix: Calcined Fire Clay Grain (Mo. Flint Grain) 3/10 mesh ------ 18% ------ 10/28 ------ 16 28/65 ------ 6 Ball Mill Fines (BMF) 32 32 29.5 27 Crude Kyanite (-100 mesh) ------ 10 P-Carb ~~~~ 3 Amorphous Graphite (MEXALOY) ------ 5 Ball Clay (GLEASON) 10 10 12.5 15 Plus Additions: Powdered Pitch 10.5 - - Methyl Napthaline 10.5 - - Powdered Phenolic Resin (BORDEN RD 2477) - 8 8 8 Triethylene Glycol - 9.5 9.5 10 Mix Temperature, C: 47 40 42 47 Workability Index: 47 25 24 28 Extrusion Pressure at 1500C,kPa To initiate flow: 345 207 345 276 To maintain flow: 621 276 414 345 Cold Crushing Strength, kPa After drying at 260 C (Av 3: 6330 8530 12110 10600 Weight Loss, % After Heating at 260 C (Av 3): 6.9 4.5 4.8 5.4 Reheat Change after 30 min at 1095 C, Reducing Linear Change, Ht, %: +1.5 +0.1 +2.4 +1.7 Linear Change, Dia., %: +3.6 +5.5 +4.8 +4.3 Weight Loss, %: 14.2 14.5 14.3 14.5 Hot Crushing Strength at 1095 C, kPa: (load rate was 182 tgimin 5240 5171 5654 4551 Drip Slag Test at15950C using 5009 of Duquesne pF Slag (Reducing) Volume loss, cm 50 59 - EXAMPLES 5-11 The procedures of Examples 1 to 4 were followed but using different grogs and different proportions of resin and solvent. The results are set forth in Table II below.

TABLE II EXAMPLES Mix Designation: 5 6 7 8 9 10 11 Mix: Calcined Alumina-silica (Ucal 60) 3/10 mesh ----------- 12% 10/28 mesh ----------- 11 28/65 mesh ----------- 5 BMF 25 27 30 32 29.5 32 27 Silicon Carbide (DCF) 15 15 10 10 10 10 Crude Kyanite (-lOOm) ----------- 10 Amorphous Graphite (MEXALOY) 7.5 7.5 7.5 7.5 10 7.5 7.5 Silicon (-100m) 2 - 2 - - - - Ball Clay (GLEASON) ---------- 12.5 -------- Plus Additions: Phenolic Resin (BORDEN RD 2477) 8 8 8 8 8 6 6 Triethylene Glycol 10.25 10.25 10.25 10.01 10.0 10.25 10.25 Mixing Time, minb 8 8 7 6 6 10 8 Mix Temperature, C : 43 46 48 47 50 44 46 Workability Index t6,35Kt weight): 25 27 29 31 25 22 21 Green Bulk Density, t:g/m3 2291 2291 2291 2307 2275 2323 2323 (Av 3): Cold Crushing Strength,kpa After Curing 6 hours at 260 C (Av 3): 15168 125485 133758 122727 119279 96527 97216 Hot Crushing Strength,kPa At 1095 C: 8274 5516 6895 3930 5447 6757 - Drip Slag Testing at 1538 0C Using 1000 gms Duquesne BF slag, Reducing 3 Volume Eroded, cm3 : 11 - - - - 21 Extrusion Pressure, kPa 150 C, 2 hour hold Initial: 345 - - - - 827 Hold: 2620 - - - - 3585 Raw Stock Cost,US/tonne: 354 327 329 303 307 280 305 In all instances with the resin-bonded products of the present invention there was lower fuming, none of the toxicity that is present with pitch and creosote, as well as the ability to have high temperature extrusion. Also the mix of the present invention extrudes easier and more quickly at all temperature levels thus resulting in lower strain in the mud gun used to apply the mix to the taphole.

Moreover, the resin-bonded mixes were softer and acted to plug up any cracks in the taphole.

Moreover, the resin was easier to clean out and drill out than with the pitch or creosote bonded resins.

Claims (12)

1. A slow-setting resin-bonded taphole mix which comprises a substantially uniform mixture of a refractory grog, a phenolic resin, a solvent for the resin, and a clay.

2. The taphole mix of claim 1, which comprises 4 to 12% of the resin and 7 to 15% of the solvent, the percentages being by weight with respect to the total weight of the refractory grog and the clay.

3. The taphole mix of claim 2, which comprises 6 to 8% of the resin and 8 to 11% of the solvent.

4. The taphole mix of any preceding claim, wherein the solvent has a boiling point of at least 285"C.

5. The taphole mix of claim 4, wherein the solvent is triethylene glycol and/or tetraethylene glycol.

6. The taphole mix of any preceding claim, which additionally includes silicon in an amount sufficient to increase the hot strength after cure.

7. The taphole mix of any preceding claim, wherein the refractory grog comprises aluminasilica calcines, fused alumina, silicon carbide or graphite.

8. The taphole mix of any preceding claim, wherein the resin has a softening point above 105"C.

9. The taphole mix of claim 8, wherein the resin is a Novolac resin.

10. The taphole mix of claim 9, wherein the solvent is triethylene glycol and the clay is ball clay.

11. The taphole mix of claim 1, substantially as exemplified herein.

12. A method of sealing a taphole in a metalmaking furnace, which comprises applying the mix of any preceding claim to the taphole and curing the mix to seal the taphole.