A BLAST PIPE, PREFERABLY FOR USE IN METALLURGICAL PROCESSES

Abstract: A high-temperature resistant blast pipe is primarily intended for delivering gas, such as oxygen, and, when appropriate, solid material to metallurgical processes, and incorporates a layer of refractory material comprising a refractory mixture of solid particles and an alkali-silicate based binder. The blast pipe is characterized in particular in that the major constituent of the binder is of the type polymerized alkali silicate.

Description: A blast pipe, preferably for use in metallurgical pro¬ cesses. The present invention relates to a blast pipe which is intended for transporting gas, such as oxygen and/or solid material primarily in conjunction with metallurgical pro¬ cesses, and which can withstand high temperatures, said pipe comprising for this purpose at least one layer of re¬ fractory material which includes a refractory mixture of particulate solids and an alkali-silicate binder. Blast pipes of the kind intended here are used to blow gas, such as oxygen, argon or nitrogen, or gaseous mix¬ tures into primarily molten metal baths in conjunction with metallurgical processes, such as in the manufacture of steel in electrosteel furnaces. Applications are also found in which such pipes are used to inject a mixture of gas and solids intended for metallurgical purposes. Blast pipes of essentially the aforesaid kind and intended for the aforesaid purpose are known to the art. One prob¬ lem encountered with known blast tubes, however, is that peeling occurs due to the mechanical weakness of the layer. Furthermore, the refractory mix from which the layers are formed often requires very exclusive and expensive con¬ stituents. Known blast pipes are made of steel and the outwardly facing parts of the pipe are alloyed with alumi¬ nium by diffusion , in order to improve the high temperature properties.This loy constitutes a very expensive partof the pipe manufacturing process. The object of this invention is therefore to provide a blast pipe which can be produced at relatively low costs and which will also have a long useful life when used in the aforesaid context, thus satisfying the high demands placed on such blast pipes in this latter regard. The invention thus relates to a blast pipe which is in¬ tended primarily for delivering gas, such as oxygen, and when applicable, solids to metallurgical processes, and which will resist high temperatures and which, to this end, incorporates a layer of refractory material which includes a refractory mixture of particulate solids and an alkali- silicate based binder. The inventive blast pipe is particularly characterized in that the primary constituent of the binder is a polymerized alkali silicate. The invention will now be described in more detail with reference to embodiments thereof. The inventive blast pipe comprises a pipe onto which the aforesaid layer is applied. The pipe is normally made of steel, although other materials may also be used. For example, there may be used a steel pipe which has a tubular paper casing fitted externally thereon, this paper casing preferably being impregnated with a refractory substance, such as alkali silicate. The pipe may also be made pre¬ dominantly of paper. Pipes which are made essentially of plastic materials, fibre glass or like materials are also conceivable. According to one preferred embodiment the binder used in the refractory material of said layer is of the kind used in the manufacture of glues and adhesives. A particularly preferred binder is one which is sold by EKA Nobel AB under the designation BINDZIL FK 10, or some other binder which is used in the manufacture of glues or adhesives and which has a similar composition. Preferably the particulate solids of the refractory mix of solid particles incorporating said refractory material comprise essentially metal oxides. In many cases it is preferred that the refractory mixture of solid particles has a composition which is similar to the composition of furnace lining material and corresponds to the kind used in metallurgical vessels intended for metallurgical processes of the kind intended here. According to one embodiment the aforesaid mixture comprises essentially a so-called magnesite mixture, the predominant constituent of which is magnesium oxide (MgO) and the re¬ maining Constituents of which include further oxides, such as lime (CaO), quartz (Si0 2 ), iron oxide (Fe 2 0 3 ) and alumi¬ nium oxide (Al 2 0 3 ), preferably in the quantities of ca 60-93 % MgO, ca 2-10 % CaO, ca 1-9 % Si0 2 , ca 1-5 % Fe 2 0 3 and ca 1-9 % Al-O-.. In many cases it is preferred to incorporate a given per¬ centage of talc in the aforesaid layer, in addition to the refractor mixture of solid particles and binder. According to one specific embodiment of the invention, the layer is produced from a mixture of ca 8-12, preferably ca 10, litres of water; ca 3-5,preferably ca , kilograms of binder in the form of BINDZIL FK10 or the like; ca 30-50, preferably ca 40, kilograms of magnesite mixture; ca 0.5-2, preferably ca 1, kilogram of talc; and when applicable ca 0.05-0.25, preferably ca 0.1 kilograms of powdered carbon. The layer is applied to the pipe, by dipping the pipe into a liquid mixture of, e.g. the kind described in the pre¬ ceding paragraph, whereafter the layer of mixture thus ap¬ plied is dried. The pipe is preferably kept open at both ends during the dipping process, so that a layer is applied to both the external and internal surfaces of the pipe. The function of the inventive blast pipe will be understood in all essentials from the aforegoing. A layer produced in accordance with the invention is very tough and also re¬ sistant to high temperatures. The talc addition facili- tates application of the layer forming mixture to the pipe surfaces. It will be understood from the aforegoing that the inven¬ tive blast pipe affords considerable advantages compared with blast pipes produced in accordance with known tech¬ niques. The invention has been described in the aforegoing with reference to a number of preferred embodiments. It will be understood, however, that other embodiments are conceivable and that minor modifications can be made to the described embodiments without departing from the concept of the in¬ vention. For example, refractory mixtures may be used which comprise other solid particles than those described, for example other mixtures in which the constituents are still pre¬ dominantly metal oxides. It is also conceivable for the external and internal layer to be of mutually different kinds. Thus, according to one embodiment the solid parti¬ cles of the refractory mix intended for an external layer may consist of a magnesite mixture of the aforesaid kind, whereas the solid particles of the refractory mix intended for an internal layer may comprise essentially bauxite.

Claims: CLAIMS 1. A blast pipe which is intended for delivering gas, such as oxygen and, when applicable, solid material to metallurgical processes and which is capable of withstand¬ ing high temperatures, said pipe comprising for this pur¬ pose at least one layer of refractory material comprising a refractory mixture of solid particles and an alkali- silicate based binder, characterized in that the major constituent of the binder fs of the type polymerized alcalϊ silicate. 2. A blast pipe according to claim 1, characterized in that the binder comprises a binder of the kind used in the manufacture of glues or adhesive, and is a binder of the kind sold by EKA Nobel AB under the designation BINDZIL FK 10, or some other binder used in the manufacture of glues and having a similar composition. 3. A blast pipe according to claim 1 or 2, characterized in that the solid particles substantially are metal oxides. 4. A blast pipe according to claim 3, characterized in that the refractory mixture of solid particles has a com¬ position similar to the composition of the foundary lining material or the like used in metallurgical vessels. 5. A blast pipe according to claim 1, 2, 3 or 4, charac¬ terized in that the mixture comprises essentially a so- called magnesite mixture, the major constituent of which is MgO and the remaing constituents of which are further oxides, such as CaO, Si0 2 , Fe 2 0 3 and Al 2 0.-,. 6. A blast pipe according to claim 5 , characterized in that said mixture comprises essentially ca 60-93 % MgO ca 2-10 % CaO ca 1-9 % Si0 2 ca 1-5 % Fe 2 0 3 ca 1-9 % 1 2 0 3 7. A blast pipe according to claim 1, 2, 3, 4, 5 or 6, characterized in that the layer incorporates a given per¬ centage of talc in addition to said refractory mixture of solid particles and binder. 8. A blast pipe according to claim 1, 2, 3, 4, 5, 6 or 7, characterized in that said layer is produced from a mixture of ca 8-12, preferably ca 10, litres of water; ca 3-5, preferably ca 4, kilogram of binder in the form of BINDZIL Fk 10 or the like; ca 30-50, preferably ca 40, kilogram of magnesite mixture; ca 0.5-2, preferably ca 1, kilogram of talc and, when applicable, ca 0.05-0.2, preferably ca 0.1 kilogram of powdered carbon. 9. A blast pipe according to claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that said layer is applied externally to a steel pipe. 10. A blast pipe according to claim 1, 2, 3, 4, 5, 6, 7 or 8, characterized in that said layer is applied external¬ ly to a tubular paper casing fitted to a steel pipe and preferably impregnated with a refractory substance. 11. A blast pipe according to any of the preceding claims, characterized in that the layer is applied both to the external and to the internal surface of the pipe. 12. A blast pipe according to any of the preceding claims, characterized in that the pipe has an internal layer in which the solid particles of the refractory mixture consist essentially of bauxite.

Inventors: LARSSON ARNE, LARSSON, ARNE
Applicants: OXY TUBEN AB, OXY-TUBEN AB
Application year: 1987
Main classification: F27D3
IPC codes: B22D1, C04B12, C04B28, C04B35, C21C5, F16L9, F27D1, F27D3