Heating – Work chamber having heating means – Having means by which work is progressed or moved mechanically
Reexamination Certificate
2001-12-20
2003-10-07
Lu, Jiping (Department: 3749)
Heating
Work chamber having heating means
Having means by which work is progressed or moved mechanically
C432S128000, C432S133000, C432S143000, C432S147000, C432S149000
Reexamination Certificate
active
06629838
ABSTRACT:
THIS INVENTION relates to a process and installation for the treatment of solid material by means of an endothermic chemical reaction. More particularly, the invention relates to a process for the treatment of a solid material such as a mineral to cause it to undergo an endothermic chemical reaction, and to an installation for the treatment of such solid material undergoing said endothermic reaction, the process and installation being suitable for, but not limited to, the treatment of a mineral at elevated temperatures at which the mineral being treated become sticky and/or soft. The invention also relates to a kiln forming part of the installation.
The Applicant is aware of the abstract of Japanese Published Patent Application 56166155, published under publication number JP-A-58067813, which abstract has been published in Patent Abstracts of Japan, Volume 7, No. 155 (C-175), Jul. 7, 1983. This abstract discloses a process for the treatment by reduction and sintering of a solid material by passing the solid material along the inside of a tunnel kiln comprising a horizontally extending tunnel having a hollow interior. The solid material is supported on a series of supports as it passes along the kiln, the supports being moved successively along the interior of the kiln. The solid material is heated, by means of radiant heat radiated on the solid material, as it passes along the kiln, to a temperature at which it undergoes an endothermic reaction. A fuel such as coke oven gas is supplied to a burner in the roof of the kiln, so that heat is produced by combustion in a combustion zone in the upper part of the kiln, separate from a reaction zone where reduction and sintering of the solid material is carried out, in the lower part of the kiln. The Applicant is also aware of U.S. Pat. No. 4,978,294 which discloses a process whereby, in a rotary furnace, partitions are used to keep combustion gases separate from minerals being reduced, so that re-oxidation of the minerals is resisted. The Applicant is further aware of published International Patent Application WO-A-93/16342 which discloses shapes in the form of extruded pipes consolidated from particles of solid material, which are stacked on supports during heating thereof.
According to one aspect of the invention there is provided a process for the treatment of a solid material, the process including the process steps of:
passing the solid material along the inside of a kiln comprising a horizontally extending tunnel having a hollow interior;
supporting the solid material on a succession of supports as it passes along the kiln, the supports being moved successively along the interior of the kiln; and
heating the solid material, by means of radiant heat radiated on to the solid material, as it passes along the kiln, to a temperature at which the solid material undergoes an endothermic chemical reaction,
the heat which is radiated on to the solid material being produced by combustion in a combustion zone separated by at least one member of the group consisting of partitions, panels and baffles from a reaction zone through which the solid material supported on the supports passes during the heating.
According to another aspect of the invention there is provided a process for the treatment of solid material, the process including the steps of:
passing the solid material along the inside of a kiln comprising a horizontally extending tunnel having a hollow interior;
supporting the solid material on a succession of supports as it passes along the kiln, the supports being moved successively along the interior of the kiln; and
heating the solid material, by means of radiant heat radiated on to the solid material, as it passes along the kiln, to a temperature at which the solid material undergoes an endothermic chemical reaction,
the process including the step of consolidating particles of the solid material into shapes which are arranged in stacks on the supports.
Each support may be in the form of a wheeled trolley, the process including loading a succession of the trolleys with the solid material to be treated, each trolley being loaded on an upwardly facing support surface of a load bed of the trolley, the moving of the supports along the interior of the kiln being by rolling the loaded trolleys in succession along a path extending, below the interior of the kiln, along the length of the kiln,
The kiln may have an inlet end and an outlet end, each of which ends is provided with an airlock, the process including the steps of inserting the loaded trolleys in succession into the inlet end of the kiln, and withdrawing the loaded trolleys in succession from the outlet end of the kiln, the airlocks acting to promote the maintenance of an atmosphere inside the kiln which is different from the ambient atmosphere outside the kiln, which atmosphere inside the kiln promotes the endothermic reaction.
Heating the mineral may be by radiant heat provided in a reaction zone in the tunnel by heating surfaces of electric heating elements in the tunnel. However, heating the mineral is preferably by radiant heat emitted by one or more heating surfaces facing towards the mineral on the trolleys in said reaction zone in the interior of the tunnel, the heating surfaces being heated by a combustion gas and being provided by one or more partitions in the interior of the tunnel and the combustion taking place on the side of each partition remote from the mineral on the trolleys. In other words, the heating of the solid material may be by radiant heat emitted by one or more heating surfaces in the interior of the kiln and facing towards the solid material passing along the kiln, each heating surface being provided by a partition in the interior of the kiln and each partition having opposite sides facing respectively towards and away from the solid material, each partition being heated by a combustion gas located on the side of the partition facing away from the solid material. Instead, heating may be by radiation from a flame created by combustion of a gas.
The process may include the step of consolidating particles of the solid material into shapes to promote heating thereof in the kiln, eg by both convective and radiant heating, the shapes being stacked on the supports and the process including the step of removing from the vicinity of the shapes any gaseous products formed by the heating of the shapes, eg formed by the endothermic reaction and which can inhibit continuance of such reaction. The process may, accordingly, include the step of stacking consolidated shapes on the trolleys. Instead or in addition, the solid material or mineral to be heated may be loaded on trays, the trays in turn being loaded in spaced positions on the trolleys, each trolley carrying a plurality of trays. When consolidated shapes are employed, they may be in the form of extrusions or compacted mouldings, the solid material being milled prior to its being extruded or moulded and optionally being mixed with one or more constituents selected from reagents such as reductants which participate in the endothermic reaction, selected from catalysts or fluxes which can enhance the endothermic reaction, and selected from binders for facilitating the consolidation.
The solid material may, in the interior of the tunnel and prior to the radiant heating thereof to cause the endothermic reaction, be subjected to pre-heating. The pre-heating may be by radiant heating, eg similar to the heating in the reaction zone, or preferably by convective heating, for example by forced convection achieved by circulating a hot gas transversely through the interior of the tunnel and over the solid material on the trolleys. The hot gas may be heated by a heat exchanger, or it may be a hot combustion gas. In the interior of the tunnel and after the endothermic reaction, the reaction product formed by the endothermic reaction may be cooled by conveying the reaction product along a cooling zone in the interior of the tunnel, prior to withdrawal of the trolleys from the tunnel. In the case of reducing reactions, gas p
Morrison Alexander McClaren
Stone Andrew Kenneth
Van Vuuren David Steyn
Lu Jiping
Rothwell Figg Ernst & Manbeck
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