Abstract:
Procédé de fusion de scrap en alliage d'aluminium contenant du lithium dans lequel (i) on approvisionne du scrap contenant des alliages de type aluminium-lithium (étape d'approvisionnement) ; (ii) on prépare un lit initial de métal liquide d'une première composition (étape de préparation du lit initial de métal liquide) dans un four de fusion ; (iii) on charge ledit scrap sur ledit lit initial de métal liquide de façon à créer à la surface dudit lit de métal liquide un matelas flottant d'épaisseur contrôlée dudit scrap (étape de chargement), ledit matelas fondant partiellement au contact dudit lit de métal liquide de façon à obtenir un bain de métal liquide d'une seconde composition pouvant être égale ou différente de la première composition , la teneur en lithium dudit bain de métal liquide d'une seconde composition étant comprise entre 0,1% et préférentiellement 0,2% à 2,5% en poids ; (iv) on prélève le métal liquide (étape de prélèvement) dudit bain de métal liquide d'une seconde composition. Le procédé selon l'invention présente des avantages techniques et économiques : - il ne nécessite pas d'investir dans une installation particulière, notamment à atmosphère inerte, - il ne nécessite pas, ou il minimise l'utilisation de consommables onéreux tels que du gaz inerte, car la formation d'un matelas de scrap d'épaisseur contrôlée permet de protéger de l'oxydation la surface du métal liquide d'une façon étonnement efficace.
Abstract:
A method of melting metal scrap in a molten melting media, the method comprising (a) providing a source of molten melting media in a furnace (2), the melting media in the furnace (2) having a first surface level; (b) providing a first melting bay (6, 40) in fluid communication with the furnace (2) to receive molten melting media from the furnace to provide a body of molten melting media in the first melting bay for purposes of melting floatable metal scrap, the first melting bay having: (i) a bottom (28); and (ii) an outer wall (42) connected to the bottom defining the first melting bay, the outer wall having a generally spiral shaped cross section terminating in a mouth (60) of a channel (58) for removing melting media and molten scrap (30) to an adjacent bay (12, 56), the spiral shaped cross section receding away from a generally central axis of the first melting bay.
Abstract:
The noxious fumes leaving the dry hearth chamber (112) of a metal recovery furnace (102) are fed to an incinerator (106) where they are burnt at high temperature with oxygen. The hot, clean exhaust gas is introduced to the bath chamber (111) of the furnace (102). This arrangement typically saves 60 % of fuel costs. Furthermore, since the fumes are recycled the exhaust emission to atmosphere simply reflects the input of fuel and oxygen. This can be nearly one eighteenth of a conventional plant thereby reducing filter and/or scrubber duty and stack size. This arrangement thus has particular advantages in fuel conservation and conservation of the environment. It enables metals to be recycled in an installation which produces little pollution and which utilizes the heat available in the waste material to conserve fuel.
Abstract:
A device for liquid pumping comprises a pump chamber (21) arranged to receive a subportion of the liquid to be pumped. The pump chamber is provided with means for cyclic variation of the pressure in the pump chamber between an overpressure and a depression with regard to the pressure in the chamber (17) where the main portion of the liquid is. The pump chamber (21) is further provided with an input opening (22) and an output opening (23). The input opening (22) has a substantially lower flow resistance in the direction into the pump chamber (21) than in the opposite direction, and the output opening (23) has a substantially lower flow resistance in the direction out of the pump chamber than in the opposite direction, so that with a depression in the pump chamber a larger liquid quantity is sucked into the pump chamber through the input opening (22) than through the output opening (23) and that with an overpressure in the pump chamber a larger liquid quantity is forced out through the ouput opening (23) than through the input opening (22). Due to this fact a net liquid quantity can be sucked in through the input opening and forced out through the output opening. The device makes it possible to pump many types of liquids, for example molten metal, without the use of movable valves.
Abstract:
The scrap that is to be charged into an electric arc furnace (11) is preheated by a gas in a closed circuit (21, 20, 23, 22, 17) and this gas is heated in a heat exchanger (17) by the exhaust fumes from the furnace. A minor part of the circulating gas is continuously led off to a burner (25) in which it is burnt with a gas as fuel at such a high temperature that rest products such as dioxines are destroyed. The exhaust fumes from the burner (25) is supplied to the exhaust fumes of the furnace (11) upstream of the heat exchanger (17). In another burner (27), another minor part of the circulating gas is continuously burnt with a gas fuel at a substantially lower temperature so that hydrocarbons in the circulating gas burn. The exhaust fumes from the burner (27) are returned to the closed circuit.
Abstract:
Method and plant for pre-heating, transforming and melting a metal charge comprising metal scrap, in an electric arc furnace (12) associated with a tunnel (11) to transport, pre-heat and discharge the scrap. The furnace (12) comprises a hearth (13) and a roof (14) through which the electrodes (15) pass. The method provides that the furnace (12) is weighed at least periodically in order to detect the quantity of discharged scrap present inside the furnace (12) itself, that the temperature of the liquid bath inside the furnace (12) is detected at least periodically and that at least the discharge delivery of the scrap inside the furnace (12) is detected by weighing and is regulated in order to maintain the temperature of the liquid bath around a pre-determined value.
Abstract:
The present invention provides a process plant for the production of molten steel from primary and/or secondary ferrous materials in which no free oxygen is permitted to contact directly carbon-containing iron melts, comprising: - i) at least three pairs of furnaces (1,2; 3,4;5,6), each furnace of a pair having a hearth base (36) and being interconnected so as to form a continuous flowpath loop for molten metal, the first pair (1,2) defining an iron making loop (A) and the second and third pair (3,4;5,6) defining primary and secondary steel refining loops (B,C) respectively, (ii) means (8) for transferring molten metal from the ironmaking loop (A) to the first refining loop (B) and from the first refining loop (B) to the second refining loop (C), (iii) means for controllably supplying heat to, and removing heat from metal in the furnaces (1,2,3,4,5,6), whereby, in use a central region of metal (19a) in the furnace (1,2,3,4,5,6) becomes or is maintained in its molten state and a peripheral region of the metal (20) is maintained in a solid state such that the molten metal (19a) is contained within a stable solid shell of metal (20), said solid metal shell (20) defining the walls of the furnace (1,2,3,4,5,6), (iv) for each furnace (1,2,3,4,5,6), a removable lid (23), an enclosed space (25) being defined between the hearth (36), the lid (23) and the solid metal shell (20) defining the walls of the furnace (1,2,3,4,5,6), (v) a lifting arrangement (34,35) for controllably raising out of and lowering into the melt any plant items, so that upon shut down, said items can be removed prior to solidification of the molten metal (19a).
Abstract:
A metal scrap melting submergence device for a chargewell of a melting furnace comprises an open top chamber (116) including walls of a heat resistant material, an inlet (126) positioned in a side wall of the chamber, an outlet (124) positioned in the base of said chamber, and a sloped ramp (121) adjacent said side wall of the chamber. The ramp rises from a base (120) spirally along the chamber circumference and includes an inner wall (122) from an inner edge of the ramp. The top edge of said inner wall will be at approximately the same height as the terminal edge of the ramp.
Abstract:
The facility is designed to win metals, for instance zinc, from metal wastes and can be successfully used in industry. The facility represents an inclined casing faced inside with a heat insulating material and provided with mounted interchangeable reflectors made of bead-formed metal sheets. Onto a cantilever-supported casing shaft is set up a removable drum with a cross-shaped stiffening member inside. Solid wastes can be charged into the drum directly on the areas of formation and disposal of waste, still they can also be charged without removing the drum from upon the casing shaft through the open cover. Soot is taken away from the drum through the open cover, too. The facility has a temperature sensor and an automatic operating conditions control unit; while rotating, the drum is heated by means of a burner. Availability of a good heat insulation of the casing and that of an outlet pipe for ordered removal of combustion products makes the production process ecofriendly.