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Contenido archivado el 2022-12-27

DEVELOPMENT OF A COMPACT LINE OF EQUIPMENT FOR THE RECOVERY OF ALUMINIUM BY DROSS COMPRESSION

Objetivo

The aim of the project is to optimize energy wise an existing industrial process for the processing of dross skimmed from aluminium casthouse furnaces.
The COMPAL process offers two major advantages from the energy point of view :
- immediate recovery of the liquid metal occluded in the dross, with no need to remelt in a furnace,
- a higher metal recovery rate owing to the rapid compression of the hot dross immediately after skimming from the furnace.
The improvements made to the COMPAL installation, which culminated in the "COMPACT V.A.W. COMPAL 350" concept, are summarized in the following chart.
COMPAL PROTOTYPE COMPACT V.A.W.
1ST GENERATION COMPAL 350
Floorspace 149 m2 62 m2
Overall cycle time 25 minutes 13 minutes
Capital expenditure 9110 KF 6571 KF
. LENGTH OF ONE COMPRESSION CYCLE
From January 16 to 22 1991, our partner V.A.W. carried out a campaign of compressions under industrial conditions.
87 compression cycles were carried out.
The average compression cycle takes 11 minutes.
. RECOVERY RATE OF THE ALUMINIUM CONTAINED IN THE DROSS
3 campaigns of tests were conducted with modifications of the compression process parameter between each campaign.
During these three campaigns of compression tests, we encountered immense difficulty in the processing of the dross from the V.A.W. casthousefurnaces.
The particularly uncommon aspect and texture of the dross prevented us from reaching the expected rates of recovery, which we had achieved with the COMPAL prototype using other types of dross.
The reactivity of aluminium with oxygen causes melt losses by the formation of drosses in all cast houses and foundries. Although the amount of dross produced varies for different operations, in all cases a large amount of non-oxidised aluminium is contained in the dross. Traditionally, partial recovery of this aluminium is achieved by cooling and crushing the dross and remelting the coarse fraction under molten salt. The main disadvantages of this method are its high energy requirement and the production of considerable salt residues which, because of their solubility in water, are difficult to dump safely. In this project, the extraction of the metal is achieved by compressing the hot dross immediately after it has been skimmed from the furnace.
The equipment consists of a 235 ton 4-column press with a 350 litre container. The basic operation of the plant is as follows; the dross container is pre-heated to 800 deg.C by gas. The hot drosses are fed into the dross container whichis then transferred under the press. The hydraulic press squeezes the aluminium out of the drosses and this is collected in an ingot mold. After compression the container is raised, along with the press, and the remaining dross cake is discharged and dumped. The cycle time is 15-20 minutes.
Apart from the energy saved, other advantages of the project are an increased aluminium recovery yield and considerable reduction in the amount of waste to be dumped.
In the case where the texture of the slag emitted by the smelters permits compression, a seven-month follow up period of the quantity of metal recovered and of the energy consumption should establish the success of the project in comparison to conventional treatment methods.

Convocatoria de propuestas

Data not available

Régimen de financiación

DEM - Demonstration contracts

Coordinador

Aluminium Pechiney
Aportación de la UE
Sin datos
Dirección
Centr'Alp
38340 Voreppe
Francia

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Coste total
Sin datos