CN1195084C

CN1195084C - Filtering process of eliminating non-metallic foreign impurity ion aluminium melt

Info

Publication number: CN1195084C
Application number: CNB01139255XA
Authority: CN
Inventors: 周鸣; 孙宝德; 疏达; 倪红军; 李克; 王俊
Original assignee: Shanghai Jiaotong University
Current assignee: Shanghai Jiaotong University
Priority date: 2001-12-27
Filing date: 2001-12-27
Publication date: 2005-03-30
Anticipated expiration: 2021-12-27
Also published as: CN1362531A

Abstract

The present invention relates to a filtering process of purifying non-metallic foreign impurities in aluminium melt, which belongs to the field of casting. A stirring process is disclosed specifically as follows: a fusing agent comprising 50 wt% of NaCl and 50 wt% of KCl is stirred so as to purify commercially pure aluminium melt, the dosage of the fusing agent for one-time filtering is 300g, a new fusing agent is used for each-time filtering, the dosage of aluminium ingots is 900g, the speed of stirring is 500 revolutions per minute, the filtering temperature is controlled to be 720 DEG C, and the number of filtering times is four or more than four. The present invention which has substantive characteristics and obvious improvement can prevent molten salt added in aluminium melt from generating new foreign impurities instead of being molten, prevent aluminium melt from generating secondary foreign impurities because aluminium melt reacts with oxygen and water vapor in air, enable foreign impurities in aluminium melt to fully come into contact with fusing agents, and enable the efficiency to reach more than 84% when used for purifying foreign impurities.

Description

The method of filtration, purification nonmetallic inclusions from aluminum melts

Technical field: what the present invention relates to is a kind of method of purification to elimiante foreign impurity from aluminium melt, and particularly a kind of method of filtration, purification nonmetallic inclusions from aluminum melts belongs to casting field.

Background technology: aluminium is a kind of very active metal, and easy and steam reaction generates hydrogen and oxide inclusion (Al in fusion process ₂O ₃).These non-metallic inclusions are very big to the aluminum products performance hazards, and therefore, aluminium melt purifying is one of main path that improves the aluminium quality.Flux method remove be mingled with gas be a kind of aluminium melt purifying means commonly used, have advantages such as technology is easy, expense is cheap, therefore, it is necessary to research and develop novel degasification, impurity removing technology.The general content of inclusion in the commercial-purity aluminium is all more than 0.1%, and the size major part of inclusion all is greater than 10 microns.The international level of removing inclusion, the inclusion content in the molten aluminium is 0.02%, the size of inclusion is less than 7 microns.Flux commonly used at present has villiaumite and villaumite etc., and traditional flux treatment process is these salt to be dried with the ball milling mixing handle, and drops in the molten aluminium then.Fused salt contacts with molten aluminium, thereby gets rid of a part of inclusion, but this method can not make flux fully contact with molten aluminium, easily cause " dead angle ", even melt is stirred, also have the part melt and can't touch flux, make the effect that should have of flux be not in full use.In addition fused salt mixt is pressed into bulk, puts into the molten aluminium bottom.When fused salt melts, float to top layer from the bottom, molten flux passes molten aluminium, can remove a part of inclusion like this.But a part of salt that drops into does not have abundant mixing, and these salt can not melt under the melt temperature condition of molten aluminium, thereby form new inclusion.By literature search, people such as Fu Gaosheng are at " China YouSe Acta Metallurgica Sinica " Vol.11, No.3 Jun 2001, P433-436 writes articles, and aluminium ingot is placed on above the fused salt mixt, and aluminium drips when passing the molten flux layer when aluminium ingot melts, flux layer had both played the assorted effect of machinery retaining, strong gettering effect is arranged again, be equivalent to play filtering effect, the inclusion that contacts on aluminium melt surface with flux is removed easily.The shortcoming of this method is: because the inclusion in the molten aluminium can not carry out the long-range mass transfer, and be not easy to remove contacting that part of inclusion with flux in the middle of being rolled in molten aluminium.There are some shortcomings in this flux refining molten aluminium technology, dust removal rate is not high, exist dead angle flux fully to contact during purification with molten aluminium, aluminium drips to pass flux layer than major diameter, being rolled in aluminium drips the intermediary inclusion and can not contact with molten flux, therefore, can not give full play to flux removal of impurities effect.

Summary of the invention and embodiment: at the deficiencies in the prior art and defective, the present invention proposes a kind of method of filtration, purification nonmetallic inclusions from aluminum melts, and flux is fully contacted with molten aluminium, simultaneously non-metallic inclusion (the Al in flux and the molten aluminium ₂O ₃) chemical reaction takes place, the inclusion of moving to like this in the flux can not turn back to molten aluminium again.Method of the present invention is specific as follows: (1) use to stir the method aluminum filtration melt of flux, and molten aluminium is dispersed into tiny aluminium by flux and drips, and non-metallic inclusion in the molten aluminium is distributed on the surface that aluminium drips; (2) aluminium drops in the flux of rotation and redistributes inclusion, and the inclusion during aluminium drips is had an opportunity to be distributed to aluminium and dripped the surface and go up and contact with flux.Purify molten aluminium and can remove fine foreign matter in the molten aluminium with stirring flux method, to satisfy the high-quality aluminium of large-scale commercial production.Stirring technique is specially: stir weight percent 50%NaCL-50%KCl flux refining commercial-purity aluminium melt, filtering a flux consumption is 300g, filter each time and all be to use new flux, the aluminium ingot consumption is 900g, mixing speed is 500 rev/mins, filtration temperature is controlled at 720 ℃, filters more than four times or four times.

Below method of the present invention is further described: at first put into two plumbago crucibles in resistance furnace: a crucible is put into active flux, an other crucible is put into commercial-purity aluminium, after commercial-purity aluminium and fused salt all melt, crucible in molten aluminium is housed is put into insulating covering agent, electric blender is put in the molten flux crucible then, in stirring the flux process, divide and add molten aluminium in bulk, avoid a large amount of addings, and cause secondary oxidation, the rotation molten flux is dispersed into tiny aluminium to molten aluminium and drips, the inclusion aluminium of having an opportunity is dripped on the surface, increased the chance that molten aluminium contacts with flux, use and stir the flux refining molten aluminium, in stirring the molten flux process, divide and add molten aluminium in batches, making it be dispersed into tiny aluminium drips, and these aluminium drop in can coalescence in the rotation molten flux, coalescence and being disperseed then, can make nonmetallic inclusions from aluminum melts be distributed to aluminium like this drips on the surface, aluminium drips among the flux that is in rotation, surface that aluminium drips and flux surface constantly are updated, like this can be from the inclusion new distribution aluminium drips, making inclusion be distributed to aluminium drips on the surface, can overcome like this owing to being subjected to viscosity and capillary the influence to make inclusion can not finish the long-range mass transfer, each flux refining number of times that increases, can make molten aluminium once and again be dispersed into tiny aluminium by flux drips, thereby reappear aluminium and drip interface with flux, can make inclusion in the molten aluminium constantly be distributed to aluminium like this drips on the surface, and be attached to the lip-deep aluminium film of inclusion and washed away by active flux easily, inclusion is entered in the flux easily, thereby reach the effect of efficient impurity removal.

Stir flux method aluminum filtration melt and help realizing that from the kinetics angle inclusion the molten aluminium moves to the thermodynamic tendency in the flux, make inclusion (Al ₂O ₃) enter easily flux layer and with flux in activeconstituents generation chemical reaction.Inclusion generates new compound in active flux like this, can avoid inclusion to get back in the molten aluminium again in stirring flux.

The present invention has substantive distinguishing features and marked improvement, adopt the stirring active flux method to purify molten aluminium, the fused salt that can avoid putting in the molten aluminium does not have fusing and produces new inclusion, because the density of molten aluminium is greater than the density of flux, when stirring active flux aluminum filtration melt, aluminium drips and can sink to below the molten flux, avoid oxygen and steam reaction in molten aluminium and the air like this and produce the secondary inclusion thing, stir the flux filtration molten aluminium, can make that inclusion fully touches flux in the molten aluminium, dust removal rate can reach more than 84% in this way.

Claims

1, a kind of method of filtration, purification nonmetallic inclusions from aluminum melts, it is characterized in that stirring technique is specially: stir weight percent 50%NaCL-50%KCl flux refining commercial-purity aluminium melt, filtering a flux consumption is 300g, filter each time and all be to use new flux, the aluminium ingot consumption is 900g, mixing speed is 500 rev/mins, and filtration temperature is controlled at 720 ℃, filters more than four times or four times.

2, the method of this filtration, purification nonmetallic inclusions from aluminum melts according to claim 1, it is characterized in that following limitation of the invention further: at first put into two plumbago crucibles in resistance furnace: a crucible is put into active flux, an other crucible is put into commercial-purity aluminium, after commercial-purity aluminium and fused salt all melt, crucible in molten aluminium is housed is put into insulating covering agent, electric blender is put in the molten flux crucible then, in stirring the flux process, divide and add molten aluminium in bulk, avoid a large amount of addings, in stirring the molten flux process, divide in batches and add molten aluminium, increase the flux refining number of times at every turn.