GB2422847A - Method for fire refining of metals in the thermodynamically equilibrium system of a drip-gas medium - Google Patents

Abstract

Generally, fire refining of metals is carried out by blowing through a liquid melt thick layer and significantly rarely by mixing a melt stream with a gas. Said methods are low-productive and do not ensure rapid gas access to each melt drop. The inventive method for fire refining of metals in a thermodynamically equilibrium system consists in supplying a thin and wide metal layer to a special chamber provided with an inclined bottom and a receiver. Gases are supplied to the chamber through tuyeres embodied in the front wall thereof and through the bottom and form, together with the supplied melt, a drip-gas fog which is thermodynamically equilibrium by sufficiently heating gases and metals to temperatures which ensure a metal flowing temperature excess in a drip-gas mixture for a whole oxidizing-reducing period. Said method ensures a high productivity by rapid gas access to each melt drop and reduces materials consumption of a device.

Description

PCT 1RU2004/000427 APPLICATION SPECIFICATION

Date of filing: 28.10.2004 Applicant & inventor: MARTEMIANOV, bun Vasil'evich [RU/RU] Russian Federation, 623414 Sverdlovskaya oblast', Kamensk-Ural sky, 7 Klyuchevaya Str. [RU] Method for fire refining of metals in the temperature balanced system of a drip-gas medium.

This invention relates to methods for fire refining of metals and it is directed to obtaining metals of a defined chemical purity. The most commonly used method for fire refining of metals is blowing melted metals in a furnace bath by different gases, most often by an air (4) and the same method only with using preliminary heated air/oxidizer in recuperates by outlet hot gases (5). A process is usually divided into two phases. The first one is a melted metal deoxidation by means of blowing a deoxidizer for a long time. The second one is a recover of superoxidated metal by reductants. Besides it there is a deleting slag as before recovering as well after it.

This method is divided on deoxidation gases input to the melt surface and into the melt. The deoxidant input into the melt is more complicated but more efficient. Gases are entered through side tuyeres under the melt surface or through immersed tuyeres allowing to get gases up to the melt bottom. By this it's achieved more intensive mixing resulting in bubbling and much intensive oxidant molecules delivering into the hole melt thickness.

The more effective mixing results as a much efficient refining.

Current method drawbacks are requirements of blowing thick liquid melt layer that results in long time of blowing. But even increasing time of blowing does not result in full contact of deoxidant and reductants with most atoms of admixtures and a deoxidized metal that it's possible to make with the offered method.

It's vivid especially on a copper example. The fire refining a secondary polluted copper does not result in getting Ml copper the product desired in electrical engineering.

After the fire refining there is conducted an electrolytic copper reducing that leads to growing its price.

Besides it, long time blowing requirements lead to increasing dimensions of refining aggregates with low productivity. This grows expenses on a process conducting as compared with the inventive method.

Method of an aluminum melt treating by steams is known (3). The base of this method is CCL4 steam blowing with inert gas mixture through a plasma generator the working side of that is dipping into the melt. By this there are achieved high temperatures of dissociated steams and a process is accelerated and dipped.

This process drawback is a requirement of a thick melting layer blowing like as in common bubbling processes with dipped tuyeres.

Also a refining copper method is known (2). Vacuuming alongside with melt overheating is used in this method. It's allows to reduce gasses and other admixture density for the sake of growing copper steam elasticity. In others it is not altered from above written methods (4) and (5), and accordingly, has all drawbacks usual to them. In addition there are following drawbacks in this method. A vacuum usage limits aggregate dimensions, its productivity and caused substantial overpricing of a metal got by this method. This method considers refining a high purity copper like MO and Ml as refining is conducted by residual dispersed gases in vacuum. Refining a polluted copper requires an input a big refining gas quantity that is impossible under vacuum conditions.

The inventive method has not such drawbacks. Additionally using a metal with a raised temperature in alternative to vacuum refining pursues an object not only melt enlarging but establishing a thermodynamic equilibrium in the chamber. This allows to conduct a stable process dividing melt drops into much smaller ones almost to infinity increasing by this an active surface of a liquid metal for oxidation/recovery reactions. That allows a metal refining on two- three orders quicker and more efficiently than with above written methods.

The most like analogue of the offered fire refining method is a method (1) . It considers inputting an oxidizing gas flow under pressure with a small angle into direction of a copper containing material flow. The oxidizer injected with a pressure fractioning flow on drops, accelerates a material fall that basically has no time to react with an oxidizer, falls down on a melt mirror.

Additionally concentric positioning of tuyeres around a flow inevitably leads to differentiation drop dimensions from a circle periphery to its center that reduces process efficiency. In order to conduct oxidizing! recovering in a sufficient degree the chamber in the method (1) should be very big in a height, throughout volume of which almost impossible to support an equivalent reaction temperature. Besides it gas oxidizer streams having a big preliminary speed loose it quickly with hitting into a liquid melt flow. A fall velocity remains that is equal to melt fall velocity on that is influenced only gravity. It's inevitable with this a multiple decreasing drops breaking up on much smaller particles and it's resulted from reduced drops blowing because of their fall regulating. That's why a simple mixing process described in (1) caused only a partial melt breaking into small drops retaining most part of drops much larger. Accordingly a metal inside big drops has no chance to react with gases.

The inventive method hasn't such drawbacks. Gravity forces are used in it completely as well as gases and melt counter flow scheme with homogeneous dropping of input thin metal layer. Gas elasticity met melting allows to keep material drops in an atomize mixture influence zone as long as needed for a full reaction in a compact chamber. While falling lower drops meet a gas pressure from below, decelerating and colliding with upper drops dividing inevitably on small particles up to smallest that enlarging a total melt surface for reacting with gases up to impurity and allowing achieve refining metal required.

The aim of the invention is most quick delivery deoxidizing and restoring atoms to max possible refining metal atoms. On the base of it there is carried out most completed deleting admixtures from a melt metal and timely separating reprocessed slag from refining process. Solving this problem allows to reach the aim of the invention unlike the analogous.

The invention aim is achievement of required metal purity e.g. getting needed quality without additional cycles of reprocessing. In particular under fire copper refining it is possible to get Ml copper according to GOST RF 85902001 with a total content of Cu and Ag equal to 99.90% of a product required for electrical engineering without additional electrolytic refining.

A main condition for stability of an offered process is a temperature balance in fire refining chamber.

Inputting oxidizers and restorations shouldn't be simply heated but heated to temperatures that prevent for sure from premature cooling the refining melt metal. Total heating got with input substances and from an oxidation shouldn't be less than total heating lost by melt at the same time.

The most favorable temperature of input substances should not be less then melting temperature of a refining metal.

Such temperature balance will allow breaking up a refining metal on smallest drops and mixing it with input oxidants and restorations in weighted conditions bringing gas/drops mixture to thick smog. By this there is provided enough time for drop passing through this atomized smog.

A tight contact of gases and metal drops allows to accelerate the refining process up to several times and to grow substantially admixtures deleting into slag and fumes. A correlation of mass input a thin metal layer per second and correspondent gas/drops mixture pillar volume are differ not less then three orders. Gases will react on each small drop surfaces that permanently breaking up till outlet from elasticity gas zone acting. Proceeding from it the theoretically possible limits of admixtures deleting becomes more achievable. The limits base on thermodynamic analysis of their behavior like with oxygen.

For example, in the offered method a minimal copper concentration is much less than actually achieved in currently used processes. It should be noted that an admixture concentration value in slag is an important influence factor on a process chemical reaction. Additives and fluxes are considered for substantial decreasing this factor. If process temperatures are not high enough that leads to decreasing liquid metal fluidity and sharp worsening drop breaking up as well as to deterioration reaction efficiency.

The temperature balance is a condition for melt drops breaking up alongside oxidizing/reducing of each drop surface leading to effective reactions conducting and it's an essential sign of the inventive method.

The metal intended for refining is delivered as a melt from a furnace or a ladle 1 into a special refining chamber 6 shown on the scheme. Under a continuous process a metal may be delivered through a mixer.

From a vessel with a melt a metal is directed into a chute groove 2. The chute is made as wide as a chamber breadth. A metal flow is getting to the chute groove overfilling it and by a wide thin layer draining to the chamber 6. A screw 3 is adjusting a graining metal layer thickness.

A liquid metal while falling down from the whole wideness of the chute meets gases supplied from side tuyeres 4 positioned in two rows in a staggered order. The metal offset drift into the chamber depth is adjusted by a pressure in side tuyeres. It's possible to change the process duration in the chamber by this mean.

The chamber bottom is made with a slope.

That's why gas influences from bottom tuyeres 5 (also positioned in staggered order) on metal drops under equal pressures grade proportionally to a slope.

After falling on the bottom a metal drains off into a pit 9 where is spalling with a slag formation.

The slag through a fencer (not shown on the scheme) is removed periodically.

If needed a wall is constructed in the pit, the wall doesn't reach the bottom. In that case a metal would get into the chute only after sediment (from the bottom) but the slag would be separated by the wall (the wall not shown on the scheme as the chamber may be produced without it).

Gases are input into tuyeres with temperature that needed for supporting a temperature balance in the chamber. If needed some additives are used with gases in dust or melted forms.

Gas heating is carry out by the recuperate systems. Final heating is conducted by plasma generators. Through it gases are partially dissociate on ions and become more active.

Exhausted gases are going out through the output port 7. Hot gas circulation is possible with oxygen and additives replenish and excess gases discharge.

Depending on type of a metal refining it would be needed two chambers if there is no possibility to align oxidizing and restoration processes. One chamber is used for oxidizing and a second one for a metal reducing.

Under quick metal oxidizing and its reducing as well as there is no importance in slag deleting before reducing these processes can be aligned in the one chamber. For this it's required to make the chamber longer and separate bottom tuyeres rows on some banks. Thereafter oxidizing gases with additives should be input into first banks and reducing gases into followed ones also with additives needed.

As a result an offered method has some advantages to compare with analogous. They are: 1. Refining is accelerated several times due full mixing of small drops with oxidizing and reducing gases and dust/melted additives also admixtures deleting becomes better on the order having a stable process while observation of temperature balance.

2. Refining process is controlled easily due using side tuyeres with an adjustable blowing mode. Also it's possible to change blowing modes in bottom tuyeres.

3. Aggregate material intensive is decreased substantially to compare with current methods.

References 1. GB 1165514 (THE BRITISH IRON AND STEEL RESEARCH ASSOCIATION) 01.10.1969, Claim 1.

2. US 248224 (L.A.Goutiv at all) 16.12.1969, Claims.

3. V.L.Naydek, A.V.Narivsky, "Refining process of aluminum melts by gas reacting media" "Metal and Casting in Ukrain" magazine, 2004 # 1-2.

4. V.A. Aglitcky "Pyrometallurgical copper refining", M. Metallurgy 1971. pp.18 8-197 5. V.A.Kozlov, S.S. Naboychenko, B.N.Smirnov, "Copper refining" M. Metallurgy 1992.

pp.40-44.

Claims (1)

1. We claim: Method for fire refining of metals comprising using a special

   chambers provided with tuyeres for hot gases supply, in which method a thin layer of melted metal is supplied to said special chamber downward against gases supplied through tuyeres upward, the melt being continuously breaking up to drops, gases together with drops of melt forming a thick drip-gas fog which is temperature balance by sufficiently heating gases and metals to temperatures which ensure a metal flowing temperature excess in a drip-gas mixture for a whole oxidizing-reducing period.