DE2136686A1 - Apparatus and method for vaporizing liquids - Google Patents

Description

COPPER EEi ¹ IUERIES PTY. LIMITED, Townsville, Queensland,

Australia

Device and method for vaporizing liquids.

The invention relates to a device for vaporizing Liquids to concentrate them and remove the substances dissolved in them. The evaporation of liquids can either only be used to concentrate, purify or condition the liquid or only to recover the dissolved liquid Substances or also serve for the two purposes mentioned above.

The invention is generally applicable to the evaporation of Liquids for the purposes indicated above. However, the invention is particularly advantageous for the treatment of a Electrolytes, such as those used in the electrolytic refining of copper is used. So it is possible with the invention to recycle the electrolyte for reuse and the to recover economically important substances, which due to their uninterrupted use in the refining of Accumulated copper in the electrolyte. The invention will hereinafter be described mainly on the basis of the above

109885/1736

advantageous application example explained. However, the invention is not limited to a treatment of an electrolyte.

In the electrolytic refining of copper is the one mainly used Electrolyte a solution of sulfuric acid and copper sulfate. The copper anodes usually contain nickel as an impurity, in the order of magnitude of less than a 56 lies.

This nickel content is naturally exposed during the electrolytic migration. However, if the nickel from the If the electrolyte is not removed, it will build up and the copper deposited on the cathode by inclusion of the Increasingly contaminate electrolytes during the deposition process. The concentration of nickel in the electrolyte must therefore be kept at a sufficiently low value so that the proportion of nickel in the cathode copper is one does not exceed an acceptable value, for example 2ppm. The electrolyte naturally also contains a number of other soluble impurities, such as arsenic, iron and calcium, which are undesirable in the electrolyte and can be removed together with the nickel or even before the nickel is removed. However, below will mainly dealt with the nickel content, since the recovery of nickel in the form of NiSO. of considerable, more economical Meaning is.

To the extent that the invention is used in connection with the electrolytic refining of copper, it is therefore an aim and purpose the invention,

a. to refine the copper effectively, b. to sell a significant nickel by-product in a more effective way To gain form and c. The objectives listed under (a) and (b) in a way and with a device to achieve that compared with the previous one

109885/1738

2136689

State of the art simply s ± ü and one have high efficiency.

Purification of one electrolyte generally involves two Stages.' In the first stage, the copper and arsenic are removed electrolytically or in some other way. The first stage thus prepares the. Electrolytes for the second stage, i.e. for the concentration process on which the invention is based relates. The liquid fed to stage 2 consists of a solution of sulfuric acid, nickel sulphate, iron sulphate, Calcium sulfate and small amounts of other materials.

The task of the cleaning process is to reduce the concentration of foreign substances in the material used for electrolytic refining To keep electrolytes below an acceptable level. The foreign substances can for example be Mckelsulfat which is valuable but undesirable in the electrolyte. Since the concentration of foreign substances in the electrolyte is only below needs to be kept at a still acceptable value, only a sufficient part of that is used for refinement Electrolytes, are cleaned, leaving just enough impurities is removed, as with fine impurities. It is an essential feature of the invention, that the cleaning device due to its efficiency compared to known cleaning systems in terms of reliability small, can be built. In a trial use the cleaning device according to the invention was found to have a satisfactory concentration of foreign substances with a continuous withdrawal of 13.6 1-min (3 galsmin) from a total pump turnover of 735o 1-min (162o gals-min) was not exceeded.

The cleaning cycle is parallel to the refining cycle switched sub-circuit. The cleaning cycle has one Inlet line leading from the outlet line of the refiner

109885/1736

Circuit located pump branches off. Furthermore "owns" the cleaning cycle an outlet line through which the purified electrolyte is returned to the inlet line, which returns to the pump in the refining circuit.

In every second stage of the cleaning process, the electrolyte is heated to remove excess liquid Concentrate water and the salts dissolved in the electrolyte in a state of a saturated solution bring so that, after a subsequent cooling, the dissolved salts are removed in a satisfactory manner. The crystals are partly precipitated in the evaporator and partly during the subsequent cooling process. the Crystals can thus be removed. The concentrated liquid from at least the most harmful impurities is freed, can then be fed to the refining cycle for repeated use.

On the basis of the above, one could come to the conclusion that the cleaning process in the second stage represents a relatively simple method. However, this is not the case. The evaporation of such liquids represents has long been a serious problem in the industry and many different stopgaps have been made in the past tried, but so far none of these stopgaps are entirely satisfactory, although they are widely used. It is therefore the aim and purpose of the invention to eliminate the previous shortcomings.

In the case of a generally customary cleaning in the second stage a conventional tubular heat exchanger is used, which is heated with the aid of steam or heated gases. Such Tubular heat exchangers are satisfactory up to a point, but they become due to encrustation

109 085/17

~ ⁵ ~ 213668

quickly ineffective, the main work "with these tubular heat exchangers "is that the heat exchanger surfaces must be kept clean with those to be treated Liquid comes into contact. Keeping the heat exchanger surfaces in line stands in the way of continuous operation.

Another commonly used method is that the solution is poured into heavy steel or cast iron pans heated with the help of an open flame under the pan. However, this method has the same disadvantages with itself, which have just been set out in connection with the tubular heat exchangers. In an effort to address these disadvantages To avoid it, it has been proposed to introduce hot gases into the solution in order to transfer the heat directly to the solution. However, this direct heating method requires the use of nozzles or similar devices, which are described in immerse the solution, or use other devices that introduce the hot gases into the solution. With With this method, however, it cannot be avoided that solid sulfates are deposited on the nozzles or similar devices or apply similar precipitation. The great local heat to which the incrustations are then exposed leads to the fact that the sulfates, for example nickel and iron sulfates, disintegrate and release sulfur trioxide. This sulfur trioxide escapes into the atmosphere, where it is an extremely harmful pollutant. The most serious effect the known method is therefore that the the evaporation system leaving hot gases pollute the air and pose a serious disadvantage.

Another disadvantage of the known methods is that the damming that occurs at the heat exchangers is one have a detrimental effect on the thermal efficiency, as an insulating layer of salts attaches itself to the heat exchange

109885/1736

~ ⁶ ~ 2136886

surfaces. This leads to a low efficiency of the Heat transfer with the result that the exchange medium is excessively heated and with the H «SO located in it. receives a response. If the salt layer as well as the salt layer and the enclosed H «SO. further about the decay temperature are heated, as has already been shown, sulfur trioxide is inevitably produced.

It is therefore a further object of the invention to achieve those outlined above Avoid disadvantages with the help of a method and a device which have a high thermal efficiency have and. the release of sulfur trioxide or other pollutants into the air to a value that is reduced in Is acceptable in terms of air pollution prevention regulations and laws. At the same time an extraction of substances such as Kiekelsulfat and / or an effective removal of other impurities is possible be made.

Another advantage of the invention is that cleaning in the second stage during the electrolytic refining process can be carried out and that purification the first stage of the electrolyte in the refining process takes place.

The invention relates in the broadest sense to a method for evaporating a liquid and for removing in the Liquid solute, which is a fuel burned in a closed chamber with an open bottom with the bottom edge being below the surface of the liquid so that the combustion products are direct are introduced into the liquid, and in which the inner surfaces of the chamber by the application of a cooling medium on the outside of the chamber are cooled and flushed sufficiently so that the inside surfaces of the

109885/1736

Chamber settling particles are rinsed off, and at which the solids precipitated in the liquid are removed.

In the following, an embodiment of the invention is based on explained in more detail by drawings. In the drawings show i

Fig. 1 is a plan view of a combustion chamber

FIG. 2 is a cross-section through a combustion chamber taken along line 2-2 in FIG. 1

3 shows a side view of a system with combustion chambers immersed in a liquid.

As can be seen from the drawings, a combustion chamber 1 is surrounded by a jacket 2. The combustion chamber 1 ends in a collar 3 in which a plurality of slots 4 are provided. A mounting flange 6 attached to the outside of the water jacket 2 is used to attach the chamber 1 to a tank described below. The chamber 1 is covered with a cover 7. An air distributor 8 is arranged on the cover 7. A refractory spacer 9 holds a fuel stone from the cover 7 at a distance. The fuel stone 1o is connected to an oil burner 11. Below the cover 7, a steam spray ring 12 is arranged, from which a plurality of steam nozzles 13 protrudes. The chamber 1 can be partially immersed in the liquid so that the liquid in the K _a mmer 1 to a liquid level

14 increases.

That used to flush the inner surfaces 15 of the chamber 1 The medium can be water, which directly hits the surfaces

15 is sprayed. However, the medium is preferably steam, which emerges from the nozzles 13 and a film-like flow of water through condensation on the cooled inner surfaces of the chamber 1 "forms, which runs down the walls and as a solution

109885/17 36

agent or separating layer acts that prevents itself. Solids in the form of incrustations settle on the surface. The addition of rinse water increases the amount of water to be evaporated, so that the required value of the Concentration of the liquid is maintained. the end For this reason it is advisable to apply the flushing medium sparingly, for example by blowing the steam out intermittently in short bursts and against the walls of the chamber is judged.

In an exemplary embodiment according to the invention, the Chamber 1 has a cylindrical wall, the open bottom of which ends in a collar 3 which is immersed in a liquid, which is subjected to purification in the second stage. The burner 11 is supplied with any suitable liquid fuel, such as diesel distillate, which is supplied with the help of suitable nozzles together with that for combustion required air is injected into the burner. Since the fuel is liquid, it can be adjusted below Conditions are burned off so that the 'products of combustion are free of. Are oxygen and ash. The coat 2 is a coolant, such as water supplied, which by means of a suitable. Pump is continuously circulated, which receives the water from a cooling tower or the like.

The degree of circulation of the cooling water is preferably adjusted so that the walls of the chamber are kept at one temperature at which the outlet temperature of the cooling water does not exceed 85 °. The warmth of the exiting Cooling water can, advantageously, be used in a heat exchanger from the first cleaning stage exiting liquid is preheated on its way to the second stage in a countercurrent process. The lid of the combustion chamber can be cooled with water in the same way as was done in connection with the walls of chamber 1

109885/1736

2136688

■ was described. However, the lid is advantageously cooled by the fact that the air distributor 8 acts as a line for preheating the air required for fuel combustion is used.

The steam can enter the chamber in several different ways 1 can be submitted. Advantageously, however, the tubular The spray ring 12 for the steam is attached directly below the cover 7 in the chamber 1. The outside diameter this ring is expediently almost equal to the inner diameter of the chamber. The steam is the ring of any conventional source. The ring 12 is provided with a plurality of nozzles 13 through which the Steam is directed against the walls and lid of the chamber. The nozzles are at a sufficiently small distance from each other arranged to ensure that the curtain of condensate formed on the inner wall of the chamber has one around the entire circumference running, coherent film forms before the condensate curtain reaches the bottom edge of the container, which is in the immersed the liquid to be treated. The steam supplied is saturated steam with a nozzle pressure of about 7 at.

The tank, which holds the liquid to be treated, expediently has a capacity of 2o5o liters. (45o g sharp). The amount of liquid supplied to the tank is about 13.6 1 min. The chamber 1 preferably has a height of about 50 cm and a diameter of 66 cm. Under these conditions, a suitable amount of steam is intermittently in the chamber Enter the form of short bursts, each burst lasting about a minute and between two consecutive bursts Bumps lie about 2 hours.

The collar 3 of the chamber preferably has a plurality of slots or has a sawtooth-like shape _f so that the combustion gases in the form of many small jets into the

109885/1736

Liquid enter. This avoids excessive turbulence in the liquid. Advantageously the collar 3 immersed in the liquid is surrounded by an annular channel 5 on its underside is open and its outer circumferential wall is slotted or sawtooth-like in the same way, uia to achieve a greater number of outlets through which the combustion gases are directed into the liquid.

Operation is preferably continuous at a constant Concentration of the liquid is carried out so that the amount of liquid supplied just matches the amount of the evaporated water and the drawn off, concentrated liquid is in equilibrium. In practice this will be achieved in that the liquid is supplied continuously and the concentrated liquid is withdrawn intermittently so that the liquid level in the tank fluctuates between an upper and a lower limit. With a preferred one Working process, the concentration of sulfuric acid is kept above the value at which the steel parts be attacked by corrosion.

When the salts that precipitate in the liquid, with the help are moved intermittently by suitable scrapers or stirrers and a drive 2o, the salts can be kept in solution and removed together with the concentrated liquid will. The hot, saturated solution and the precipitate from the liquid are then cooled, whereby the major part of the salts to be removed is precipitated. The hydrated liquid is then settled or filtered or the like separated from the precipitated salts, whereupon the purified liquid is returned to the inlet line which leads to the refining cycle.

109885/1736

As can be seen in FIG. 3 , a tank 16 contains a liquid 17 which rises to the liquid level 14. The liquid to be cleaned is fed to the tank 16 via an inlet line 18. The inlet line 18 is arranged in the vicinity of the tank cap. The concentrated liquid is drawn off from the tank 16 via an outlet line 19 which is arranged near the bottom. Devices can also be provided which ensure that the level of the concentrated liquid in the tank 16 is kept essentially constant and is kept above the height, The tank 16 has a cover plate 21 on which a plurality of chambers 1 are fastened with the aid of the mounting flanges 6. In the present case, three chambers 1 are fastened on the cover plate 21. Each of these chambers , is inserted into an opening of the cover plate 21, which is equipped with a chimney or the like for receiving the exhaust gases after the gases have bubbled through the liquid 17.

Zi / TJl

- patent claims -

109885/173 6

Claims (10)

PATENT CLAIMS 1. Process for evaporating and thickening a liquid and for removing substances dissolved in the liquid, characterized in that a fuel in a closed Chamber with an open bottom is burned and that the bottom edge of the chamber is below the surface of the liquid, so that the products of combustion be introduced directly into the .Liquid, and that the inner surfaces of the chamber by applying a Coolant on the outside of the chamber are cooled and flushed sufficiently so that the Solid particles settling on the inner surfaces of the chamber are rinsed off, and that precipitated in the liquid Solids are removed. 2. The method, emizeichnet according to claim 1, characterized Ge that used for rinsing the interior of laughter, the medium is water chamber 1st "which a.us steam has arisen by KoB.densa.tiOn. at. A film-like stream of water "forms" on the cooled interior surfaces of the chamber, which runs down the walls and acts as a solvent or separating layer which prevents the build-up of solid particles on the interior surfaces of the chamber. 3. Device for Biirclifulirtiiig of the method according to one of claims 1 or 2 ₉ characterized by a chamber with a ¥ aad ₉ a lid and an open bottom, \ uobei the bottom in © ine liquid © intauolrb and the lid a through, ifenhindurchführung refractory line has and the refractory line with nozzles for injecting a fuel and the sur burning of the fuel required. Air is provided. 109885/1736 4. Apparatus according to claim. 3, characterized in that the chamber walls and / or the cover are provided with a jacket in which a coolant is circulated around the chamber. 5. Apparatus according to claim 4 »characterized in that a tubular, ring-like steam distributor in the chamber is arranged directly below the cover and the outside diameter of the distributor approximates equal to the inside diameter the chamber is and that means for supplying "the steam from a steam source to the steam manifold." are provided and that the distributor with a variety is provided by outlet nozzles through which the steam is directed outwards against the walls and the lid of the chamber will, and. that the nozzles are spaced sufficiently close to each other to ensure that a The condensate curtain formed on the inner wall of the chamber takes the form of a continuous one running around the entire circumference Before the condensate curtain reaches the bottom edge of the container, the film in the container to be treated Immersed in liquid. 6. Apparatus according to claim 5, characterized in that the edge of the container bottom is slotted or sawtooth-like is designed so that the combustion gases into the liquid in the form of many, small jets can penetrate in order to reduce the turbulence in the liquid and that the edge immersed in the liquid is surrounded by an annular conduit that is open at the bottom is and the outer peripheral wall slotted in the same way or is sawtooth-like to form further outlets through which the combustion gases into the Liquid can be conducted. 10 9885/1736 Device according to one of Claims 3-6, characterized in that that the liquid is contained in a tank that holds the liquid to be cleaned in the vicinity of the Tank cap and which has a drain line for the concentrated liquid in the trouble of the bottom, and that devices are provided which the "liquid level the concentrated liquid essentially keep constant, keeping the liquid level above the level at which the combustion gases are emitted, and that the tank has a cover plate which separates a plurality of chambers from one another, and that the cover plate has an opening which is used to receive a flue for sucking off the exhaust gases after the exhaust gases have bubbled through the liquid. «8B5 / 1736 Blank page