DE1164677B - Process for the production of electrolyte iron - Google Patents

Description

Method of Making Electrolyte Iron The invention relates to a process for the production of electrolyte iron by electrolysis from copper-containing Pig iron and at the same time for the separation and recovery of gold, silver and Copper.

Processes for the electrolysis of iron are known per se and some are have found industrial application. The known processes are refining electrolysis and the extraction electrolysis. However, these methods have the following disadvantages.

In refining electrolysis, carbon steel is commonly used for the anode used. The carbon inside the anode becomes an insoluble matter of very fine grain size that goes into suspension in the electrolyte and on which Iron adheres to the cathode and contaminates it. There are also various impurities and iron hydroxide, which form an additional turbidity, all precipitates of finer proportions Grain size, which cause cloudiness in the electrolyte and adhere to the cathode, whereby their quality is reduced. To solve this problem, measures were taken like using a membrane or filtering the electrolyte. In all of these cases, however, difficulties arose from constipation due to the very fine iron hydroxide particles. When using a diaphragm there is an increase in voltage the consequence, while in the case of filtering this becomes difficult. Measures of the mentioned Art therefore all involve considerable difficulties and high costs. When producing high quality electrolyte iron by ordinary refining electrolysis therefore, various restrictions on the raw material are inevitable. The need to use a low carbon steel as a starting material is a particularly serious disadvantage.

There are some reports on the manufacture of electrolyte iron from high purity has become known through extraction electrolysis. However it is too In this process it is necessary to completely dissolve the iron in the electrolyte bring about and - chemically and physically - ions of metals, which are more noble than iron, ions which are detrimental to electrolysis, insoluble Completely remove residues and other undesirable substances. Furthermore is it is difficult to carry out this process in an economical manner, especially because of the high power required for the electroiyse.

Because of the disadvantages of the conventional methods described above It is a main object of the invention to provide a new method for Production of high-quality electrolyte iron, in which the disadvantages mentioned are eliminated or are reduced.

Another object of the invention is to provide a method of the kind mentioned, this in an economical manner by a simple electrolysis process can be carried out.

The foregoing and other objects and aspects of the invention result from the following description of the method according to the invention, which essentially is that a refining electrolysis of copper-containing pig iron under Use of a Mohr's salt solution with copper, known per se as an electrolyte as an effective anode contaminant to produce electrolyte iron and at the same time separating and recovering materials such as gold, silver and copper. In particular, pig iron containing copper is obtained by the process according to the invention used, for example of the kind that occurs in reduction melting e.g. B. from Dry zinc slag is obtained after the zinc is removed from this in the form of dust Has been recovered using a refining electrolysis with the help of a Mohrschen Salt solution is carried out with the copper-containing pig iron as the anode, whereby Electrolyte iron is extracted at the cathode.

The details of the invention and the manner in which its objects can best be achieved will be apparent from the following description which begins with a consideration of the copper-iron state diagram. Since copper forms a solid solution in iron up to an amount of 0.4 to 0.5 per cent at room temperature, if the copper content is between 0.5 and 2.50 per cent, the copper in excess of 0.501 per cent will be added to the Precipitated grain boundaries of iron. Indeed, microscopic examination of the pig iron anode reveals a network of shiny brass color at the pearlitic-crystalline grain boundary. Since copper is electrochemically a more noble metal than iron, it does not go into solution when the electrolysis of the iron is carried out, but remains unchanged in the anode. That is, only the iron goes into the electrolyte, and the copper remains unchanged in the state of a network on the anode surface, whereby it appears as if a fine-meshed membrane were enveloping the anode. This network shell holds back the insoluble constituents, such as carbon and silicon, in the pig iron from entering the electrolyte. If the copper content within the iron is 2.5 to 3% or higher, the resulting structure according to the phase diagram would be such that a solid solution of copper is precipitated at the grain boundary of the eutectic crystal. However, if there is sulfur in the starting material, a copper stone forms, which separates from the pig iron. In this case it is therefore unlikely that the copper content in the Robeisen will be greater than 2.5 to 3%.

The copper precipitated in the form of a network at the iron grain boundary is present together with iron in the electrolyte and forms a local one with it electric cell. Therefore, if the copper content in the pig iron were 0.4 to 0.5 per cent is or higher, the solubility of iron may be higher than in the case in which there is no copper. The solubility of the anode is therefore increased.

By the method according to the invention, by which the described It is possible to use a high-quality electrolyte iron obtained by a simple electrolysis process, d. i.e., those contained in the anode Copper component is used as an impurity, creating the beneficial effect increasing the solubility of the anode is achieved, so that the generated sludge Assumes a laminar shape and at the anode with ample porosity for passage of the electrolyte adheres, but with a suitable strength so that it does not falls off easily. The electrolysis can therefore take a very long time favorable conditions when using pig iron or naturally high carbon Steel to be continued.

In order to explain the exact nature of the invention in more detail, Below are some examples with further details of the respective conditions given.

Example 1 Electrolysis was carried out under the following conditions.

Composition (percent by weight, unless otherwise stated) of the anode: 1.53 C, 0.25 P, 0.39 S, 2.22 Si, 0.74 Mn, 2.55 Cu, 233 (g / t) Ag, - Au, 0.055 In, 91.3 Fe. Electrolyte: Mohr's salt solution (Fe SO4 - (NH4) 2 SO4 - 6 H20); Fe concentration 51.1 g / l; pH 3.0 to 5.4. Current density: 1.25 A / dm2.

Electrolyte temperature: 60 ° C.

Electrolysis duration: 23 days.

Distance between electrodes: 50 mm between the opposing electrodes Areas of the anode and the cathode. Electrolysis voltage 0.8 to 0.83 V.

The compositions obtained (weight percent unless otherwise specified) of the electrolyte iron product and the slurry were as follows: Example 2 The electrolysis was carried out under the following conditions: Composition (percent by weight, unless otherwise stated) of the anode: 1.60 C, 0.098 P, 0.18 S, 1.96 Si, 1.65 Mn, 1.56 Cu , 195 (g / t) Ag, - Au, 0.049 In, 87.0 Fe. Electrolyte: Mohr's salt solution (Fe S04 - (NH4) 2S04 - 6 H20); Fe concentration 50.0 g / 1; pH: 3.0 to 5.4. Current density 1.00 A / dm2.

Electrolyte temperature: 60 ° C.

Electrolysis duration: 26 days.

Distance between electrodes: 60 mm between those facing each other Areas of the anode and the cathode. Electrolysis voltage: 1.0 to 1.2 V.

The compositions obtained (weight percent unless otherwise specified) of the electrolyte iron product and the slurry were as follows: Elements electrolyte iron sludge C 0.001 - P 0.010 0.41 S 0.002 - Si 0.002 (max.) 7.32 Mn 0.003 - Cu 0.007 6.49 Ag - 772 g / t Au - 6.0 g / t In - 0.19 Fe 99.9 27.4 In the previous two examples 1 and 2, there was almost no change in the electrolytic voltage, the current efficiency was indicated as 95 to 980 / , the deposition was good, the electrolyte underwent changes in a clear state throughout the process, and an electrolyte iron with a white metallic luster was obtained on the cathode. After 23 to 26 days of electrolysis, the amount of sludge adhering to the anode was shown as 90% of the total amount formed, while the sludge settling in the electrolysis tank was only 10% of the total amount. The anode retained its original shape after the electrolysis was complete, but after the sludge was peeled off, the anode was observed to have dissolved uniformly and a very slow rate of erosion was indicated.

It can be seen from the preceding examples that by electrolysis of iron containing 0.5% or more copper, as described, by the process according to the invention, electrolyte iron can easily be produced and copper, gold, silver and other substances can be separated and recovered at the same time Excellent results were obtained especially in the case of a copper content of 1.1 to 2.5%. Example 3 For comparison with the previous examples, electrolysis of carbon steel was carried out under the same conditions. The results were as given and described in the table below (data in percent by weight, unless otherwise stated). Elements anode electrolyte sludge iron L C 0.60 0.021 0.63 P 0.03 0.009 - S 0.03 0.008 - Si 0.007 0.002 0.6 Mn 0.30 0.006 - Cu 0.055 0.006 4.8 Fe balance balance 57.0 Although the electrolysis conditions were the same as in the previous examples, the sludge was in powder form, easily fell off and formed into a suspension, the dissolving action was irregular, and the electrolysis could not be continued for a long period of time.

After 5 days of electrolysis, the amount of sludge adhering to the anode was only 420/0 of the total amount formed, while 580 % of the sludge fell off or formed a suspension in the electrolysis tank. In addition, the opacity of the electrolyte increased over time.

From the foregoing it can be seen that the method according to the invention a number of advantages over the traditional method of making electrolyte iron by refining electrolysis. The main advantageous features of the invention Procedure can be summarized as follows: 1. The dissolution of the anode is uniform and the removal rate is low.

2. There is no increase in voltage due to the increasing thickness of the Mud layer.

3. Since the solubility of the anode is high, there is almost no oxidation of the electrolyte instead.

4. The process of recovering the sludge is simple.

5. The sludge does not fall off with the formation of a suspension in the electrolyte, so that measures such as distillation of the electrolyte to remove it suspension or the use of a membrane for dialysis is not required are.

6. There is no contamination of the electrolyte iron by free powdery sludge instead, which is made up by ordinary electrolytic refining Mild steel is formed.

Claims (1)

Claim: Process for the electrolysis of copper-containing pig iron for the production of electrolyte iron and for the simultaneous separation and recovery of substances such as copper, gold and silver, using a Mohr's salt solution (FeS04 - (NHJ, S04 - 6 HGO) as electrolyte, characterized in that a refining electrolysis is carried out by copper-containing pig iron, which is 1.1 to 2.5 per cent. copper and 1.0 contains up to 2.4% carbon, the copper contained being an effective anode impurity is used. Referred to U.S. Patent No. 2,626 895.