DE1116693B - Process for processing iron ore - Google Patents

Description

Process for processing iron ore Poor iron ores are available for processing not desirable in blast furnaces. But they can be enriched to produce ores, which are richer in iron oxides and therefore more suitable for blast furnace purposes. The main ones Components that are separated for the purpose of enriching these low-value ores are the oxides of silicon, aluminum, calcium, magnesium and phosphorus. Removal of sulfur is also desirable.

A well-known enrichment process consists in the ore in which the iron must be in ferric form, with aqueous hydrochloric acid to form to treat a solution containing ferric chloride and this chloride by distillation to win in the presence of hydrogen chloride.

According to the invention, substantially all of the ore is contained Iron is converted into a solution of ferrochloride, which is in solution among other elements contains either aluminum or phosphorus or both with or without calcium and which The acidity of the solution is so decreased that aluminum or phosphorus or both are precipitated will. Aluminum is deposited in the form of hydroxide or phosphate. at Absence of enough aluminum can precipitate phosphorus as calcium phosphate will. Any ferric iron in the solution may reduce the acidity also precipitate in the form of hydroxide or phosphate. The solution is provided by the insoluble substances separated and the ferrocbloride contained in it in ferro- or Ferric oxide converted.

Compared to processes in which the iron is in ferriform form, the inventive method has the advantage that ferrous chloride is relatively easily crystallized, while it is almost impossible to crystallize ferric chloride, When working under ferrous conditions it is possible to use phosphorus and aluminum as Separate phosphate while the iron remains in solution, It can be from an ore be assumed in which most or all of the iron is in ferric form, z. B. from a weathered ore that contains ferrocarbonate. Alternatively, from an ore can be assumed that contains most of the iron in the ferriform. Then the ferric iron must be reduced before the pH rises to a value at the Ferrieisen is knocked down. This reduction can be achieved through pretreatment of the ore are carried out, the ferric oxide z. B. by hot reducing Gases is reduced to ferrous oxide.

In general, however, it is in the treatment of an ore in which the iron is mainly in the ferric form, more expediently the reduction in the solution. Such a treatment in solution can be achieved by adding metallic Iron take place, e.g. B. in the form of steel turnings or sponge iron or iron ore (which can form part of the original ore) that leads to the metallic state has been reduced to ferric chloride to ferrous chloride according to the reaction 2 Fe Cis -I- Fe = 3 Fe C12 to reduce.

When performing the invention; Process becomes aqueous Hydrochloric acid, the concentration of which is e.g. B. 10 to 15 percent by weight HCI can, the ore that has previously been crushed to a grain size below 25 mm, added. The temperature is maintained at approximately 90 ° C, in part due to the Heat of reaction and - if necessary - by heating the solution with the help of steam heaters or snakes. After a certain time, e.g. B. one Hour, the iron oxide has completely gone into solution, during practically the whole of it Silica and a portion of clay remain as an insoluble residue, the - if desired - can be filtered off at this stage. Carbon dioxide and some sulphide sulfur escapes in the form of gas.

The resulting solution can e.g. B. 19 / o free hydrochloric acid and have a pH value below 1. All the hydroxides and phosphates remain soluble in a solution with a pH below about 1.5. To knock them down the acidity must be reduced. It is desirable to bring the solution to pH regulate at which essentially the total amount of aluminum and phosphorus is deposited while essentially all of the ferrous iron is in solution remains; this value can easily be determined by experiment; in general this value is between pH 3 and 5.

When the amount of phosphorus in solution is less than its chemical Equivalent of ferrous iron and aluminum, these ions are in the form of the corresponding Hydroxides precipitated.

Decreasing the acidity of a solution formed from an ore in which the iron is mainly in the distant form, can be in various Way. For example, the solution can be treated with enough metallic iron not only to reduce ferric chloride to ferrous chloride first, but also to then react with free acid. But this is relatively expensive, because metallic iron is needed to reduce the total acidity to effect. The acidity is preferably reduced in two stages, with in one stage calcium carbonate, which is added in the form of chalk or limestone is used to adjust the pH to e.g. B. 1.5, while in a second stage metallic Iron is added to reduce the ferric chloride to ferric form and thereafter to react with the remaining free acid until the desired pH, e.g. B. 4 is obtained.

Another way to reduce the acidity of the solution is to use it in that iron ore containing FeO or ferrocarbonate is added to the ferric solution is until z. B. a pH of 1.5 is reached and then metallic iron, such as already mentioned above, is added.

Again, after the addition of calcium carbonate or ferrocarbonate containing iron ore to reach a pH of around 1.5, only so much metallic Iron are added so that it is sufficient to reduce the ferric chloride to ferrous chloride, and a little more chalk or iron ore containing ferrocarbonate are added, to increase the pH to 3 to 5.

Any vanadium present in the ore becomes vanadate at the same time precipitated with the phosphates with a reduction in acidity in the manner described above. The vanadium can be obtained from this precipitate in the form of vanadyl chloride.

After reducing the acidity, the solution is removed from the precipitates separated by filtration. Silica and some clay can also be used at this stage removed if not immediately after the initial acid treatment have been filtered off.

Calcium is usually present in the ore and also in solution as calcium chloride. Preferably most or all of the calcium chloride is precipitated as calcium sulfate, the solubility of which in water is very low. The best way to do this is by adding ferrous sulfate to the solution to give the following reaction: Fe S O4 -I- CaCl "-> Fe C12 -I- Sa S 04 The ferrochloride additionally formed is added to the ferrochloride already in solution. The calcium sulfate is precipitated and removed on filtration.

Alternatively, manganese sulfate can be added to the solution in order to Calcium chloride to react and yield manganese chloride and calcium sulfate.

This addition of soluble sulfate and the precipitation and removal of calcium sulfate are preferably carried out after the reduction in acidity and the Precipitation of aluminum and phosphorus and prior to removal of the precipitated Hydroxides and phosphates.

But it is also possible to use the soluble before reducing the acidity Add sulfate and remove the resulting calcium sulfate.

After filtering to separate the precipitates, the filtered one contains Solution essentially ferrous chloride along with other metal chlorides, mainly with manganese and magnesium chlorides.

To convert the ferrous chloride in the filtered solution into iron oxide, it is first removed from the solution as crystalline ferrochloride and then hydrolyzed. It can be crystallized from the hot solution as FeC12 "2H20, when excess water is evaporated, e.g. B. by submerged combustion heaters; but preferably for this purpose gaseous hydrogen chloride is added to the hot solution of Chlorides introduced. This method has the advantage of a considerable saving in fuel.

The solid ferrous chloride is separated from the mother liquor and can dried and then in water vapor or combustion gases at a temperature of 300 to 350 ° C are hydrolyzed. The hydrolysis to ferrous oxide in water vapor alone occurs very slowly at these temperatures. It's easier and faster if the hydrolysis is carried out in combustion gases that are water vapor and free Contain oxygen, which leads to the formation of ferric oxide according to the following equation 2FeC12 + 21120 -! - O = Fee 03 -i- 4HC1 leads. The one formed as a result of this hydrolysis Gaseous hydrogen chloride can be used again to make freshly arriving iron ore to treat; but it can also be introduced into the hot solution of chlorides, as has already been described above.

Under the preferred conditions the hydrolysis will be the greatest Part of the manganese chloride, any Magnesium chloride and anything Calcium chloride that has not been converted to sulphate and precipitated, not hydrolyzed and can be removed from the iron oxide by leaching in water will. These leached chlorides can be found on the surface of the siliceous Residues of the filtration described above are hydrolyzed. The one with this one Gaseous hydrogen chloride formed by hydrolysis can be recovered and used for treatment of freshly arriving ore can be used.

Although calcium chloride hydrolyzes in the manner described above it is easier and cheaper to separate caleium than calcium sulphate, than to hydrolyze it later as Caleium Chloride. Even the iron in the ferrous sulphate, which is a waste product in many industries, can be obtained as pure iron oxide will. In addition, with the removal of the calcium as sulfate, the solubility becomes of ferrochloride increased.

Example A low-grade ore with the following composition was treated: component ° l0 Total Fe. . . . . . . . . . . . . . . . . . . . . . . 24.1 Fe. 0., ........................... - 23.6 Fe0 ............................. 9.8 A1209 ............................ 4.7 CaO ............................. 23.0 Si 02 1 * 1 * »'''' * 1 * ................. 7.6 Mg0 ............................. 1.6 MnO ............................. 1.7 P2 05 ............................. 0.80 S. ... ..... ................. 0.38 Loss at 900 ° C. . . . . . . . . . . . . . . . . 25.1 The ore was treated with 12bloiger HCi at a temperature of 95 ° C until the acidity dropped to approximately pH 1. The solution was then reduced to ferroform with sponge iron, the amount of which was approximately 10 percent by weight of the ore; the pH value rose to approximately 2.5. Ferrocarbonate ore was then added in an amount approximately equal to 15 percent by weight of the ore treated; the pH rose to approximately 4 and the phosphates precipitated. These were filtered off together with the silica.

The solution contained approximately 10 percent by weight calcium chloride. The stoichiometric amount of ferrous sulfate required by the calcium was then added to the filtrates and the calcium sulfate was filtered off. The resulting solution was then treated with gaseous hydrogen chloride such that gaseous hydrogen chloride was blown into the solution for approximately 30 minutes, with the result that ferrous chloride was precipitated in a crystalline form. The crystals of Fe C12'2 Hz O were filtered off, dried and hydrolyzed in steam and air at 350 ° C, whereby a ferric oxide was obtained with the following composition: Component % Fe209 ............................ 97.3 A12 09 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.03 CaO ............................. 0.60 P2 05 ............................. 0.03 Si O @ ............................. 0.22 MgÖ ............................. 0.15 Mn 0 ............................. 0.37 S ............ ................... 0.034 Loss at 900 ° C. . . . . . . . . . . . . . . . . 1.04

Claims (7)

CLAIMS: 1. A method for treating iron ore, wherein the ore is converted into a solution of ferric chloride, which is also in solution either aluminum or phosphorus, or both contains and the iron is recovered from the solution, characterized in that the iron in a Solution is converted from ferrous chloride, the acidity of the solution is reduced, whereby aluminum or phosphorus or both are precipitated as hydroxide or phosphate, the solution is separated from the insoluble substances and the ferrous chloride present in it is converted into ferrous or ferric oxide. 2. The method according to claim 1, characterized in that that the acidity of the chloride solution is reduced to a pH at which essentially all of the aluminum and all of the phosphorus as hydroxide or Phosphate will be precipitated while essentially all of the ferrous iron remains in solution. 3. The method according to claim 1 or 2 in application to an ore, which contains the iron mainly in the ferriform, characterized in that the ore is first converted into a solution containing ferric chloride and which Reduction to ferrochloride takes place in solution. 4. The method according to claim 3, characterized characterized in that the acidity is reduced in steps, with one step Calcium carbonate or ferrocarbonate can be added to the chloride solution while in In a second stage, metallic iron is added to transform the ferrous iron into ferrous form to reduce. 5. The method according to any one of claims 1 to 4, characterized in that that the ferrous chloride in the solution by introducing gaseous hydrogen chloride is crystallized out. 6. The method according to any one of claims 1 to 4, characterized characterized in that solid ferrous chloride obtained from the solution by hydrolysis in combustion gases containing water vapor and free oxygen, in ferric oxide is converted. 7. The method according to any one of claims 1 to 6, characterized in that that calcium is removed from the chloride solution by precipitation as calcium sulfate will. B. The method according to claim 7, characterized in that the deposition of calcium sulfate is brought about by the addition of ferrous sulfate.