DE2416407A1 - PROCESS FOR THE RECOVERY OF METAL OXIDES FROM ALITIC, SIALITIC STONES OR. MINERALS AND / OR BY-PRODUCTS OF THE INDUSTRY - Google Patents

Description

2416-07

1. CHEMOCOMPLEX VEGYIPARI GEPES BERENDEZES EXPORT-IMPORT VALLALAT, BUDAPEST / TOTGARN

2. TATABANYAI SZENBANYAK, TATABANYA / HUNGARY

Process for the extraction of metal oxides from alitic, sialitic rocks or minerals and / or by-products of industry

The invention relates to a method for the extraction of metal oxides from minerals, rocks and / or industrial By-products ^ the aluminum oxide or aluminum hydroxide contain, in which the starting raw material with ! Calcium oxide and water added, kneaded and then

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is kept under hydrothermal conditions.

The processing of ores or rocks, which besides aluminum oxide also contain other metal oxides, is also common Also containing silica and water of hydration is an exceedingly difficult task, their various modifications different crystal structures cannot be digested with the same ease. As known, the hydrargillite can be easily extracted from bauxites, but from minerals of the diaspore or boehmite structure but can only be brought into solution with difficulty. The best known method of processing minerals and rocks, which usually contain aluminum oxide together with water of hydration, constitutes the digestion of the raw material with caustic soda, the so-called Bayer process. A fundamental factor in the economy of this The process carried out on an industrial scale is the consumption of caustic soda; this parameter is also limited also the processability of such ores.

If the silica content of the ore increases, the modulus, i.e. the ratio, decreases excessively from AIpO., to the SiOp share. It will then become the Digesting increasingly larger amounts of caustic soda, increasingly higher pressures and higher temperatures necessary. The amount of digestion residue, des so-called red mud, increases, and the environment becomes due to the content of dissolving lye in the stockpile material contaminated.

Bauxite with a high silica content, i.e. with a lower one

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Module, you can therefore use the Bayer method above not processed. Such bauxites are therefore subjected to sintering with soda and lime, the so-called "pyrogenic process". This unlocking of the raw material is much less economical than the Bayer process, which is why it is nowhere near in is widespread to the same extent, although - as is known - it was realized on an industrial scale.

In the specialist literature, the treatment with lime, the so-called causticization process, is described for the recovery of the NaOH content from the red mud. Some patents, for example HU-PSs 146 434 and 154 125 and JA-PS 35-4867, also relate to the treatment of red mud with lime to recover the NaOH. Although these methods of treating red mace with lime prescribe a relatively large amount of CaO ($ 33), they were not widely used because they are not economical. This is because a maximum of 50-70% of the NaOH contained in the red mud can be obtained and even this only in a very low concentration, for example 5-24 g / liter. Another disadvantage is that the AIpO cannot be recovered, or only partially, which makes the smelting of the red mud residue uneconomical.

DT-AS 1 280 229 also describes a method for Pretreatment of bauxite or other raw materials suitable for the production of aluminum hydroxide with a alkaline reacting compound, such as calcium oxide,

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been described in the presence of water, wherein for pretreating a zähplastisches mixture of the ground raw material, the alkaline compound and water at temperatures between 80 - 150 ⁰ C is kneaded under application of shear forces intimately, and then optionally stored under hydrothermal conditions. These relatively harsh reaction conditions sometimes lead to the undesired formation of soluble alkali metal silicates. Among other things, this results in increased consumption of caustic soda in the subsequent process steps and thus increased costs. Further treatment of the product produced by the known pretreatment process with soda is also not possible.

Finally, in DT-OS 2 315 8I6 a Process for reducing the sodium content of the accumulated in the Bayer process, filtered off and extracted red mud by causticizing with ! Calcium oxide suggested. In this procedure the red lamb mixed with CaO is subjected to a heat treatment under the action of shear and pressure forces.

According to the invention, it has now been found that the metal oxide content of those stones, or minerals and / or their industrial by-products, which contain aluminum oxide, hydroxide and possibly a large amount of silica, are digested much more easily and economically with lime in a hydrothermal way can. The hydrothermal decomposition means that the starting material - on the molar Al ₂ O, -

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Content calculated - with 1 to 3 moles of lime and - the molar Silicic acid content in the given case additionally with 1 mol of lime and with water in plastic State homogenized and formed, depending on the case at hand, this process is also repeated and thereby the Possibility of hydraulic solidification of this mixture is secured. In these chemical reactions, i.e. with the formation of calcium aluminate and calcium silicate hydrates - there is a disintegration of the crystal structures; they therefore require, depending from the original mineral composition, for a longer period of time. So you have to mix it up stand for a corresponding time at normal temperature leave - similar to concrete - or you have to react by adding heat and increasing the pressure accelerate.

Based on this knowledge, which is the essence of the invention, the hydrothermal exploration in several Stages carried out. First, by homogenizing the surface to be processed, constantly forming new surfaces Feed material brought into intimate contact with lime or hydrated lime. The chemical reagent, namely CaO, is applied together with water and enough time is allowed to loosen the existing structure and new connections can arise.

The great importance of hydrothermal expansion according to the invention is that this difficult task with the choice of favorable conditions very little energy expenditure due to lengthening

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the time factor or by heat treatment a temperature of 6θ ~ 1ΟΟ C or in some cases 10-180 ° C dissolved x »iird. In branches of industry, however, that to work with large volumes and storage spaces this task is nothing new. As is known, the stocks of raw material are particularly red mud the alumina industry for several months or several years.

Another advantage of the method according to the invention lies in the easy industrial usability of the by-product after the hydrothermal Breakdown and subsequent release of the individual metallic components is obtained "

Furthermore, the method according to the invention has the advantage that after the hydrothermal digestion, the individual metallic components can be released with acid or alkali, or with water to obtain the Na ^ O from the red mud , depending on the desired goal.

It is also an advantage of the process that any by-product containing alumina, e.g. Red mud or pulverized coal slag (fly ash) from power plants etc. can be processed. Potash salt can also be made from rocks (minerals) that contain KpO, be won; In this way, excellent quality fuller's earth can even be made from bentonites produced in a cold way much more economically than before will.

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After or during the hydrothermal dissolution the invention is the starting material with a corresponding amount of lime - in the form of CaO or Ca (OH) ρ and homogenized to the required extent with water and then optionally shaped or granulated. In The silica-excluding quartz and aluminum oxide components react in the system obtained in this way the silicate rock (minerals) of mostly crystalline structure with the lime and water already contribute normal temperature chemically by hydrothermal means and calcium aluminate or calcium silicate hydrates are formed, similar to the hydrates of cement minerals, while the system solidifies hydraulically. The speed of the chemical reactions can be increased by increasing the temperature, i.e. by the same steam treatment as with concrete hardening, strongly accelerated atmospherically or under pressure and thus the required Response time can be shortened to a few hours. Namely, at ordinary temperature, due to the reaction rate the reaction time depending on the mineral and chemical composition of the starting material and thus the formation of the desired structure of the end product, a few days, possibly even a few weeks, require.

After or during the hydrothermal digestion, calcium aluminate and calcium silicate hydrate systems are formed. These therefore also contain water of hydration and from them Al ₂ O ^ can primarily be washed out with soda (Na ^ CO ^) or with diluted mineral acids, while in red mud the Na ₂ O with water, the Al ₂ O ^ ₅ with

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Soda solution or dilute mineral acids in a cold state free of silica and iron, can be dissolved and washed out. Through a similar preparation, the K _? O, from the bentonites, however, the metal oxides in the amount necessary for the production of fuller's earth can be dissolved in a cold state with mineral acids within a short time. If the silica content is higher, the residue can be solidified hydrothermally for further processing by adding more lime. Incidentally, when dissolving with both acid and alkali, the residue can be filtered easily and sedimented quickly.

The main stages of the method according to the invention are the following:

- Determination of the necessary amount of lime in the way, depending on the way of release (soda solution or Acid solution) that according to the ΑΙρΟ -, - content calculated per 1 mole of 1-3 moles of CaO, and optionally 1 mole of CaO for every 1 mole of silica content is admitted

- homogenization of the raw material with water and the calculated amount of lime,

- granulation of the homogenized substance or suitable shaping,

- Maturation of the homogenized substance by storage at ordinary temperature, or at one up to

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IQQ ⁰ C increased temperature and atmospheric pressure or in a closed system with a vapor pressure exceeding atmospheric pressure at a temperature not higher ^{than 200 0 C,}

- Comminution of the hydraulically solidified system

to a size of jK) GO-6Q / U

- leaching or solution,

- filtration,

- processing of the mother liquor into metal compounds,

- Processing of the feed kuefeens. "

Jm generally used at det method according to the invention comprises as a guideline: Is the starting material - ait exception of bentonite - a tandem (! Kaolin t, hat) or Feldspatart, so must generally to a hydrothermal treatment of a few hours at 100-2QO ⁰ C be applied. If an acid is used for the dissolution, the duration of the heat treatment is shorter and the amount of lime required for hydrothermal decomposition is less than if the alufitiniuffihydroxides were dissolved and washed out with soda. In the case of Ro tsehlamu, bentonites and bauxites of the hydrargillite, Böh-EdLt, Biaspor type »hydrothermal decomposition with lime can take place through a Bauer reaction of a few days or weeks at normal temperature, whereby the pressed shaped stones or granules 5- Can be stored in the storage area for 6 days or 2-4 weeks at normal temperature; however, these can also be stored with steam for ^ -5 hours after their production

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a temperature of 80-110 ° C at atmospheric pressure, similar to the maturation process in the manufacture of concrete building elements. In certain cases However, it is more casual only with several Böhrait and To carry out the heat treatment for a few hours at a higher temperature, e.g. with a vapor pressure of 5-5 atm.

The substance prepared with hydrothermal expansion has considerable strength (20-100 kp / cfs} in the form of pellets as well as granules even at normal temperature after a day. When dissolved with soda, the solidified pellets or granules are sweet Grind to an Eorn size below IQQßi and then boil in the soda solution for 1-3 hours. Bern System has to add enough soda that the resulting HaOH is sufficient to dissolve, ie all Kaleiura aluminate is quantitatively broken down In the case of diaspore or tonsil minerals as the starting material, the treatment of the forest stones must be carried out with heat or in an autoclave at a higher temperature, twice at 150-180 ° G, for at least 5-5 hours. In this case - as already mentioned - a Larger amount of alkali, 2-5 hols of lime (CaO or Ca (OH) ^), are used than is required for lasering with acid that is.

When determining the required amount of lime, it is considered to be general rule that with acidic dissolving for the whole

of the starting material the amount of CaO between

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Mono- und'Dikalciuraaluminat is expected. Therefore, it must, for example at a bauxite with 50 wt # AIgO-, - be between 28 wt% and 56.5 wt% of CaO added - calculated on bauxite weight....

A very important precondition of the method according to the invention is the homogenization to the necessary extent. This means a high degree of mixing of the system consisting of the starting material, the determined amount of lime and water, in such a way that, if possible, no lumps of a size exceeding 100 Ai may occur in the homogenized mixture, neither of free lime nor of free starting material. The lime should completely cover the secondary particles of the starting material. In general, only the kneading and mixing devices used in the coarse and fine ceramics industry for the treatment of clayey-colloidal systems are the most appropriate devices. This also includes, for example, the brick press and other similar kneading mixers, which can be combined for sufficient homogenization, or used for the production of pellets and granulates in such a way that two presses are installed one behind the other, whereby the head opening of the first press is provided with a strong plate, which has been perforated with holes of the appropriate diameter. The second press is connected directly to this and does the final shaping and granulating. It is of course necessary that the starting material is comminuted or dispersed in water. This process takes place in an upstream agitator, for example in a pan mill, in which the feed material

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mixed thoroughly with the necessary amount of lime and water will. If a corresponding homogenization cannot be guaranteed, only a breakdown can be made to a relatively lesser extent.

In the method according to the invention, it is expedient to choose nitric acid for dissolving by acid treatment. In the process according to the invention, the choice of nitric acid is important because in this way, in addition to the aluminum hydroxide (alumina hydrate) precipitated from the nitric acid solution with ammonia, potassium and ammonium nitrate salts in the equivalent value of the nitric acid used for dissolution are formed; these are the well-known artificial nitrogen fertilizers. As is known, the amount produced from these in the technically highly developed countries by far exceeds the volume of alumina production. The nitric acid used for dissolving is not lost, but is used in its entirety in the form of artificial fertilizer salts, which can be filled into sacks, placed on the market and recycled. The process carried out with hydrothermal lime treatment or nitric acid or soda solution is also very advantageous because the production of alumina requires far less equipment and facilities than the Bayer process. With the method according to the invention, even the capacity of existing plants that work according to the Bayer method can be significantly increased. The cloud density can be increased up to 50 % instead of the usual 15 °. On the other hand, caustic treatments in autoclaves are not required,

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Stirring, diluting, sedimenting and numerous others cumbersome, time-consuming and expensive work processes. Finally, there is also no treatment and Storage of the worrying red mud. As a result, one requires for the procedure built according to the invention at an artificial fertilizer factory, so not according to Bayer's view Technology working alumina factory with the same capacity significantly lower investment costs, as a Bayer'sches work and it is part of it the entire output is used.

The process according to the invention is also useful if not the acid process for obtaining the Aluminum oxide is applied, but after the hydrothermal digestion with lime according to the known Technology that dissolves with soda is applied. This is particularly useful when in the starting material Iron is present in such a form that it partially dissolves in nitric acid. Also therefore recommended hydrothermal decomposition, since instead of the much more expensive NaOH only for dissolving Soda can be used and - as already mentioned a cloudiness of much greater concentration from the digested Starting material is produced, which is also easier to filter and treat than with the Bayer process is. The Al (OH) · ,, e.g. with carbonic acid, can easily be deposited from the aluminate liquor obtained and the resulting soda solution-lye for reuse be fed back into the solution process. In addition, no caustic soda remains in the red mud

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back., or the remaining AlpO_- The content is greatly reduced by dissolving with soda. The unnecessary and costly rotschlatnm is thus easily preventable according to the invention.

According to the method according to the invention, the red mud polluting the production of alumina (1.5 t of red sludge per 1 t of alumina produced) can be processed further after hydrothermal digestion by lime by _{converting the remaining Na 3} O from it in a proportionate way high concentration (e.g. 50-100 g / liter), completely washed out with water.

This process can be combined by addition of sodium hydroxide so that the beigegebane in the equivalent value to exhaust the system amount of soda simply obtained at the boil with water quantitatively ITaOH high concentration "In this way, from the red mud, together with the remaining therein Na ₂ O itself NaOH a concentration of 100-150 g / liter, which partly also contains dissolved aluminum oxide from the red mud. The resulting concentrated lye is separated from the red mud, which has now been freed of sodium, which remained in water when it was dissolved, while the remaining aluminum oxide can already be dissolved in the cold state with dilute nitric acid. The residue from this dissolution process can be smelted without any further treatment or, if necessary, after lime briquetting. However, you can also proceed in such a way that you can use the soda produced

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highly concentrated lye brings the aluminum oxide remaining in the red mud into solution as sodium aluminate in the usual and known manner, as has already been mentioned earlier. The solution residue that remains after each of the dissolving processes, which mainly contains Fe ₂ O- *, less TiOg and silica, or larger quantities of CaCCW when dissolving with soda, can be compacted ^{with a few percent burnt or slaked lime with the formation of calcium silicate / aSrcn 1} solidified in a hydraulic way and in this form is easily suitable for smelting. In the process according to the invention, the lime in the ratio of tripicalcium aluminate formation from AlpO is generally used to obtain the NapO content from red mud, instead of the previously mentioned monocalcium aluminate in the hydrothermal process.

As mentioned earlier, after the hydrothermal decomposition with lime, some of them become potassium oxide Rich rocks and minerals are so exposed that the potassium oxide is easily dissolved in nitric acid can be washed out. This is usually done along with the alumina. The amount of hydrothermal Digestion required lime, as well as the type and manner of hydrothermal treatment must depend on the The nature of the raw material. This process is decisive for both metal oxides the crystalline or glass-like structure of the starting material. For example, the potash feldspars, Kalitrachyte with an amount of lime calculated on dialuminate

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be digested, after 6-8 hours of treatment in an autoclave at 8 atm. _{The KpO becomes soluble together with the AIpC 7} even at room temperature or by boiling in nitric acid. In the case of tuff-like rocks with an amorphous structure containing vitreous potassium oxide, a smaller amount of calcium oxide is usually sufficient for hydrothermal decomposition in the manner discussed earlier than in the case of dipicalcium aluminate; the digestion itself then takes place as a continuous reaction or steam treatment at atmospheric pressure for 8 hours.

It was found that the montmorillonite component the bentonite is not always in an optimal ratio for the production of fuller's earth. The crystal lattice of the montmorillonite can namely - as is known in the appropriate state by water compared to the generally shrunk state of the grid are greatly expanded or pulled. The Montmorillonitgttter can expand or contract like a harmonica. When naturally occurring is the crystal lattice of the so-called mountain-moist bentonites in their shriveled, at most in a moderately expanded state. During the acid treatment and boiling, the grid remains in its original state, i.e. it is not expanded still contracted. It is clear that the montmorillonite lattice is opposite in a completely expanded state the middle or shrunken state on the one hand has a much larger surface and on the other hand in the extended extended state the mentioned ones

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basic oxides are dissolved faster and to a greater extent with mineral acids under otherwise identical conditions v / can ground.

According to the method according to the invention, the montmorillonite lattice expanded to the maximum before the acid treatment. This gives the montmorillonite a significantly larger surface than in the natural state and the dissolving of the bases mentioned is also essential accelerated; on the other hand, the starting montmorillonite can be converted into a bleaching earth with a much larger, more active one Surface and therefore clearly can be produced with much better clarification efficiency.

This grid expansion can be achieved through an intensive Achieve kneading of the montmorillonite with lime and water.

The rapid solubility of the basic components of the montmorillonite lattice or the strong loosening these components in the lattice itself is according to the invention on a hydrothermal route by forming the Reached calcium polyaluminate hydrates. From those in these Condition brought bentonites and other suitable silicate minerals and rocks, such as from the illites and volcanic tuffs, but primarily of course the bentonites Bleaching earths of excellent quality can be produced, boiling in mineral acids instead of those mentioned 7-10 hours reduced to a time of only 20-60 minutes, or, depending on the starting material, a release

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takes place even at normal temperature for 20-60 minutes.

Of course, this economic efficiency of the process can be increased by being advantageous Instead of the usual sulfuric acid or hydrochloric acid, an acid that forms artificial fertilizers, e.g. nitric acid, is used for loosening.

Some embodiments of the method are described according to the invention based _T he cited in the following examples.

example 1

Processing of the bauxite

The starting material is a bauxite with the following mineralogical and chemical composition: mineral composition: 50.14 % hydrargillite (gibbsite), 15.64 % boehmite, 10.00 fo kaolinite, 21.09 % hematite, göthite etc., 5.13 % other components . Module of bauxite: 10.75. Oxidic composition: 50.04 fa AIpO ^ (of which $ 3.95 bound to kaolinite), 4.65 % SiO ₂ , 19.0 fa Fe 0 ^, 2.52 % TiO ₂ , 21/09 % H ₂ O ( Loss on ignition), 2.70 % other substances. The bauxite has a soft, clay-like consistency and is easy to disperse.

There is no lime for the Si0 _p and Al _p 0 ^ of the kaolin

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calculated, but only for the bound aluminum oxide ($ 47). 50% of the amounts of lime are calculated as monopalcium aluminate and 50% as dipcalcium aluminate. A total of 150 kg of calcium oxide is weighed out. The corresponding amount of hydrated lime is roughly mixed with water (approx. 25%) in a pan mill with 1000 kg of bauxite, then the resulting mass is sent through a brick press for homogenization, the top opening of which is provided with a perforated (hole 0 25 mm) plate is. The granulate obtained in this way is passed through the second brick press connected in series and shaped into bricks of normal size. This Zie _T gelsteine are stacked in the parking space and stored for one month at ordinary temperature. During this time, the breakdown of the bauxite components takes place. The hydraulically solidified material is then ground to a grain size below 100 / u and kept at the boil for 2 hours at atmospheric pressure with an amount of soda solution (369 g / liter) equivalent to the amount of calcium oxide added, the ratio of bauxite to soda solution being 1: 2 is adhered to. After boiling, the Al (OH) - is obtained in every respect according to the Bayer method. The amount of hydrate obtained is 80 % of the original amount. The residue is suitable for smelting after peUetization.

Example 2

The procedure is the same as in Example 1,

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However, with the difference that after digestion or after one month of storage, the coarsely ground material is dissolved in 10% nitric acid with constant stirring until the solution reaches pH 2. After the solution has been piled up, the alumina hydrate is separated with ammonia, after which the calcium and ammonia nitrate remaining in the solution is processed into artificial fertilizer in a known manner by evaporation. Contains the residue after the solution by acid, the Fe ₂ O ,, TiO ₂ and together with a little silica not decomposed to a great extent kaolinite, is homogenized using 3 wt.% CaO and granulated. The material obtained in this way solidifies in a few days and thus reaches a state suitable for smelting.

Example 3

The starting material exhibits carbonate bauxite Halimba of the following mineralogical and chemical composition:

1. Mineralogical composition: Al ₂ 0 ^ content of kaolinite: 6.2 fo, the Diaspors: 0.5%, of gibbsite: 0.9 of the boehmite: J58%.

2. Chemical composition: ignition losses 15 * 9 % » Al ₂ Oy 45.6 ^, Fe ₂ O ₃ : 20.3 %, SiO ₂ : 8.1 <p, TiO ₃ : 2.0 %, CaO: 3, 9 %, MgO: 2.0 %, modulus: 5.6.

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To 1 t of the roughly pre-crushed bauxite calculated on the wet-free substance, 620 kg of quick lime (CaO) is added in a ratio of 2.5 CaO / AlpO and the mixture is ground in a ball mill to a fineness of less than ^ 00 / rev. The slurry is then moistened with water until it has a slightly plastic consistency in the agitator trough of the brick press and then the mass is driven through the press described in Example 1, which is provided with a perforated plate, so that granules emerge from it. These granules are treated in the autoclave for 3 hours with steam at a pressure of 5 atm. The digested system is ground to a grain size of less than 100 / rev and the ground material, which contains 70 kg of soda, is kept boiling in 4 nr V / water for 2 hours at 110 ° C. The solution contains 90 % of the original ΑΙρΟ -, - content, which can be deposited as a hydrate by adding carbonic acid in a known manner. The soda content of the solution remaining after filtration is 292 g / l Na ₂ CO- and is returned to the cycle.

Example 4

The starting material is red mud from Almasfüzito with the following chemical composition: ignition losses: 9.50 %, SiO ₂ : 13.20, Al ₂ O- ,: 18.04 fo, Fe ₃ O ₇ : 39.60 %, CaO: 1.33 %, TiO ₂ : 4.37 % 3 Na ₂ O: 9.70 #, Na ₂ CO ,: 2.18 % _t other: 2.08 fo.

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Calculated from this, the total NaOH content of the red mud is 14.4O % per t. The starting sludge with the above chemical composition has a moisture content of 36% _t es v / earth - based on 1000 kg dry matter, 150 kg raw material is weighed. This amount contains Ij52 kg of bound silica, I80 kg of AlpO ,, and 144 kg of NaOH. If the CaO required for hydrothermal decomposition is _{calculated as tricalcium aluminate for Al 2} O ^, but as monocalcium silicate for SiOp, then 297 + 123 = 420 kg CaO must be added to 15.68 kg of red lamb. The CaO consumption is $ 90. Of this, 462 kg are added in the ground state, supplemented with 210 liters of water. The red mud is premixed and pre-homogenized with the calculated CaO and water in a pan mill, type Eirich. The further fine homogenization and shaping is carried out according to Example '1 for bauxite; then the pellets of normal brick size are stacked outdoors under a protective roof for 5 days. During this time, the compacts are hydraulically solidified. The weight distribution of the mixture is: 15.6 kg red mud with natural moisture, 462 kg CaO, 210 kg water, a total of 2232 kg. A water loss of approx. 10 fo occurs during storage, so that the weight of the mixture is 2000 kg, in which 144 kg NaOH content means 7.2 %, but 180 kg means 9 % .

The hydrothermally exposed and solidified with lime Red mud is then ground to a fineness below 100 / rev and with 180 liters of water for 1 hour

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kept boiling at atmospheric pressure. Thereafter, the easily filterable slurry is filtered in a vacuum filter, 'to give a liquor in the filtrate, the 1 in I900 water I4o kg NaOH, that is 73.6 g / liter of NaOH, in addition to a content of 50 $> Al (OH) -, contains. This liquor is returned to the Bayer facility for further use. The remaining proportion of Al (OHK is obtained according to the process given for the processing of the bauxite Example 2 after the acid technology from the left on the filter press fabric After dissolution by acid \ CLRD the residue thereby obtained -. The most part of Fe ₂ O., , SiOp and TiOp - kneaded and shaped with an amount of CaO calculated on the SiOp content as monocalcium silicate, so that the pellets solidify and can be transported or smelted after just 1 day of storage.

Example 5

Otherwise, the procedure is exactly as in Example 4, with the difference that this is done by time reaction with lime digested and solidified, but then ground material is dispersed in a ratio of 1: 1 in water, but the released NaOH is dissolved and washed out. After that 4 m water and enough soda are added to 2 t of the material that the soda breaks down half the amount of the lime bound to AIpO-. So it becomes one of 150 kg of CaO equivalent amount, i.e. 289 kg of soda, introduced into the system, which then results in 214 kg of NaOH. Accordingly, are located

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- together with the 144 kg NaOH of the red mud, 358 kg NaOH in the system and this includes 90 kg AIpO ^. In this way, 50 % AIpO can be dissolved and extracted from the red mud without major sodium (soda) losses.

Example β

The procedure is as in Example 4, with the difference that after leaching the digested red mud with water, ie after dissolving the NaOH, the filtration takes place and then the CaO and AlpO _v components are extracted from the lye-free residue obtained with salpe -yric acid can be dissolved and washed out in the same way as described in the example for the acidic processing of bauxite.

Example 7

The starting material is plug ash from the dump in Tatabanya (Banhida) with the following chemical composition: Si0 _p : 43.82 fo, Al ₃ O ₃ : 30.04 yes, Fe ₂ O ^: 7.60 #, CaO: 5.52 %] MgO: 0.32 fj, Na ₂ O: 1.24 ? ,, K ₂ O: 1.24 %, SO ₃ : 1.37 $, ignition losses: 9.24 #.

The CaO required for the hydrothermal decomposition of the AlpO- is calculated taking into account the 5/52 % CaO content on dipicalcium aluminate. Accordingly

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JOO kg of GaO or the equivalent amount of Ca (OH) _{2 are added} to 1 t of dry fly ash. With this amount of lime, the fly ash is homogenized as in Example 1 and molded and then the bricks are Fort 6 hours Tnit at a temperature of 8o to IGO ⁰ C Dampfbeliandelt. The solidified pellets are ground to a grain size of less than 1 mm, and the ground material is dissolved in nitric acid for 1 hour or with an excess of acid that results in a maximum of pH 2. The nitric acid has a concentration of 10 fa . After filtering the Al (OH) ₇ becomes. excreted in the familiar tit with ammonia, and the salts that remain in the solution and consist of mitrates are used to make artificial fertilizers. The recoverable iron-free AIpO ^ is 95% of the Älpö-y-Gefialtes of the coal saplings. The residue can be used as a filter material for wastewater treatment with good adsorption capacity or mixed with 20 f * CaO to form building blocks as lightweight concrete, according to the patent application Mr. 2251 / SE / 156 ^ / 197! Budapest, are used.

Example 8

The starting material is a ton of Kalitraehvt regrind from Kanvahegy vorai Telfcibanya, a place with a grain size below IQQ / U and the following composition: SiO ~: 60.93 $ * S, Fe _? 0 ₇ : 3.24 ^, CaO: 4.00 fS, KpO: IQ, 60 ^ _x

_f other: 6.15 / ί.

With the 3 mol CaQ calculated on the ÄlpO ^ content, i.e. with 250 kg of lime and the required amount of water

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Homogenized in the brick press and added to the task Form stones are pressed, which are then in the autoclave for 6 hours treated with 8 atm pressure. When the solidified semi-finished product is crushed, it will dissolve in Nitric acid carried out as in the previous examples, after which the filtrate in addition to Ca and Al, Fe and Ha nitrate contains the potassium salt as potassium nitrate. These substances are sold together as mixed fertilizer salt brought. Bas mixed artificial salt can be mixed with the on Silica components remaining on the filter as a carrier can be mixed, but the alurainium hydrate can also be used - drove out already mentioned in the earlier examples the original filtrate with the ammonia can be recovered in a known manner, especially if the impurities due to iron are only slight.

Example 9

The starting material is potash bentonite from Istenmezeje (Hungary), with an exnem potash montmorillonite content of 80%, that of Al "a,: 18%, Fe ₀ O,: 4, 0 $ and MgO: 3.0 fa plus 63 , 0 % SiO ₀ .

The required for the formation of Äluminiuranitrat GAO ECenge is 10 wt £, that is, to 1 mole of AIP ⁰ -. * Not 1 mole gaq. The pre-dried bentonite is crushed in a toothed roller grinder to a grain size below 5 Em, placed in a brickworks pan mill, 10 fa GaO or an equivalent amount of hydrated lime is added, the mass is brought to the necessary moisture, then pushed through in the pan mill,

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then moistened in the trough mixer, depending on requirements, and finally placed in a brick press with a perforated lip plate for further homogenization or granulation. The semi-finished product obtained in this way is stored outdoors for 10 days at natural temperature, then ground to a grain size of a few tenths of a millimeter, mixed with water to form a dense, pumpable work slurry and pumped into a suitable vessel, where it follows to 60-70 Dissolving the basic components (AlpO ^, FeO ₇ , MgO) of the bentonite is mixed with nitric acid in such a way that the amount of remaining nitric acid advantageously reaches the concentration of normal nitric acid. The boiling is continued for half an hour, after which the working pulp is filtered to a nearly acid-free state and a pH of 4-5, washed out and dried. Further grinding is usually not necessary as the end product is in a slightly dusty, disintegrated state. The filtrate, which contains all released substances in the form of nitrates as well as a small excess of nitric acid, is neutralized with ammonia and, after the water has been removed, can be processed into artificial fertilizer by evaporation. In order to increase the concentration of synthetic fertilizer salts in the filtrate, this salt solution can be used instead of pure water to mix additional amounts of bentonite with nitric acid.

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Claims (10)

Claims 1. A process for the extraction of metal oxides from minerals, rocks and / or industrial by-products containing aluminum oxide or aluminum hydroxide, wherein the starting material is mixed with calcium oxide and water, kneaded and then kept under hydrothermal conditions, characterized in that the starting raw material, which is expedient has a grain size of 6o-500 / U, for every 1 mole of its aluminum oxide content with 1-J5 mole of CaO, and additionally for every 1 mole of its silica content with 1 mole of CaO, or with the amount of Ca (OH) equivalent to this _p and water are kneaded, homogenized and shaped into a plastic mass at room temperature and atmospheric pressure, if necessary the kneading and shaping repeated, then- = but the product is allowed to mature at normal temperature and normal pressure, or at a temperature not higher than 2oo C and the associated pressure until the end of the hydrothermal decomposition process and the hydrau After setting, the solidified product is granulated, the hydrothermally digested components are dissolved from the granulated material, the solution is separated from the residue and then processed in a manner known per se. 2. The method according to claim 1, characterized in that the on hydrothermal Paths open and hydraulically solidified material - 29 - 5098Λ2 / 0855 before the dissolving process at least to the size of a pea or a even smaller grain size is granulated. 3 · Process according to claims 1 to 2 for processing bauxite, characterized in that according to the Al ₀ (X content of the bauxite for every 1 mole of AlpO-, 1 mole, at most 2 moles of CaO, and thus the digestion is carried out, the digested , granulated material but with dilute mineral acid, expediently with 5 to 2o ^ -iger nitric acid, is dissolved. 4. The method according to claim 1 and 2, for processing bauxite, characterized in that according to the Al _o 0 _v -C-e content of the bauxite for every 1 mole of AIpO-, 2 moles, at most 3 moles of CaO, and thus the ¹ hydrothermal Digestion carried out, but the digested granulated material is dissolved with a soda solution. 5. Method according to claims 1 and 2 for processing the red mud, characterized in that that according to the AlpO ^ content of the red mud for one mole of AIpO- each. at least 3 moles of CaO, the silica content however, for every 1 mole of SiOp, 1 mole of CaO is calculated, with these surcharges on hydrothermal basis Ways the digestion is carried out, the digested granulated material with water and / or then soda solution, or with water and dilute mineral acid, expediently with 5 to 20 $ -iger nitric acid, is dissolved. 509842/0855 6. The method according to claim J> and 5. · characterized in that the alumina hydrate is separated from the acidic mother liquor by adding ammonia and the remaining solution is used for the production of artificial fertilizers. 7 · Process according to claim 4 and 5 j characterized in that the aqueous and / or soda mother liquor is processed according to the Bayer process, if necessary by hydrate separation with carbonic acid. 8. The method according to claim 1 and 2 for the recovery of potassium oxide from the mineral raw materials containing such, characterized in that for 1 mole of Al ₀ O ,. 3 mol CaO are calculated and the digestion is carried out by hydrothermal means and then the digested, granulated material is dissolved with dilute mineral acid, expediently with lo-30% nitric acid. 9. The method according to claim 1 and 2, for the production of fuller's earth, characterized in that that for every 1 mole of AIpC ^ 1 mole of CaO is calculated and thus the hydrothermal exploration carried out and the exposed, granulated material with dilute mineral acid, expediently with lo- ^ o ^ -iger nitric acid, is resolved. 10. The method according to claim 1 to 9, characterized in that the mixture of starting material and CaO or Ca (OH) _{p is} homogenized and shaped in a brick press. ι
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