WO2024028151A1

WO2024028151A1 - Method for processing potash ores

Info

Publication number: WO2024028151A1
Application number: PCT/EP2023/070497
Authority: WO
Inventors: Jochen BROD; Uwe Wachsmuth; Ludger Waldmann
Original assignee: K + S Aktiengesellschaft
Priority date: 2022-08-02
Filing date: 2023-07-25
Publication date: 2024-02-08
Also published as: DE102022119322A1

Abstract

The present invention relates to a method for processing potash ores, comprising the following steps: - underground mining of potash ores (S1) by way of cutting and/or by way of boring and shot-firing, - grinding and/or sieving the obtained potash ores (S1) by means of a grinding and/or sieving device (16), and - sorting , with the aid of sensors, the ground and/or sieved potash ores (S2) into an intermediate fraction (S7) and a second oversize product (S9) by means of a sensor-aided sorting device (30).

Description

Process for preparing crude potassium salts

The present invention relates to a method for preparing raw potash salts.

It is known to produce a marketable potash product from raw potash salts from potash deposits using wet processing processes such as flotation and hot dissolving processes with subsequent crystallization and/or an evaporation process. A marketable potash product is defined below as a product containing potassium chloride or potassium chloride and magnesium sulphate with a sodium chloride content <30 wt. -%, preferably <15 wt. -% and in the best case <5 wt. -% can be understood.

Due to the fact that at least one drying step is necessary in the wet processing processes of the raw potash salts, the energy requirement of such processing processes is correspondingly high.

The raw potash salts are usually processed in above-ground facilities. The disadvantages here, however, are in particular the space required for the corresponding systems, the above-ground storage, the resulting change in the landscape and the need to dimension the required shafts sufficiently large. The financial outlay for carrying out the wet processing processes is correspondingly high.

For the relevant state of the art, please refer to DE 10 2017 125 467 Al, DE 11 2013 006 100 T5 and DE 43 43 625 CI. The object of one embodiment of the present invention is to propose a method for processing raw potassium salts, with which it is possible to create a remedy for the above-mentioned disadvantages and in particular to create the possibility of carrying out the method underground .

This task is solved with the features specified in claims 1, 7 and 14. Advantageous embodiments are the subject of the subclaims.

One embodiment of the invention relates to a method for processing raw potash salts, comprising the following steps:

- Underground extraction of raw potash salts by cutting extraction and/or by drilling and blasting,

- Grinding and/or sieving the raw potash salts obtained using a grinding and/or sieving device,

- adding organic and/or inorganic conditioning agents to the ground and/or sieved raw potassium salts using a first addition device,

- electrostatic charging of the conditioned raw potassium salts using a charging device, and

- Separating the electrostatically charged raw potassium salts into a product fraction and a first residue fraction using the electrostatic separating device.

The electrostatic charging of raw potassium salts can be realized, for example, by means of triboelectric charging, for which reference is made to DE 10 2017 218 206 Al. The conditioning agents are used to exchange charges in the ground and/or sieved raw potassium salts, which promotes electrostatic charging. The steps of the method according to the invention according to the previously defined embodiment are exclusively “dry” steps that do not use liquid, in particular water, while the flotation and hot dissolving process steps mentioned at the beginning are liquid-based, especially Water-based, work. The “dry” process according to the invention therefore eliminates the drying process, which requires a lot of energy. As mentioned at the beginning, the processes known from the prior art often also use evaporation and/or crystallization processes, which can be dispensed with in the process according to the invention. The associated energy requirement is eliminated.

Depending on the design of the liquid-based processing process, there is almost always a certain loss of the product fraction due to release, which cannot occur with the dry process.

In this respect, the method according to the invention is more energy efficient compared to the processing methods mentioned at the beginning, so that ecological and economic advantages can be achieved. In particular, according to the invention, the carbon dioxide footprint can be reduced in the production of marketable potash products.

It should be noted that the term “first residue fraction” should not be understood to mean that a second or further residue fraction is necessarily generated.

According to a further embodiment form the step of grinding and/or sieving the obtained

Potassium crude salts underground or

- the steps o of grinding and/or sieving the raw potassium salts obtained and o of adding organic and/or inorganic conditioning agents to the ground and/or sieved raw potassium salts or

- the steps of o grinding and/or sieving the raw potassium salts obtained and o adding organic and/or inorganic conditioning agents to the ground and/or sieved raw potassium salts and o electrostatically charging the conditioned raw potassium salts or

- the steps of o grinding and/or sieving the obtained raw potassium salts and o adding organic and/or inorganic conditioning agents to the ground and/or sieved raw potassium salts and o electrostatically charging the conditioned raw potassium salts and o separating the electrostatically charged raw potassium salts ze carried out during the day.

In contrast to the wet processing processes mentioned at the beginning, all steps of the process according to the invention can be carried out underground with comparatively little effort. However, it is also possible to only carry out certain steps during the day. The term “interday” is often used synonymously with the terms “underground” and “mining”. The surface area consumption and the impact on the landscape are reduced. Typically, the extraction effort decreases the more steps are carried out underground, so that the relevant shaft systems can be made smaller, which benefits the economic efficiency of the process.

According to a further embodiment, the following steps can be carried out between the step of grinding and/or sieving the raw potassium salts obtained and the step of adding organic and/or inorganic conditioning agents:

- sensor-assisted sorting of the ground and/or sieved raw potassium salts into an intermediate fraction and a second residue fraction using a sensor-assisted sorting device,

- Grinding and/or sieving the intermediate fraction using a further grinding and/or sieving device, and

- Adding organic and/or inorganic conditioning agents to the ground and/or sieved intermediate fraction using the first addition device.

Due to the combination of separation using electrostatic charging and sensor-assisted sorting, marketable potash products can be produced from the raw potash salts, usually sylvinite, carnallitite, polyhalitic hard salts or kieseritic hard salts, with a comparatively low energy input. Sensor-assisted sorting can be carried out either underground or above day. The subsequent steps of grinding and/or sieving and adding a conditioning agent serve to prepare the intermediate fraction for electrostatic separation.

In a further developed embodiment, the sorting device can comprise an X-ray transmission sorter and the step of sensor-assisted sorting can be carried out using an X-ray transmission measurement by means of the X-ray transmission sorter.

It has been found that sodium chloride (NaCl), especially in the form of halite, can be easily separated from the raw potassium salt and in particular from sylvinite (potassium chloride, KCl) using an X-ray transmission sorter.

In a further developed embodiment, the sorting device can comprise an optical sensor and the step of sensor-assisted sorting can be carried out using an optical measurement using the optical sensor.

In particular, cameras can be used as optical sensors, which can be equipped, for example, with wavelength-dispersive elements and suitable spectral cameras, and in simple embodiments can also be equipped with optical filters. It has been found that by means of optical sensors, components that are particularly different in color, for example evaluated on the basis of a wavelength-dependent spectrum, can be easily separated from a raw potassium salt, for example clay. For example, clay can be understood as a mixture of muscovite, illite, kaolinite, chlorite and clinochlor. the, whereby other compositions can also be referred to as clay. In most cases, sound is not desired in the product.

In a further embodiment, the sorting device can comprise a near-infrared sensor and the step of sensor-assisted sorting can be carried out using a near-infrared measurement using the near-infrared sensor.

The use of near-infrared sensors (also referred to as NIR sensors) enables in particular the separation of mineral phases that contain hydration water (e.g. kieserite, carnallite) from the potassium raw salt. The selection of the suitable near-infrared sensor and the wavelength that the relevant near-infrared sensor uses are based on the boundary conditions of the respective application and in particular based on the composition of the mineral phases to be separated.

According to another embodiment, you can

- the first residue fraction and/or

- the second residue fraction is introduced into underground cavities.

Due to the introduction into underground cavities, also known as stacking, there is no need for above-ground stockpiling. In addition, the residue fractions do not have to be transported to the surface of the earth (above ground), which is why the relevant mines can be made smaller. In addition, no energy has to be used to transport the residue fractions above ground. A further developed embodiment is characterized by the following step:

- Adding nutrients to the product fraction using a second addition device.

The effectiveness of the fertilizer can be increased by adding nutrients such as biostimulants, micronutrients, sulfur, boron, zinc and/or manganese salts.

In a further embodiment, the following step may be appropriate:

- Compacting and/or granulating the product fraction or the product fraction enriched with nutrients using a compacting device or a granulation device.

Compacting and/or granulating serve to bring the product fraction to the desired grain size distribution or particle size distribution. For example, when using potash products as fertilizers, it is advisable not to fall below a certain grain size in order to, among other things, prevent the applied fertilizer particles from being blown away by the wind. In order to be absorbed into the soil, the fertilizer must dissolve in rainwater. The grain size can be used to control how quickly the fertilizer dissolves. In this respect, a long-lasting and even supply of the soil can be achieved with the appropriate choice of grain size.

In a further developed embodiment, the method can include the following step: - Adding additives and/or organic and/or inorganic conditioning agents to the compacted and/or granulated product fraction by means of a third addition fraction.

The additives can be used to influence the physical properties of the product fraction, such as flowability and storage stability. The dust and caking behavior can be adjusted by means of post-treatment with organic and/or inorganic conditioning agents.

In a further developed embodiment, the following step or steps can be carried out day-to-day:

- the step of adding nutrients to the product fraction or

- the steps of o adding nutrients to the product fraction and o compacting and/or granulating the product fraction or

- the steps of o adding nutrients to the product fraction, o compacting and/or granulating the product fraction and o adding additives and/or organic and/or inorganic conditioning agents.

Since the steps mentioned in this embodiment of the proposed method are usually optional and therefore not the entire product fraction is subjected to these process steps, it makes sense to use some or all of them Steps to be carried out above ground. As a result, for example, the nutrients, the additives and/or the conditioning agents do not have to be transported underground again and after the steps mentioned have been carried out with the appropriately treated product fraction.

An implementation of the invention relates to a method for processing raw potassium salts, comprising the following steps:

- Grinding and/or sieving the raw potassium salts obtained using a grinding and/or sieving device, and

- Sensor-assisted sorting of the ground and/or sieved raw potassium salts into an intermediate fraction and a second residue fraction or a further intermediate fraction using a sensor-assisted sorting device.

It is not absolutely necessary to use the electrostatic separation device to prepare the raw potassium salts.

Depending on the nature of the raw potash salt obtained underground, it may be advisable to carry out one or more sensor-assisted sorting of the ground and/or sieved raw potash salts instead of separating electrostatically charged raw potash salts. The sensor-based sorting devices already mentioned can be used, in particular sorting devices that include an X-ray transmission sorter, an optical sensor or a near-infrared sensor. In this context, the term “second residue fraction” is to be understood in such a way that a first residue fraction does not necessarily have to be present. The terms “first residue fraction” and “second "Residue fraction" serves for better differentiation and does not imply any special relationship with one another. Sensor-assisted sorting can be carried out either underground or above day.

As mentioned, only one sensor-based sort or multiple sensor-based sorts can be performed. For example, a separation of clay using an optical sensor can be the first sensor-assisted sorting step, for example followed by a separation of mineral phases that contain hydration water, for example kieserite, carnallite, with a near-infrared sensor. As a final step, sorting can be carried out using an X-ray transmission sorter in order to separate sodium chloride (NaCl), particularly in the form of halite, from the raw potassium salt. Other combinations of these sorting steps are also conceivable. Furthermore, reference is made to the above statements on sensor-based sorting. This does not necessarily result in a residue fraction that is not further processed. It is also possible to obtain two intermediate fractions that are further processed separately. In addition to the raw potash salt, the kieserite-containing fraction can also be further processed.

The particle size at which the sorting is carried out depends on the degree of adhesions of the raw potassium salt obtained. The optimal particle size can only be determined with appropriate examinations of the raw potassium salt obtained. It is important to note that the particles of raw potassium salt to be sorted must not be too small. This is due, among other things, to the fact that in sensor-assisted sorting, every single particle must be detected by the sorting device. For this purpose, there must be a monolayer of the particles to be sorted. The finer the raw potassium salt is ground, the more The number of particles per unit volume is also higher. As the number of particles increases, the time required to separate a unit volume of the raw potassium salt also increases, which reduces the throughput and makes the sorting more economical.

For a more closely examined potassium raw salt, sensor-assisted sorting can be carried out economically with a particle size of, for example, greater than 10 mm or greater than 15 mm.

Further training specifies the steps

- grinding and/or sieving the raw potassium salts obtained and

- The sensor-assisted sorting of the ground and/or sieved raw potash salts can be carried out underground.

In particular, the surface area consumption and the associated impact on the landscape are kept to a minimum. Particularly during grinding, dust and noise emissions can occur, which are less disruptive underground.

According to a further training, the method includes the following step:

- Grinding and/or sieving the intermediate fraction by means of a further grinding and/or sieving device to obtain a product fraction or a further intermediate fraction.

As mentioned, sensor-assisted sorting can be carried out economically depending on the degree of adhesions of the raw potassium salt, for example with a particle size of 10 mm or more. In the In general, however, such particle sizes are too coarse for a marketable potash product. Re-grinding and/or sieving the intermediate fraction serves to provide the desired particle size distribution for the potash product.

As also mentioned, several sorting steps can be carried out one after the other. For example, if the clay is separated in a sorting step, the volume of the fraction to be further processed is reduced, so that it may make sense to grind and/or sieve this fraction to be further processed (further intermediate fraction) before the following sensor-assisted sorting step, for example in order to increase the degree of separation to increase.

In principle, the sensor-supported sorting steps can be carried out both underground and above ground. Whether some or all of the sensor-assisted sorting steps are carried out underground or above ground is decided based on the boundary conditions of the respective application.

According to a further development of the procedure, the steps:

- grinding and/or sieving the raw potassium salts obtained (Sl) and the intermediate fraction (S7),

- the sensor-assisted sorting of the ground and/or sieved raw potash salts (S2)

- adding organic and/or inorganic conditioning agents to the ground and/or sieved raw potassium salts (S2) and

- the electrostatic charging of the conditioned raw potassium salts (S3) and

- Separation of the electrostatically charged raw potassium salts is carried out underground. In particular, the surface area consumption and the associated impact on the landscape are kept to a minimum. The noise and dust emissions resulting from the processing of the raw potassium salts obtained are less disruptive underground than above ground.

One embodiment of the invention relates to the use of a sorting device, which comprises an X-ray transmission sorter with an X-ray sensor, for separating sodium chloride (NaCl), in particular in the form of halite, from raw potassium salt and in particular from sylvinite (potassium chloride, KCl). It has been found that sodium chloride (NaCl), especially in the form of halite, can be easily separated from the raw potassium salt and in particular from sylvin (potassium chloride, KCl) using an X-ray transmission sorter.

One embodiment of the invention relates to the use of the product fraction as fertilizer, which is obtained by means of a process according to one of the previously described embodiments.

The technical effects and advantages that can be achieved with the use of the product fraction obtained by means of the process according to the invention correspond to those that have been discussed for the present process. In summary, it should be noted that the fertilizer can be produced more energy-efficiently than the processing methods mentioned at the beginning, so that ecological and economic advantages can be achieved. In particular, the carbon dioxide footprint when producing the fertilizer can be reduced. Exemplary embodiments of the invention are explained in more detail below with reference to the accompanying drawings. Show it

1 shows a basic representation of a first embodiment of the method according to the invention,

Figure 2 shows a basic representation of a second embodiment of the method according to the invention,

3 shows a basic representation of a third embodiment of the method according to the invention,

4 shows a basic representation of the essential steps for carrying out a separation using the electrostatic separation device,

5 shows a basic representation of a first exemplary embodiment of a sorting device,

6 shows a basic representation of a second exemplary embodiment of a sorting device,

Figure 7 shows a basic representation of a third exemplary embodiment of a sorting device.

In Figure 1, a first embodiment of a method according to the invention for processing raw potassium salts is shown based on a basic representation. The processing of raw potash salts is carried out with the aim of providing a marketable potash product in which the sodium chloride content is less than 30% by weight. -% and the share of potassium chloride and, if necessary, the proportion of magnesium sulphate should be increased. The processed raw potassium salt is typically used as fertilizer.

An earth surface 10 is marked in FIG. 1, which divides the representation into an above-ground area 12 and an underground area 14.

In the underground area 14, raw potassium salt z S 1 is obtained in a first step by means of cutting extraction and/or by drilling or blasting. In a second step, the potassium raw salt z S 1 obtained in this way is ground and/or sieved underground using a grinding and/or sieving device 16. The potassium raw salt z S 1 is brought to a grain size distribution in which the subsequent steps, which will be discussed below, can be carried out optimally or almost optimally. Conditioning agents, which can be organic or inorganic and mixtures thereof, are also added to the ground and/or sieved potassium raw salt z S2 during the day by means of a first addition device 18. In the embodiment shown, the addition device 18 interacts with a charging device 19 arranged in the underground area 14, in which the ground and / or sieved raw potassium salt z S2 is charged electrostatically, here triboelectrically. The conditioned and charged raw salt z S3 is then separated into a first residue fraction S4 and a product fraction S5 in a separation device 20 based on the polarity of the particles of the charged raw potassium salt. The first residue fraction S4 is introduced into underground cavities 22, also referred to as offset. The product fraction S5 is conveyed to the above-ground area 12, i.e. to the earth's surface 10, by means of a shaft system 24. The product fraction S5 is used there a second addition device 28 enriched with nutrients, for example with micronutrients and / or biostimulants. It should be noted at this point that this step can also be omitted depending on the desired properties of the potash product. A bypass 27 can be provided accordingly.

Subsequently, the product fraction S5 or the product fraction S5a enriched with nutrients is compacted or compacted by means of a compacting device 26 or a granulating device 26. granulated, whereby the grain size distribution can be adapted to the use of the product fraction S5 of the raw potassium salt, especially as fertilizer, with the grain size distribution being shifted towards larger diameters. For reasons of simplification, no distinction has been made between the compacting device 26 and the granulating device 26 in the drawing. If necessary and sensible, the product fraction S5 can be both compacted and granulated.

In the illustrated embodiment of the method, additives and/or organic and/or inorganic conditioning agents are added to the compacted and/or granulated product fraction S 6 using a third addition device 29. This also means that the S5 product fraction is prepared for use as fertilizer, for example.

It should be noted that, depending on the requirements for the potash product, the product fraction S5 can also be used directly as such without having to carry out the above-described steps above. In addition, the product fraction S5 can be subjected to one or more further purification steps such as crystallization. Such purification steps are usually carried out above ground and are suitable if a very high content, for example of potassium chloride, is to be provided.

In Figure 2, a second embodiment of a method according to the invention for processing raw potassium salts is also shown based on a basic representation. Since most of the steps of the method according to the second exemplary embodiment are similar to those of the method according to the first exemplary embodiment, only the differences will be discussed below.

After extraction, the raw potassium salt z S 1 obtained is also ground and sieved in the grinding and sieving device 16 in the second embodiment of the method. Based on the degree of adhesions of the obtained raw potash salt S 1, it is determined to what particle size the obtained raw potassium salt z S 1 should be ground and/or sieved. As an example, it should be mentioned that a particle size of at least 10 mm was determined for a potassium raw salt z S 1 that was examined in more detail in this regard.

The ground potassium raw salt z S2 is now separated into an intermediate fraction S7 and a second residue fraction S9 using a sensor-assisted sorting device 30. The second residue fraction S9, like the first residue fraction S4, is introduced into underground cavities 22, while the intermediate fraction S7 in this case is ground and/or sieved by means of a further grinding and/or sieving device 32.

As mentioned, the raw potassium salt z S 1 obtained in the grinding and sieving device 16 is reduced to a particle size of at least 10 mm ground and/or sieved. Such a particle size is usually too coarse for a marketable potash product, so that the intermediate fraction S7 can be brought to the desired particle size in the further grinding and/or sieving device 32. This results in the product fraction S5, which is conveyed by means of a shaft system 24 into the above-ground area 12, i.e. to the earth's surface 10, and can be further processed in the manner described.

It should be mentioned at this point that several sensor-assisted sorting steps can also be carried out one after the other (not shown). Between these sorting steps it may be advisable to carry out a grinding and/or sieving step. In addition, depending on the type of sorting step carried out, a product or intermediate fraction that is further processed and a residue fraction that is mixed will not necessarily always be obtained, but two product or intermediate fractions can also be obtained, which are separated from one another and typically be further processed into different products.

In Figure 3, a third embodiment of a method according to the invention for processing raw potassium salts is also shown based on a basic representation. Since most of the steps of the method according to the third exemplary embodiment are similar to those of the method according to the first exemplary embodiment, only the differences will be discussed below.

After extraction, the obtained potassium raw salt z S 1 is ground and sieved in the grinding and sieving device 16 as mentioned. seventh. However, the raw potassium salt z S 1 is not ground as finely as is the case in the first embodiment of the process. The larger grain class of the ground and sieved potassium raw salt z S2a is fed to a sensor-assisted sorting device 30, where sensor-assisted sorting is carried out. This sensor-assisted sorting cannot be used effectively if the particle size is too small. The smaller grain class S2b is fed directly to the further grinding and/or sieving device 32. The ratio between S2a and S2b, for example the ratio of the mass flows, can in principle be freely chosen. In particular, S2a or S2b can also be chosen to be “zero”. Usually, the ratio between S2a and S2b is chosen based on the existing conditions of the method.

The ground and sieved raw potassium salt z S2a is separated there into an intermediate fraction S7 and a second residue fraction S9. The second residue fraction S9, like the first residue fraction S4, is introduced into underground cavities 22, while the intermediate fraction S7 in this case is ground and/or sieved by means of a further grinding and/or sieving device 32. In the further grinding and/or sieving device 32, both the smaller grain class S2b and the intermediate fraction S7 are comminuted to such an extent that they can be electrostatically charged and separated in the electrostatic separating device. The further comminution step in the further grinding and/or sieving device 32 is necessary because in the separating device 20 the raw potassium salt z must be present in a significantly smaller particle size than in the sensor-assisted sorting device 30. Depending on the conditions of the process, the sensor-assisted sorting step can also be carried out above ground. The ground and/or the sieved intermediate fraction S 8 is then fed to the first addition device 18, where an organic and/or inorganic conditioning agent is added to it. The steps carried out below correspond to those described for the first embodiment of the method.

The essential steps of the method according to the invention according to the first exemplary embodiment are shown again in FIG. The obtained potassium raw salt z S 1 is ground and/or sieved using the grinding and/or sieving device 16, then the conditioning agent is added using the first adding device 18 and is electrostatically charged in the charging device 19. For the sake of simplicity, the addition device 18 and the charging device 19 are shown as a unit in FIG. During these steps, dedusting E is carried out. The electrostatic charging of the conditioned potassium raw salt z S3 takes place by contacting and setting a defined temperature and humidity.

The charged potassium raw salt z S3 is separated in a three-stage separation in the electrostatic separation device 20, which for this purpose has a first separation stage 201, a second separation stage 202 and a third separation stage 203. The separating device can be designed, for example, as an electrostatic free-fall separator. Here, the charged raw potassium salt z trickles in free fall through a high-voltage field, the positively and negatively charged particles are repelled from the poles according to their charge. attracted and deflected from their vertical direction of fall. Particles that do not have a clear charge follow the vertical direction of free fall and are fed back to the feed fraction. At the end of the fall path, at least two material flows are created, each of which has the enrichment of a valuable material. The positive pole and negative pole of the separating device 20 are designed as rotating tubes made of an electrically conductive material (not shown). It should be noted that the electrostatic separator 20 can also be designed in another way.

The electrostatic separation process can be carried out in one or more stages. The multi-stage electrostatic separation process consists of a combination of several separation stages, which are connected in such a way that a residue fraction and a concentrate are obtained in the first separation stage 201. The concentrate from the first separation stage 201 is then separated again in the second separation stage 202, with the low-recyclable fraction obtained being returned to the first separation stage 201 and the higher-recyclable fraction being fed into the third separation stage 203 as feed material. At the third separation stage 203, the low-recyclable fraction is returned to the second separation stage 202 and the high-recyclable product fraction S5 is discharged. The two experiments described below were carried out accordingly. All proportions are in weight. -% stated unless otherwise mentioned.

Attempt 1:

According to experiment 1, the raw potash salt z obtained underground from a first deposit was first ground to ensure a sufficient degree of digestion, which is of crucial importance for the electrostatic separation. The grain size range set here was <1.0 mm. After grinding, conditioning takes place with the addition of conditioning agents common for halite separation and the electrostatic charging of the minerals.

The compositions of the conditioned and charged potassium raw salt S3 (feed fraction), the product fraction S5 and the first residue fraction S4 are listed in the table below.

Table 1: Composition of the feed fraction S3, the product fraction S5 and the first residue fraction S4

Using this method, a batchable first residue fraction S4 can be obtained. A residue fraction capable of being offset can be understood as meaning a fraction in which the proportion of potassium chloride and/or magnesium oxide is so low that purification is no longer economical. The sylvine and kieserite yield in product fraction S5 was 86.7%/93.4% in this example. The halite recovery in the residue fraction was 91.7%. It has been shown that halite (sodium chloride) can be effectively separated using a three-stage process, so that a batchable first residue fraction and a product fraction S5 enriched in sylvin (potassium chloride) and kieserite (magnesium sulfate with water of crystallization, MgSO ^O) are obtained.

Attempt 2:

Experiment 2 was carried out in the same way as experiment 1, but the raw potash salt was obtained from a second deposit.

Table 2: Composition of the feed fraction S3, the product fraction S5 and the first residue fraction S4

With this procedure, a batchable first residue fraction S4 can be obtained. The sylvin yield in product fraction S5 was 94.5% in this example. The halite recovery in the first residue fraction S4 was 90%. A first exemplary embodiment of a sensor-assisted sorting device 30 is shown in FIG. 5, which can be used for the method according to the invention.

To separate different material flows, sensor-based sorting takes advantage of the fact that their components differ in at least one separation criterion. The separation criteria are in particular physical properties such as density, color, reflectivity or transmittance, which can be detected without contact by electromagnetic radiation.

The sorting device 30 can be designed as a belt sorter (not explicitly shown). The starting material is first placed on a conveyor belt for feeding and separation. The separation is intended to provide a monolayer of the ground potassium raw salt S2 so that each particle can be detected by the sensor unit of the sorting device 30. The material flow is then guided via the conveyor belt to the sensor unit. Here the specific material properties of the individual components are recognized by the sensor system. Using a discharge device (not shown) that works with compressed air, the material flow is divided into at least two material flows according to the material types.

Instead of the belt sorter described above, a chute sorter can also be used.

The sensor unit of the sorting device 30 according to the first exemplary embodiment comprises a near-infrared sensor 34. Using a near-infrared sensor 34, mineral phases containing crystal water can be detected, for example kieserite and accompanying minerals such as kainite, carnallite and leonite. Attempt 3:

The raw potash salt was obtained from a first seam and a second seam. The sorted particle size range was 20 - 40 mm.

Table 3: Composition of the feed fractions of the raw potash salt from seams 1 and 2

Table 4: Mass output and proportion of magnesium salts, indicated as magnesium oxide, in the product fraction (intermediate fraction S7 based on Figure 3) and the second residue fraction S9 after sorting with an NIR sensor

The results show the possibility of separating kieserite in particular (assessed indirectly via the MgO content) from a hard salt using a sensor-based sorting device 30 with a near-infrared sensor 34 (see Figure 5). The Kieserite output in the product fraction was 88 or 74%.

A second exemplary embodiment of a sorting device 30 is shown in FIG. 6, which can be used for the method according to the invention. The sorting device 30 according to the second exemplary embodiment comprises an optical sensor 36. By means of optical sensors 36, components of different colors can be easily separated from a raw potassium salt, for example clay.

Attempt 4:

In experiment 4, the dry separation of clay-containing components from a mineral mixture was examined using a sensor-assisted sorting device 30 according to FIG. 6. The sorted particle size range was 5 - 20 mm.

Table 5: Composition of the task group

Table 6: Mass output in terms of clay separation

Table 6 shows that an output of > 90% for Sylvin and > 80% for Kieserite could be achieved.

Sorting devices 30 with an optical sensor 36 are particularly suitable for mineral fractions with a high clay content (> 2.5% / clay = muscovite + llite + kaolinite + chlorite + clinochlor), which can be prepared using standard processing (electrostatic separation, flotation or Hot dissolving processes) cannot be processed or can only be processed with great technical effort, to make them available for standard processing. The stated composition of the clay refers to the present clay and is therefore to be regarded as exemplary. Since there are a large number of clay minerals, the clay can also have a significantly different composition.

A third exemplary embodiment of a sorting device 30 is shown in FIG. 7, which can be used for the method according to the invention. In this case, the sorting device 30 is designed as an X-ray transmission sorter 38 and has an X-ray sensor 40. Attempt 5:

Experiment 5 examined the separation of halite from a mineral mixture by means of sensor-assisted sorting using an X-ray sensor 40 (Experiments 5.1 to 5.5). The starting material for the experiments was raw potash salt S2, which was pre-crushed underground by a crusher after blasting. For sorting, two particle fractions were examined, 20 - 40 mm and 40 - 60 mm.

Table 7: Output in terms of halite and sylvine separation

The results show that offset amounts of > 30% are possible depending on the particle size (degree of intergrowth) and the detector setting. The yield of recyclable materials in product fraction S5 is > 90%. The K2O content of the residue fraction is so low that in most cases it can no longer be purified economically. It is therefore usually capable of being offset.

In experiments 5.6 and 5.7, the separation of sylvin from a mineral mixture was examined using sensor-assisted sorting with a particle fraction of 20 to 45 mm. reference character list

10 Earth surface

12 surface area

14 underground area

16 grinding and/or sieving device

18 first addition device

19 On charging device

20 separation device

201 - 203 separation stages of separation device

22 cavity

24 shaft system

26 compaction device, granulation device

27 bypass

28 second addition device

29 third addition device

30 sensor-based sorting device

32 additional grinding and/or sieving devices

34 near infrared sensor

36 optical sensor

38 X-ray transmission sorters

40 X-ray sensor

E Dust removal

51 Kalirohsal e.g

52 ground potassium raw salt e.g

S2a larger grain class of the ground potassium raw salt

S2b smaller grain class of the ground potassium raw salt

53 conditioned potassium raw salt e.g

54 first residue fraction 55 product fraction

S5a enriched product fraction

56 compacted product fraction

57 intermediate fraction S 8 ground and/or sieved intermediate fraction

S 9 second residue fraction

Claims

Patent claims

1. Process for processing raw potash salts, comprising the following steps:

- Underground extraction of raw potash salts (Sl) by cutting extraction and/or by drilling and blasting,

- Grinding and/or sieving the raw potash salts (Sl) obtained using a grinding and/or sieving device (16), and

- Sensor-assisted sorting of the ground and/or sieved raw potash salts (S2) into an intermediate fraction (S7) and a second residue fraction (S9) by means of a sensor-assisted sorting device (30).

2. The method according to claim 1, characterized in that the sorting device (30) comprises an X-ray transmission sorter (38) with an X-ray sensor (40) and the step of sensor-assisted sorting is carried out using an X-ray transmission measurement by means of the X-ray transmission sorter (38).

3. The method according to any one of claims 1 or 2, characterized in that the sorting device (30) comprises an optical sensor and the step of sensor-assisted sorting is carried out using an optical measurement by means of the optical sensor (36).

4. Method according to one of the preceding claims, characterized in that the sorting device (30) comprises a near-infrared sensor (34) and the step of Sensor-assisted sorting is carried out using a near-infrared measurement using the near-infrared sensor (34). Method according to one of the preceding claims, characterized in that the steps

- grinding and/or sieving the raw potash salts (Sl) obtained and

- the sensor-based sorting of the ground and/or sieved raw potash salts (S2) can be carried out underground. Method according to one of the preceding claims, comprising the following steps:

- Grinding and/or sieving the intermediate fraction (S7) by means of a further grinding and/or sieving device (32) to obtain a product fraction (S5) or a further intermediate fraction. Process for processing raw potash salts, comprising the following steps:

- Grinding and/or sieving the raw potash salts (Sl) obtained using a grinding and/or sieving device (16),

- Sensor-assisted sorting of the ground and/or sieved raw potash salts (S2a) into an intermediate fraction (S7) and a second residue fraction (S9) by means of a sensor-assisted sorting device (30),

- Grinding and/or sieving the intermediate fraction (S7) using a further grinding and/or sieving device - adding organic and/or inorganic conditioning agents to the ground and/or sieved intermediate fraction (S8) by means of a first addition device (18),

- electrostatic charging of the conditioned raw potassium salts (S3) by means of a charging device (19), and

- Separating the electrostatically charged raw potassium salts into a product fraction (S5) and a first residue fraction (S4) using the electrostatic separation device (20). Method according to claim 7, characterized in that

- the steps o of grinding and/or sieving the raw potash salts obtained (Sl) and the intermediate fraction (S7), o of the sensor-assisted sorting of the ground and/or sieved raw potash salts (S2) o of adding organic and/or inorganic conditioning agents to the ground ones and/or sieved raw potash salts (S2) and o the electrostatic charging of the conditioned raw potash salts (S3) and o separation of the electrostatically charged raw potash salts can be carried out underground. Method according to one of the preceding claims or according to one of claims 7 or 8, characterized in that

- the first residue fraction (S4) and/or

- the second residue fraction (S9) is introduced into underground cavities (22). Method according to one of claims 7 to 9, characterized by the following step:

- Adding nutrients to the product fraction (S5) using a second addition device (28). Method according to one of claims 7 to 9 or claim 10, characterized by the following step:

- Compacting and/or granulating the product fraction (S5) or the nutrient-enriched product fraction (5a) by means of a compacting device (26) or a granulating device (26). Method according to one of claims 10 or 11, characterized by the following step:

- Adding additives and/or organic and/or inorganic conditioning agents to the compacted and/or granulated product fraction (S6) using a third addition device (29). Method according to one of claims 10 to 12, characterized in that

- the step of adding nutrients to the product fraction (S5) or

- the steps o of adding nutrients to the product fraction (S5) and o of compacting and/or granulating the product fraction (S5) or

- the steps o of adding nutrients to the product fraction (S5), o compacting and/or granulating the product fraction (S5) and o adding additives and/or organic and/or inorganic conditioning agents on the surface. Use of a sorting device (30), which comprises an X-ray transmission sorter (38) with an X-ray sensor (40), for separating sodium chloride, in particular in the form of halite, from raw potassium salt and in particular from sylvin.