Method for processing potash ores

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

[0001] Process for the preparation of crude potash salts

[0002] The present invention relates to a process for processing crude potash salts.

[0003] It is known to produce a marketable potash product from crude potash salts from potash deposits using wet processing methods such as flotation and hot dissolving processes with subsequent crystallization and / or an evaporation process. In the following, a marketable potash product is understood to mean a product containing potassium chloride or potassium chloride and magnesium sulfate with a sodium chloride content of < 30 wt.%, preferably < 15 wt.%, and ideally < 5 wt.%.

[0004] Due to the fact that at least one drying step is necessary in the wet processing of crude potash salts, the energy requirement of such processing methods is correspondingly high.

[0005] The processing of crude potash salts is usually carried out in above-ground facilities. Disadvantages, however, include the land use required for the corresponding facilities, the above-ground stockpiling, the resulting changes to the landscape, and the need for sufficiently large shafts. The financial outlay for wet processing is correspondingly high.

[0006] For the relevant prior art, reference is made to DE 10 2017 125 467 A1, 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 process for processing crude potash salts, which makes it possible to remedy the above-mentioned disadvantages and, in particular, to create the possibility of carrying out the process underground.

[0007] This object is achieved by the features specified in claims 1, 7 and 14. Advantageous embodiments are the subject of the dependent claims.

[0008] One embodiment of the invention relates to a process for processing crude potash salts, comprising the following steps:

[0009] - Underground extraction of crude potash salts by cutting and / or drilling and blasting,

[0010] - grinding and / or sieving the extracted potash crude salts using a grinding and / or sieving device,

[0011] - Adding organic and / or inorganic conditioning agents to the ground and / or sieved crude potash salts by means of a first addition device,

[0012] - electrostatic charging of the conditioned crude potash salts by means of a charging device, and

[0013] - Separating the electrostatically charged crude potash salts into a product fraction and a first residue fraction by means of the electrostatic separation device.

[0014] The electrostatic charging of crude potash salts can be achieved, for example, by means of triboelectric charging, for which reference is made to DE 10 2017 218 206 A1. The conditioning agents serve to exchange charges of the ground and / or sieved crude potash salts, thereby promoting electrostatic charging. The steps of the process according to the invention according to the previously defined embodiment are exclusively "dry" steps that do not require the use of liquid, in particular water, whereas the flotation and hot dissolving steps mentioned at the outset are liquid-based, especially water-based. The "dry" process according to the invention therefore omits the drying process, which has a high energy requirement.As mentioned above, the prior art processes frequently involve evaporation and / or crystallization processes, which can be dispensed with in the process according to the invention. The associated energy requirement is eliminated.

[0015] Depending on the design of the liquid-based processing process, a certain loss of the product fraction due to dissolution almost always occurs, which cannot occur in the dry process.

[0016] In this respect, the process according to the invention is more energy-efficient than the processing methods mentioned above, thus achieving ecological and economic advantages. In particular, the invention allows the carbon dioxide footprint in the production of marketable potash products to be reduced.

[0017] It should be noted that the term "first residue fraction" should not be understood to mean that a second or further residue fraction will necessarily be produced.

[0018] According to a further embodiment, the step of grinding and / or sieving the obtained

[0019] Potassium crude salts underground or

[0020] - the steps of o grinding and / or sieving the obtained crude potash salts and o adding organic and / or inorganic conditioning agents to the ground and / or sieved crude potash salts or

[0021] - the steps of o grinding and / or sieving the obtained crude potash salts and o adding organic and / or inorganic conditioning agents to the ground and / or sieved crude potash salts and o electrostatically charging the conditioned crude potash salts or

[0022] - the steps of o grinding and / or sieving the obtained potash crude salts and o adding organic and / or inorganic conditioning agents to the ground and / or sieved potash crude salts and o electrostatically charging the conditioned potash crude salts and o separating the electrostatically charged potash crude salts are carried out underground.

[0023] In contrast to the wet processing methods mentioned above, all steps of the process according to the invention can be carried out underground with comparatively little effort. However, it is also possible to carry out only certain steps underground. The term "underground" is often used synonymously with the terms "underground" and "mining". The above-ground land use and the impact on the landscape are reduced. Typically, the mining effort decreases the more steps are carried out underground, so that the relevant shaft systems can be smaller, which benefits the economic efficiency of the process.

[0024] According to a further embodiment, the following steps can be carried out between the step of grinding and / or sieving the obtained crude potash salts and the step of adding organic and / or inorganic conditioning agents:

[0025] - sensor-assisted sorting of the ground and / or sieved crude potash salts into an intermediate fraction and a second residue fraction by means of a sensor-assisted sorting device,

[0026] - grinding and / or sieving the intermediate fraction by means of a further grinding and / or sieving device, and

[0027] - Adding organic and / or inorganic conditioning agents to the ground and / or sieved intermediate fraction by means of the first addition device.

[0028] By combining separation by electrostatic charging with sensor-assisted sorting, marketable potash products can be produced from crude potash salts, typically sylvinite, carnallitite, polyhalitic hard salts, or kieseritic hard salts, with comparatively low energy input. Sensor-assisted sorting can be carried out either underground or above ground. The subsequent steps of grinding and / or screening, as well as the addition of a conditioning agent, serve to prepare the intermediate fraction for electrostatic separation.

[0029] 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.

[0030] It has been found that sodium chloride (NaCl), particularly in the form of halite, can be easily separated from crude potash and particularly from sylvinite (potassium chloride, KCl) using an X-ray transmission sorter.

[0031] 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 by means of the optical sensor.

[0032] Cameras can be used in particular as optical sensors, which can be equipped with wavelength-dispersive elements and suitable spectral cameras, for example, and in simple embodiments also with optical filters. It has been found that optical sensors are particularly effective for separating components with different colors, for example evaluated on the basis of a wavelength-dependent spectrum, from a crude potash salt, such as clay. Clay can be understood as a mixture of muscovite, illite, kaolinite, chlorite and clinochlore, although other compositions can also be referred to as clay. Clay is not desired in the product in most cases.

[0033] In a further embodiment, the sorting device may comprise a near-infrared sensor and the step of sensor-assisted sorting may be carried out using a near-infrared measurement by means of the near-infrared sensor.

[0034] The use of near-infrared sensors (also known as NIR sensors) enables, in particular, the separation of mineral phases containing hydration water (e.g., kieserite, carnallite) from the potassium salt. The selection of the appropriate near-infrared sensor and the wavelength used by the near-infrared sensor in question are based on the boundary conditions of the respective application and, in particular, on the composition of the mineral phases to be separated.

[0035] According to a further embodiment,

[0036] - the first residue fraction and / or

[0037] - the second residue fraction is introduced into underground cavities.

[0038] Because the material is placed in underground cavities, also known as backfilling, surface stockpiling is no longer necessary. Furthermore, the residue fractions do not need to be transported to the surface (above ground), which means that the corresponding shafts can be smaller. Furthermore, no energy is required to transport the residue fractions to the surface. A more advanced design is characterized by the following step:

[0039] - Adding nutrients to the product fraction by means of a second addition device.

[0040] The effectiveness of the fertilizer can be increased by adding nutrients such as biostimulants, micronutrients, sulfur, boron, zinc and / or manganese salts.

[0041] For a further implementation, the following step may be appropriate:

[0042] - Compacting and / or granulating the product fraction or the nutrient-enriched product fraction by means of a compacting device or a granulating device.

[0043] Compacting and / or granulation are used to bring the product fraction to the desired grain size or particle size distribution. For example, when using potash products as fertilizers, it is advisable not to go below a certain grain size, among other things to prevent the applied fertilizer particles from being blown away by the wind. To be absorbed by 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 to the soil can be achieved with the appropriate choice of grain size.

[0044] In a further developed embodiment, the process may comprise 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.

[0045] The additives can be used to influence the physical properties of the product fraction, such as flowability and storage stability. Dust and caking behavior can be adjusted through post-treatment with organic and / or inorganic conditioning agents.

[0046] In a further developed embodiment, the following step(s) can be carried out above ground:

[0047] - the step of adding nutrients to the product fraction or

[0048] - the steps of o adding nutrients to the product fraction and o compacting and / or granulating the product fraction or

[0049] - 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.

[0050] Since the steps mentioned in this embodiment of the proposed process are usually optional and therefore not the entire product fraction is subjected to these process steps, it is advisable to carry out some or all of the steps above ground. This eliminates the need to transport the nutrients, additives, and / or conditioning agents underground and then back to the surface with the appropriately treated product fraction after the aforementioned steps have been carried out.

[0051] An implementation of the invention relates to a method for processing crude potash salts, comprising the following steps:

[0052] - Underground extraction of crude potash salts by cutting and / or drilling and blasting,

[0053] - grinding and / or sieving the extracted crude potash salts by means of a grinding and / or sieving device, and

[0054] - Sensor-assisted sorting of the ground and / or sieved crude potash salts into an intermediate fraction and a second residue fraction or a further intermediate fraction by means of a sensor-assisted sorting device.

[0055] It is not mandatory to use the electrostatic separation device for processing the crude potash salts.

[0056] Depending on the nature of the potash crude mined underground, it may be advisable to perform one or more sensor-assisted sorting processes on the ground and / or screened potash crude instead of separating electrostatically charged potash crude. The sensor-assisted sorting devices already mentioned can be used for this purpose, 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" should therefore be understood to mean that a first residue fraction does not necessarily have to be present. The terms "first residue fraction" and "second residue fraction" serve to better distinguish between them and do not imply any particular relationship. Sensor-assisted sorting can be carried out either underground or above ground.

[0057] As mentioned, just one sensor-assisted sorting or several sensor-assisted sorting steps can be carried out. For example, the first sensor-assisted sorting step can be the separation of clay using an optical sensor, followed, for example, by the separation of mineral phases containing water of hydration, such as kieserite or carnallite, using a near-infrared sensor. The final step can be sorting using an X-ray transmission sorter to separate sodium chloride (NaCl), particularly in the form of halite, from the crude potash salt. Other combinations of these sorting steps are also conceivable. For further information, please refer to the above comments on sensor-assisted 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 potash crude salt, the kieserite-containing fraction can also be further processed.

[0058] The particle size at which sorting is carried out depends on the degree of intergrowth of the extracted potash crude salt. The optimum particle size can only be determined by appropriate tests on the extracted potash crude salt. It is important to ensure that the particles of the potash crude salt to be sorted must not be too small. One of the reasons for this is that with sensor-assisted sorting, every single particle has to be detected by the sorting device. For this to happen, a monolayer of the particles to be sorted must be present. The finer the potash crude salt is ground, the higher the number of particles per volume unit. As the number of particles increases, the time required to separate a volume unit of potash crude salt also increases, which reduces throughput and makes sorting increasingly less economical.

[0059] For a potash crude salt z which has been examined in more detail, sensor-assisted sorting can be carried out economically for a particle size of, for example, larger than 10 mm or larger than 15 mm.

[0060] Further training stipulates that the steps

[0061] - grinding and / or sieving of the extracted potash crude salts and

[0062] - the sensor-assisted sorting of the ground and / or sieved potash crude salts is carried out underground.

[0063] In particular, the use of land above ground and the associated impact on the landscape are kept to a minimum. Dust and noise emissions, particularly during milling, are less disruptive underground.

[0064] According to further training, the procedure includes the following step:

[0065] - 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.

[0066] As mentioned, depending on the degree of intergrowth of the crude potash salt, sensor-assisted sorting can be carried out economically, for example, with a particle size of 10 mm or larger. However, such particle sizes are generally too coarse for a marketable potash product. Re-grinding and / or sieving of the intermediate fraction serves to provide the desired particle size distribution for the potash product.

[0067] As also mentioned, several sorting steps can be performed consecutively. For example, if the clay is separated in one sorting step, the volume of the fraction to be further processed is reduced, so it may be useful to grind and / or sieve this fraction to be further processed (another intermediate fraction) before the following sensor-based sorting step, for example, to increase the degree of separation.

[0068] In principle, the sensor-assisted sorting steps can be performed both underground and above ground. Whether some or all of the sensor-assisted sorting steps are performed underground or above ground depends on the constraints of the respective application.

[0069] According to a further development of the procedure, the steps

[0070] - grinding and / or sieving of the recovered crude potash salts ( S1 ) and the intermediate fraction ( S7 ),

[0071] - sensor-assisted sorting of ground and / or sieved crude potash salts (S2)

[0072] - adding organic and / or inorganic conditioning agents to the ground and / or sieved crude potash salts (S2) and

[0073] - the electrostatic charging of the conditioned crude potash salts (S3) and

[0074] - Separation of the electrostatically charged potash crude salts is carried out underground. In particular, the area consumed above ground and the associated impact on the landscape are kept to a minimum. The noise and dust emissions generated during the processing of the extracted potash crude salts are less disruptive underground than above ground.

[0075] One embodiment of the invention relates to the use of a sorting device comprising an X-ray transmission sorter with an X-ray sensor for separating sodium chloride (NaCl), particularly in the form of halite, from potash crude salt and particularly from sylvinite (potassium chloride, KCl). It has been found that sodium chloride (NaCl), particularly in the form of halite, can be easily separated from potash crude salt and particularly from sylvine (potassium chloride, KCl) by means of an X-ray transmission sorter.

[0076] One embodiment of the invention relates to the use of the product fraction as a fertilizer, which is obtained by means of a process according to one of the previously described embodiments.

[0077] The technical effects and advantages that can be achieved with the use of the product fraction obtained by 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 with the processing methods mentioned above, so that ecological and economic advantages can be achieved. In particular, the carbon footprint during the production of the fertilizer can be reduced. Exemplary embodiments of the invention are explained in more detail below with reference to the attached drawings. They show

[0078] Figure 1 is a schematic representation of a first embodiment of the method according to the invention,

[0079] Figure 2 shows a schematic representation of a second embodiment of the method according to the invention,

[0080] Figure 3 is a schematic representation of a third embodiment of the method according to the invention,

[0081] Figure 4 shows a schematic representation of the essential steps for carrying out a separation using the electrostatic separation device,

[0082] Figure 5 is a schematic representation of a first embodiment of a sorting device,

[0083] Figure 6 is a schematic representation of a second embodiment of a sorting device,

[0084] Figure 7 is a schematic representation of a third embodiment of a sorting device.

[0085] Figure 1 shows a first embodiment of a method according to the invention for processing potash crude salts based on a schematic diagram. The processing of potash crude salts is carried out with the aim of providing a marketable potash product in which the sodium chloride content is less than 30 wt.% and the proportion of potassium chloride and, optionally, the proportion of magnesium sulfate is to be increased. The processed potash crude salt is typically used as a fertilizer.

[0086] In Figure 1, an earth surface 10 is marked, which divides the representation into an above-ground area 12 and an underground area 14.

[0087] In the underground area 14, potash crude salt z S 1 is extracted in a first step by means of cutting extraction and / or by drilling or blasting. In a second step, the potash crude salt z S 1 thus obtained is ground and / or screened underground using a grinding and / or screening device 16. In the process, the potash crude salt z S 1 is brought to a grain size distribution at which the subsequent steps, which are discussed below, can be carried out optimally or almost optimally. Also underground, conditioning agents, which can be organic or inorganic in nature and mixtures thereof, are added to the ground and / or screened potash crude salt z S2 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 crude potash salt S2 is charged electrostatically, here triboelectrically. The conditioned and charged crude salt S3 is then separated in a separating device 20 based on the polarity of the particles of the charged crude potash salt into a first residue fraction S4 and a product fraction S5. The first residue fraction S4 is introduced into underground cavities 22, also referred to as backfilling. The product fraction S5 is conveyed by means of a shaft system 24 into the above-ground area 12, i.e. to the earth's surface 10. There, the product fraction S5 is enriched with nutrients, for example with micronutrients and / or biostimulants, by means of a second addition device 28.It should be noted that this step can be omitted depending on the desired properties of the potash product. Accordingly, a bypass 27 can be provided.

[0088] Subsequently, the product fraction S5 or the nutrient-enriched product fraction S5a is compacted or granulated by means of a compacting device 26 or a granulating device 26, whereby the grain size distribution can be adapted to the use of the product fraction S5 of the potash crude salt, in particular as a fertilizer, with the grain size distribution being shifted towards larger diameters. For reasons of simplification, no distinction has been made in the drawing between the compacting device 26 and the granulating device 26. If necessary and appropriate, the product fraction S5 can be both compacted and granulated.

[0089] 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 S6 using a third addition device 29. This also prepares the product fraction S5, for example, for use as a fertilizer.

[0090] It should be noted that, depending on the requirements of the potash product, the product fraction S5 can also be used directly as such, without the above-described above-ground steps. Furthermore, the product fraction S5 can be subjected to one or more further purification steps, such as crystallization. Such purification steps are typically carried out above ground and are suitable when a very high content of potassium chloride, for example, is required.

[0091] Figure 2 shows a second embodiment of a method according to the invention for processing crude potash salts, also in a schematic representation. Since most of the steps of the method according to the second embodiment are similar to those of the method according to the first embodiment, only the differences will be discussed below.

[0092] After extraction, the extracted potash crude salt z S 1 is also ground and sieved in the grinding and sieving device 16 in the second embodiment of the process. Based on the degree of intergrowth of the extracted potash crude salt S 1, the particle size to which the extracted potash crude salt z S 1 should be ground and / or sieved is determined. As an example, it should be mentioned that for a potash crude salt z S 1 examined in more detail in this regard, a particle size of at least 10 mm was determined.

[0093] The ground potash crude salt S2 is then separated into an intermediate fraction S7 and a second residue fraction S9 by means of a sensor-supported 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 is ground and / or screened by means of a further grinding and / or screening device 32.

[0094] As mentioned, the extracted potash crude salt S1 has been ground and / or screened in the grinding and screening device 16 to a particle size of at least 10 mm. 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 screening device 32. This produces 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.

[0095] It should be mentioned here that several sensor-assisted sorting steps can also be performed consecutively (not shown). It may be advisable to perform a grinding and / or screening step between these sorting steps. Furthermore, depending on the type of sorting step performed, not always one product or intermediate fraction is necessarily obtained for further processing and one residue fraction is added. Rather, two product or intermediate fractions may also be obtained, which are then processed separately and typically into different products.

[0096] Figure 3 also shows a third embodiment of a method according to the invention for processing crude potash salts in a schematic representation. Since most of the steps of the method according to the third embodiment are similar to those of the method according to the first embodiment, only the differences will be discussed below.

[0097] After extraction, the extracted potash crude salt z S 1 is ground and sieved in the grinding and screening device 16 as mentioned. However, the potash crude 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 screened potash crude 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 screening device 32. The ratio between S2a and S2b, for example the ratio of the mass flows, can in principle be freely selected. In particular, S2a or S2b can also be selected as "zero". Typically, the ratio between S2a and S2b is selected based on the existing conditions of the process.

[0098] The ground and screened potash crude salt 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 screened by means of a further grinding and / or screening device 32. In the further grinding and / or screening device 32, both the smaller grain class S2b and the intermediate fraction S7 are crushed to such an extent that they can be electrostatically charged and separated in the electrostatic separation device. The further crushing step in the further grinding and / or screening device 32 is necessary because the potash crude salt z must have a significantly smaller particle size in the separation device 20 than in the sensor-supported sorting device 30.Depending on the process conditions, the sensor-assisted sorting step can also be performed above ground. The ground and / or screened intermediate fraction S8 is then fed to the first addition device 18, where an organic and / or inorganic conditioning agent is added. The subsequent steps correspond to those described for the first embodiment of the process.

[0099] Figure 4 shows the essential steps of the method according to the invention in accordance with the first exemplary embodiment. The obtained crude potash salt S1 is ground and / or sieved by means of the grinding and / or sieving device 16, then the conditioning agent is added by means of the first addition device 18 and 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 single unit in Figure 4. During these steps, dust removal E is carried out. The electrostatic charging of the conditioned crude potash salt S3 takes place by contacting and adjusting a defined temperature and air humidity.

[0100] The charged potash crude salt 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 separation device can be designed, for example, as an electrostatic free-fall separator. The charged potash crude salt trickles through a high-voltage field in free fall, the positively and negatively charged particles are repelled or attracted by the poles according to their charge 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 into the feed fraction. In this way, at least two material streams are created at the end of the fall section, each of which has an enrichment in a valuable material.The positive and negative poles 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 separating device 20 may also be designed in other ways.

[0101] 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 resulting fraction which is low in valuable materials being returned to the first separation stage 201 and the fraction which is rich in valuable materials being fed as feed material to the third separation stage 203. In the third separation stage 203, the fraction which is low in valuable materials is returned to the second separation stage 202 and the product fraction which is rich in valuable materials is discharged. The two tests described below were carried out accordingly. All proportions are given in % by weight unless stated otherwise.

[0102] Attempt 1:

[0103] According to Experiment 1, the potash crude extracted underground from a first deposit was first ground to ensure a sufficient degree of extraction, which is crucial for electrostatic separation. The grain size range used here was < 1.0 mm. After grinding, conditioning was carried out with the addition of conditioning agents commonly used for halite separation, and the electrostatic charging of the minerals.

[0104] The compositions of the conditioned and charged crude potash salt S3 (feed fraction), the product fraction S5 and the first residue fraction S4 are listed in the following table.

[0105] Table 1 : Composition of the feed fraction S3 , the product fraction S5 and the first residue fraction S4

[0106] Using this process, a backfillable first residue fraction S4 can be obtained. A backfillable residue fraction can be understood as a fraction in which the proportion of potassium chloride and / or magnesium oxide is so low that purification is no longer economical. The sylvite and kieserite recovery in the product fraction S5 in this example was 86.7% and 93.4%. 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 backfillable first residue fraction and a product fraction S5 enriched in sylvite (potassium chloride) and kieserite (magnesium sulfate with water of crystallization, MgSO4O) are obtained.

[0107] Attempt 2:

[0108] Experiment 2 was conducted in the same way as Experiment 1, but the crude potash salt was extracted from a second deposit.

[0109] Table 2: Composition of the feed fraction S3, the product fraction S5 and the first residue fraction S4

[0110] With this procedure, a first residue fraction S4 suitable for backfilling can be obtained. The sylvite recovery in the product fraction S5 in this example was 94.5%. The halite recovery in the first residue fraction S4 was 90%. Figure 5 shows a first embodiment of a sensor-supported sorting device 30 that can be used for the method according to the invention.

[0111] Sensor-assisted sorting uses the fact that their components differ in at least one separation criterion to separate different material flows. These separation criteria are primarily physical properties such as density, color, reflectivity, or transmittance, which can be detected contactlessly using electromagnetic radiation.

[0112] 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 crude potash 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 detected by the sensor system. Using a discharge device (not shown) operating with compressed air, the material flow is divided into at least two material flows according to the material type.

[0113] Instead of the belt sorter described above, a chute sorter can also be used.

[0114] The sensor unit of the sorting device 30 according to the first embodiment comprises a near-infrared sensor 34. A near-infrared sensor 34 can be used to detect primarily mineral phases containing water of crystallization, for example, kieserite and accompanying minerals such as kainite, carnallite, and leonite. Experiment 3:

[0115] The crude potash salt was extracted from a first seam and a second seam. The sorted particle size range was 20–40 mm.

[0116] Table 3: Composition of the feed fractions of the crude potash salt from seams 1 and 2

[0117] Table 4: Mass yield and proportion of magnesium salts, expressed 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

[0118] The results demonstrate the feasibility of separating primarily kieserite (evaluated indirectly via the MgO content) from a hard salt using a sensor-assisted sorting device 30 with a near-infrared sensor 34 (see Figure 5). The kieserite recovery in the product fraction was 88% and 74%, respectively.

[0119] Figure 6 shows a second exemplary embodiment of a sorting device 30 that 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. Optical sensors 36 can be used to effectively separate components of different colors from a crude potash salt, for example, clay.

[0120] Attempt 4 :

[0121] In Experiment 4, the dry separation of clay-containing components from a mineral mixture was investigated using a sensor-assisted sorting device 30 as shown in Figure 6. The sorted particle size range was 5-20 mm.

[0122] Table 5 : Composition of the feed fraction

[0123]

[0124] Table 6 : Mass output with regard to clay separation

[0125] Table 6 shows that a recovery of > 90 % for sylvite and > 80 % for kieserite could be achieved.

[0126] Sorting devices 30 with an optical sensor 36 are particularly suitable for making mineral fractions with a high clay content (> 2.5% / clay = muscovite + illite + kaolinite + chlorite + clinochlore) available for standard processing, which cannot be processed by standard processing (electrostatic separation, flotation or hot dissolving processes) or can only be processed with great technical effort. The stated composition of the clay refers to the clay in question and is therefore to be regarded as an example. Since there is a large number of clay minerals, the clay can also have a significantly different composition.

[0127] Figure 7 shows a third exemplary embodiment of a sorting device 30 that 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. Experiment 5:

[0128] Experiment 5 investigated the separation of halite from a mineral mixture using sensor-assisted sorting with an X-ray sensor 40 (Experiments 5.1 to 5.5). The starting material for the experiments was crude potash salt S2, which was pre-crushed underground by a crusher after blasting. Two particle fractions were examined for sorting: 20-40 mm and 40-60 mm.

[0129] Table 7 : Application regarding halite and sylvine separation

[0130] The results show that, depending on the particle size (degree of intergrowth) and the detector settings, backfill quantities of > 30% are possible. The yield of valuable materials in the product fraction S5 is > 90%. The K2O content of the residue fraction is so low that it can no longer be economically purified in most cases. It is therefore usually suitable for backfilling.

[0131] In experiments 5.6 and 5.7, the separation of sylvite from a mineral mixture was investigated using sensor-assisted sorting with a particle size of 20 to 45 mm.

[0132] 10 Earth's surface

[0133] 12 above-ground area

[0134] 14 underground area

[0135] 16 Grinding and / or screening device

[0136] 18 first addition device

[0137] 19 On charging device

[0138] 20 Separator

[0139] 201 - 203 Separation stages of separating device

[0140] 22 Cavity

[0141] 24 mine shaft

[0142] 26 Compaction device, granulation device

[0143] 27 Bypass

[0144] 28 second drawbar device

[0145] 29 third addition device

[0146] 30 sensor-supported sorting device

[0147] 32 additional grinding and / or screening devices

[0148] 34 Near-infrared sensor

[0149] 36 optical sensor

[0150] 38 X-ray transmission sorters

[0151] 40 X-ray sensor

[0152] E Dust removal

[0153] 51 Potassium crude salt z

[0154] 52 ground potassium hydroxide

[0155] S2a larger grain class of ground potash crude salt

[0156] S2b smaller grain class of ground potash crude salt

[0157] 53 conditioned potassium hydroxide

[0158] 54 first residue fraction 55 product fraction

[0159] S5a enriched product fraction

[0160] 56 compacted product fraction

[0161] 57 Intermediate fraction S 8 ground and / or sieved intermediate fraction

[0162] S 9 second residue fraction

Claims

Patent claims 1. A process for processing crude potash salts, comprising the following steps: - Underground extraction of crude potash salts (Sl) by cutting extraction and / or drilling and blasting, - grinding and / or sieving the obtained crude potash salts (S1) by means of a grinding and / or sieving device (16), and - Sensor-assisted sorting of the ground and / or sieved crude potash salts (S2) into an intermediate fraction (S7) and a second residue fraction (S9) by means of a sensor-assisted sorting device (30).

2. 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. Method according to 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 by means of the near-infrared sensor (34). Method according to one of the preceding claims, characterized in that the steps - grinding and / or sieving of the extracted crude potash salts (Sl) and - the sensor-assisted sorting of the ground and / or sieved crude potash salts (S2) is carried out underground. A 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. A method for processing crude potash salts, comprising the following steps: - Underground extraction of crude potash salts (Sl) by cutting extraction and / or drilling and blasting, - grinding and / or sieving the obtained crude potash salts (Sl) by means of a grinding and / or sieving device (16), - Sensor-assisted sorting of the ground and / or sieved crude 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) by means of 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 crude potash salts (S3) by means of a charging device (19), and - Separating the electrostatically charged crude potassium salts into a product fraction (S5) and a first residue fraction (S4) by means of the electrostatic separating device (20). A method according to claim 7, characterized in that - the steps of o grinding and / or sieving the recovered crude potash salts (S1) and the intermediate fraction (S7), o sensor-assisted sorting of the ground and / or sieved crude potash salts (S2), o adding organic and / or inorganic conditioning agents to the ground and / or sieved crude potash salts (S2), and o electrostatically charging the conditioned crude potash salts (S3), and o separating the electrostatically charged crude potash salts are 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) by means of 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) by means of 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 of o adding nutrients to the product fraction (S5) and o compacting and / or granulating the product fraction (S5) or - the steps 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 is carried out above ground. Use of a sorting device (30) comprising an X-ray transmission sorter (38) with an X-ray sensor (40) for separating sodium chloride, particularly in the form of halite, from crude potash salt and particularly from sylvite.

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