CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority to U.S. Provisional Application No.

62/269,402 entitled "PROCESSING POTASSIUM CHLORIDE" and filed on December 18, 2015, which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

[0002] The present invention is related to processing potassium chloride, and more particularly to processing industrial grade potassium chloride to yield food grade potassium chloride.

BACKGROUND

[0003] Potassium chloride is usually obtained by extraction of potash derived from shaft mining or solution mining of the ore. Purification processes including hot leaching and recrystallization are typically used to remove soluble and insoluble impurities. The resulting potassium chloride is classified based on purity as fertilizer grade potassium chloride, industrial grade potassium chloride, or food grade potassium chloride.

SUMMARY

[0004] This specification describes technologies related to systems and methods for preparing food grade potassium chloride from industrial grade potassium chloride.

[0005] In a first general aspect, processing industrial grade potassium chloride to yield food grade potassium chloride includes at least one of (i) removing particles having a maximum dimension from the industrial grade potassium chloride and (ii) optically screening the industrial grade potassium chloride; and polishing the industrial grade potassium chloride to yield food grade potassium chloride.

[0006] Implementations of the first general aspect may include one or more of the following features.

[0007] In some embodiments, processing industrial grade potassium chloride includes removing particles having a maximum dimension (e.g., 0.5 cm) from the industrial grade potassium chloride. [0008] In some embodiments, optically screening the industrial grade potassium chloride includes imaging the industrial grade potassium chloride with a camera to identify particles with color characteristics that fall outside a selected range, and removing the particles so identified from the industrial grade potassium chloride. Optically screening the industrial grade potassium chloride may include removing impurities from the industrial grade potassium chloride.

[0009] Polishing the industrial grade potassium chloride typically includes contacting the industrial grade potassium chloride with a polishing fluid. The polishing fluid may include ozone in a sufficient amount to achieve an antimicrobial effect. In some cases, the polishing fluid is or includes water. In certain cases, the polishing fluid is or includes an alcohol, such as ethanol. A temperature of the polishing fluid may be less than 100°C, less than 40°C, or less than 20°C. Polishing the industrial grade potassium chloride may include spraying the industrial grade potassium chloride with a finishing fluid.

[0010] In some embodiments, polishing the industrial grade potassium chloride includes acoustic cavitation of the polishing fluid. The acoustic cavitation is typically sufficient to achieve an antimicrobial effect. The acoustic cavitation may be provided by an ultrasound generator or high pressure cavitation system. In certain

embodiments, polishing the industrial grade potassium chloride includes agitating the industrial grade potassium chloride in the polishing fluid.

[0011] Processing industrial grade potassium chloride may include drying the food grade potassium chloride, treating the industrial grade potassium chloride or the food grade potassium chloride with a UV light, heating the food grade potassium chloride to at least 200°C or 250°C, or any combination thereof.

[0012] In some embodiments, the industrial grade potassium chloride includes at least 98.0 wt% potassium chloride, at least 98.5 wt% potassium chloride, or up to 99 wt% potassium chloride. The food grade potassium chloride may include at least 99 wt% potassium chloride or at least 99.5 wt% potassium chloride. Particles of the industrial grade potassium chloride may have a minimum dimension of at least 0.1 cm, at least 0.3 cm, or at least 0.5 cm.

[0013] In some embodiments, processing the industrial grade potassium chloride occurs continuously. In certain embodiments, processing the industrial grade potassium chloride includes sorting at least 25 kg or at least 4000 kg of the industrial grade potassium chloride an hour.

[0014] The industrial grade potassium chloride typically remains in crystalline form. That is, processing the industrial grade potassium chloride does not completely dissolve the industrial grade potassium chloride, such that processing the industrial grade potassium chloride occurs in the absence of recrystallization.

[0015] In a second general aspect, a production line for processing industrial grade potassium chloride particles includes an optical screening system including a camera to image the industrial grade potassium chloride particles and a polishing system to polish the industrial grade potassium chloride particles.

[0016] Implementations of the second general aspect may include one or more of the following features.

[0017] In some embodiments, the production line includes an outlet operatively coupled to the camera and configured to receive particles with a color characteristic that falls outside a selected range. The production line may include a controller configured to identify particles with a color characteristic that falls outside a selected range.

[0018] In certain embodiments, the polishing system includes a chamber configured to contain a polishing fluid. The polishing fluid may include water, an alcohol, or a combination thereof. In some cases, the polishing fluid is or includes ethanol.

[0019] The polishing system may include a pump configured to recycle the polishing fluid. The polishing system typically includes a conveyor belt configured to translate the industrial grade potassium chloride particles through the chamber with the polishing fluid. In some cases, the polishing system includes an ultrasonic transducer operatively coupled to the chamber and configured to acoustically cavitate the polishing fluid. In certain cases, the polishing system includes sprayers configured to spray the industrial grade potassium chloride particles.

[0020] In some embodiments, the production line includes a screen to retain industrial grade potassium chloride particles having a minimum size. The production line may include blowers or air knifes for drying the industrial grade potassium chloride particles. In some cases, the production line includes a heater configured to heat the industrial grade potassium chloride particles to a temperature of at least 80°C or at least 250°C. In certain cases, the production line includes a moisture sensor configured to detect moisture in the industrial grade potassium chloride.

[0021] Advantages associated with the systems and methods for preparing food grade potassium chloride from industrial grade potassium chloride described herein include rapid and cost-efficient preparation of food grade potassium chloride, due at least in part to the avoidance of dissolving and recrystallizing the industrial grade potassium chloride.

[0022] The details of one or more implementations of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIGS. 1A and IB are portions of a flow chart depicting a process for preparing food grade potassium chloride from industrial grade potassium chloride.

[0024] FIGS. 2 A and 2B depict portions of a production line for processing industrial grade potassium chloride.

DETAILED DESCRIPTION

[0025] The present disclosure relates to systems and methods for preparing food grade potassium chloride from industrial grade potassium chloride. As used herein, "industrial grade potassium chloride" contains at least 95 wt% potassium chloride, with the remainder being impurities, some of which are soluble in water (soluble impurities) and some of which are insoluble in water (insoluble impurities). As used herein, and as required by Food Chemicals Codex. Ninth Edition (National Academy of Sciences, 2014), "food grade potassium chloride" contains not less than 99.0 wt% potassium chloride after drying or not less than 98.0 wt% of potassium chloride after drying when a sample contains added substances (e.g., anticaking agents), and no more than 5 mg/kg (e.g., not more than 5 ppm or 0.0005 wt%) heavy metals. As used herein, weight percentages of potassium chloride refer to potassium chloride on a dried basis. As described herein, potassium chloride in the solid state, including potassium chloride that has a powdered appearance, is understood to be in crystalline form. [0026] FIGS. 1 A and IB provide a flow chart showing a process 100 for preparing food grade potassium chloride from industrial grade potassium chloride. Process 100 typically occurs continuously, such that the industrial grade potassium chloride is provided as a process stream at a selected rate (e.g., at least 25 kg an hour, at least 1000 kg an hour, or at least 4500 kg an hour) to yield a corresponding product stream of food grade potassium chloride.

[0027] Referring to FIG 1A, in 102, fine particles ("fines") are removed from the industrial grade potassium chloride. The industrial grade potassium chloride is typically in the form of particles (e.g., "nuggets" or "rocks") of various shapes and sizes. The particles generally have a maximum size (e.g., a largest dimension) of up to 3 cm, up to 4 cm, up to 5 cm, or up to 8 cm. In this description, "potassium chloride" and "potassium chloride particles" are used interchangeably. The industrial grade potassium chloride includes at least 95 wt% potassium chloride, and in some cases, at least 98 wt%, at least 98.5 wt%, or up to 99 wt% potassium chloride. Removing fines from the process stream may include, for example, sifting the potassium chloride or contacting the potassium chloride with a screen or mesh defining openings to remove fines from the potassium chloride, while the potassium chloride to be processed is retained in the sifter or on the screen or mesh. In some examples, the openings have a minimum dimension of 0.1 cm, 0.3 cm, or 0.5 cm, such that particles of the potassium chloride to be processed have a minimum dimension of at least 0.1 cm, at least 0.3 cm, or at least 0.5 cm, respectively, and the fines have a maximum dimension of up to 0.1 cm, up to 0.3 cm, or up to 0.5 cm, respectively. The fines may be collected for further processing.

[0028] In 104, the potassium chloride is optically screened. Optically screening the potassium chloride may include, for example, imaging the potassium chloride with a camera to identify particles with color characteristics that fall outside a selected range, and removing the particles so identified from the process stream. The camera may include a video graphic array (VGA) charge-coupled device (CCD) sensor (e.g., A30 Series Smart Camera available from Datalogic). In one example, particles with "off-white" color characteristics are removed from the process stream.

[0029] In 106, the potassium chloride is polished. As used herein, "polishing" the potassium chloride generally refers to contacting the potassium chloride with a food grade polishing fluid (e.g., a liquid, a gas, or a combination thereof), mechanically abrading the potassium chloride (e.g., with a brush or other implement), agitating the potassium chloride (e.g., such that the potassium chloride particles contact each other), or any combination thereof. In some embodiments, contacting the potassium chloride with a food grade polishing fluid includes washing the potassium chloride with the food grade polishing fluid. Contacting the potassium chloride with a gas includes contacting the potassium chloride with air, carbon dioxide (e.g., liquid carbon dioxide), an inert gas such as nitrogen, or the like, or any combination thereof.

Contacting the potassium chloride with a liquid includes contacting the potassium chloride with a solvent such as water, an aqueous medium including water and one or more additives, an organic solvent, or any combination thereof. The organic solvent may include a non-polar organic solvent (e.g., hexane), a polar organic solvent, or any combination thereof. Examples of polar organic solvents include alcohols, such as methanol, ethanol, isopropanol, n-propanol, n-butanol, t-butanol, acetic acid, or formic acid. In some cases, the organic solvent includes an alkene, alkyne, alicyclic aliphatic hydrocarbon, aromatic hydrocarbon, alcohol, amine, ester, ether, ketone, nitrated or chlorinated hydrocarbon, or any combination thereof.

[0030] A polishing fluid used to polish the potassium chloride may be at a temperature up to 80°C (e.g., from below 0°C to 80°C). In some cases, the fluid is at ambient temperature (e.g., room temperature, less than 25°C, less than 20°C, or in a range from 10°C to 30°C or from 15°C to 25°C). During polishing, the potassium chloride is not completely dissolved in the fluid or recrystallized; however, some potassium ions and chloride ions may be removed from the potassium chloride particles during polishing (e.g., when the fluid is an aqueous medium). That is, the potassium chloride remains in crystalline form in process 100 to yield food grade potassium chloride in the absence of recrystallization.

[0031] Contacting the potassium chloride with a polishing fluid typically includes submerging the potassium chloride in the fluid, for example, by passing the potassium chloride on a conveyor belt through a chamber containing the polishing fluid to remove contaminants from the potassium chloride. In some cases, ozone may be combined with the polishing fluid to provide an antimicrobial effect and to promote disinfection and oxidation of contaminants. In some cases, the polishing fluid, the potassium chloride, or both are agitated to facilitate polishing. In one example, agitation is achieved by acoustic cavitation of the polishing fluid with an ultrasound unit. A dwell time of the potassium chloride in the polishing fluid may be in a range of 5 seconds to 60 seconds (e.g., 10 seconds to 30 seconds, or 15 seconds to 25 seconds). The ultrasonic treatment may be of sufficient power to achieve an antimicrobial effect. The dwell time may vary based on various factors, such as extent of contamination of the potassium chloride, desired throughput of the production line, and the like. After the potassium chloride is removed from the polishing fluid, the potassium chloride may be sprayed with a finishing fluid to remove surface contaminants. The finishing fluid may include a liquid, gas, or combination thereof as described with respect to the polishing fluid. The finishing fluid may be the same as or different than the polishing fluid. In some cases, the polishing fluid, the runoff from the finishing fluid, or both may be collected, filtered, recycled, and reused in the polishing process.

[0032] In 108, the potassium chloride is dried to remove surface moisture. Drying (at least partially drying), as well as removing foreign matter on the surface of the potassium chloride, may be achieved by contacting the potassium chloride with a gas such as air, nitrogen, superheated steam, and the like, or any combination thereof. The gas may be provided via a blower, an air knife, or as a compressed gas. The gas may be dried prior to use. In some cases, the potassium chloride retains some moisture (e.g., up to 0.5 wt% or up to 0.2 wt%) after drying.

[0033] In 110, the potassium chloride is disinfected with a UV treatment.

[0034] In 112, the potassium chloride is heated to remove additional moisture and to provide an antimicrobial effect. Heating may be achieved by exposing the potassium chloride to radiant heat. Heating may include increasing a temperature of the potassium chloride to at least at least 80°C or 125°C, thereby removing the majority of the remaining moisture and effectively sterilizing the potassium chloride.

[0035] Referring to FIG IB, in 114, the potassium chloride is passed through a magnet (e.g., a rare earth magnet) to remove magnetic contaminants (e.g., metal shards from the production line).

[0036] In 116, the potassium chloride is milled to reduce the particle size of the potassium chloride. In some cases, a maximum dimension of the resulting potassium chloride is in a range of about 25 μιτι to about 85 μιτι.

[0037] In 118, the potassium chloride is sifted to yield a product having a range of particle sizes selected for the finished food product applications. [0038] In 120, the potassium chloride is passed through a second magnet (e.g., a rare earth magnet) to remove magnetic contaminants (e.g., metal shards from the production line).

[0039] In 122, one or more additives may be combined with the potassium chloride. The resulting potassium chloride may contain up to 1.0 wt% additives.

Additives may include, for example, one or more food grade anticaking agents, one or more food grade acidulants, one or more food grade thickening agents, emulsifiers, natural flavors, or the like, or any combination thereof.

[0040] Examples of thickening agents include pectin, methylcellulose, guar gum, xanthan gum, arabic, konjac flour, rice flour, and locust bean gum. The food grade thickening agent may be added in an amount such that the resulting potassium chloride includes about 0.05 wt% to about 1 wt% food grade thickening agent.

[0041] Examples of food grade anticaking agents include calcium carbonate, magnesium carbonate, silicon dioxide, tricalcium phosphate, glycerin, and mineral oil. The food grade anticaking agent may be added in an amount such that the food grade potassium chloride includes about 0.1 wt% to about 1 wt% food grade anticaking agent. The food grade anticaking agent generally improves flow characteristics of the potassium chloride.

[0042] Examples of food grade acidulants include citric acid, malic acid, lactic acid, tartaric acid, fumaric acid, and acetic acid. The food grade acidulant may be added in an amount such that the potassium chloride includes about 0.05 wt% to about 1 wt% food grade acidulant. The resulting potassium chloride includes at least 98.0 wt% potassium chloride.

[0043] In 124, metallic impurities are removed from the potassium chloride. In one example, removing metallic impurities includes passing the potassium chloride through a metal detector, and removing any detected metal from the process stream.

[0044] In 126, the potassium chloride is analyzed by X-rays to check for foreign material prior to packaging, and any such detected foreign material is removed from the potassium chloride.

[0045] After the industrial grade potassium chloride has been treated according to process 100 to yield food grade potassium chloride, the food grade potassium chloride is packaged for transporting. In one example, the potassium chloride is packaged in bulk bags. In the absence of additives, the food grade potassium chloride is at least 99.0 wt% potassium chloride. If one or more additives have been added in 122, the food grade potassium chloride is least 98.0 wt% potassium chloride. The food grade potassium chloride has less than 5 ppm heavy metals. The food grade potassium chloride includes intact crystalline structures of the industrial grade potassium chloride. The particle size of the food grade potassium chloride is substantially the same as the particle size of the industrial grade potassium chloride (e.g., particles of various shapes generally having a largest dimension of up to 3 cm, up to 4 cm, or up to 8 cm).

[0046] In some embodiments, one or more operations in process 100 may be added, omitted, interchanged, or repeated. For example, one or more of operations 102, 104, 108, 110, 112, 114, 120, 122, 124, or 126 may be omitted. In certain embodiments, the order of one or more operations may be changed. In one example, operation 104 may occur before operation 102, such that the potassium chloride is optically screened before the fines are removed. In another example, operation 102, 104, or both may occur after operation 106, such that the potassium chloride is polished before it is optically screened, the fines are removed, or both. In certain cases, process 100 includes assessing one or more temperatures along the process stream (e.g., a temperature of the fluid, a temperature of the radiant heat at the heat source, a temperature of the potassium chloride during drying, and the like), a moisture content along the process stream (e.g., a moisture content of the potassium chloride before or after drying, before or after heating, or both), or both. In some cases, process 100 may include cooling the potassium chloride after heating in 112.

[0047] The process of preparing food grade potassium chloride from industrial grade potassium chloride described with respect to FIGS. 1A and IB may be implemented in a production line in which industrial grade potassium chloride is processed in a process stream to yield food grade potassium chloride as a product stream. The process may be a continuous flow process in which industrial grade potassium chloride is continuously provided as a feedstock to the production line and the food grade potassium chloride is continuously produced.

[0048] FIG. 2A depicts a first portion of an exemplary production line 200 for processing potassium chloride. Production line 200 includes bucket elevator 202, into which the industrial grade potassium chloride feedstock is provided. From bucket elevator 202, the potassium chloride advances to conveyor 204, from which the potassium chloride is delivered to fines screener 206. Fines screener 206 includes a screen or mesh 208 positioned at angle Θ with respect to vertical, such that fines in the feedstock fall through the screen or mesh into bin 210. Angle Θ may be in a range from 0° to 60° (e.g., a range from 15° to 60°, from 30° to 60°, or from 45° to 60°). Openings defined in the screen or mesh may have a minimum dimension of 0.1 cm, 0.3 cm, or 0.5 cm, such that the fines have a maximum dimension of up to 0.1 cm, 0.3 cm, or 0.5 cm, respectively, and the particles of potassium chloride that remain in the process stream have a minimum dimension of at least 0.1 cm, 0.3 cm, or 0.5 cm, respectively. Potassium chloride that remains in the process stream exits fines screener 206 through chute 212 and enters color optical screening system 214.

[0049] Optical screening system 214 includes camera 216 in conduit 218 and reject diverter 220 operatively coupled to the camera. Camera 216 may include, for example, a video graphic array (VGA) charge-coupled device (CCD) sensor (e.g., a Datalogic A30 Series camera with two Smart Vision lighting elements). Potassium chloride that enters optical screening system 214 is imaged with camera 216, and the images are analyzed to identify particles with color characteristics that fall outside a specified range. Particles with color characteristics that fall outside a specified range may be considered as impurities to be removed from the process stream. An integrated, high speed I/O allows fast rejection of the identified particles. The optical screening system may be controlled (e.g., by a controller) coupled to reject diverter 220, which is activated based on elapsed time such that the identified particles are removed from the process stream via chute 222 and collected in bin 210. Particles with color characteristics that fall inside the specified range do not trigger the reject diverter and pass through conduit 218 and into polishing system 224.

[0050] The potassium chloride is translated through polishing system 224 on conveyor 226. Conveyor 226 passes through chamber 228, in which the potassium chloride is polished via abrasion, agitation, contact with a fluid, or a combination thereof, as described with respect to FIG 1A. During the polishing process, the potassium chloride retains its crystalline form (i.e., is not completely dissolved). As such, processing the industrial grade potassium chloride via production line 200 does not include recrystallization of the potassium chloride.

[0051] In chamber 228, the potassium chloride may be contacted with or submerged in a polishing fluid. The polishing fluid, the potassium chloride, or both may be agitated to facilitate removal of impurities from the potassium chloride. The polishing fluid may be saturated with potassium chloride. In some cases, ultrasound system 230 with ultrasound transducers operatively coupled to chamber 228 cavitate the polishing fluid, thereby dislodging impurities from the potassium chloride as it moves through the chamber on conveyor 226. In one example, ultrasound system 230 includes three 1 kW ultrasound units (e.g., Hielscher Ultrasonics UlPl OOOhd). In some cases, polishing system 224 includes ozone system 232 fluidly coupled to chamber 228. Ozone system 232 provides ozone to chamber 228, thereby providing an antimicrobial effect and promoting disinfection and oxidation of contaminants. The potassium chloride typically has a dwell time of 5 seconds to 60 seconds (e.g., 10 seconds to 30 seconds or 15 seconds to 25 seconds) in chamber 228.

[0052] After exiting chamber 228, the potassium chloride is contacted with a finishing fluid from sprayers 234. The finishing fluid may be the same as or different from the polishing fluid. Finishing fluid from the sprayers 234 is filtered via filter 236 and pumped via pump 238 to reservoir 240. In one example, filter 236 is an automatic, self-cleaning filter (e.g., available from SANOVO). Fluid in reservoir 240 (e.g., a combination of polishing fluid and finishing fluid) may be recycled and provided to polishing system 224.

[0053] From polishing system 224, the potassium chloride is at least partially dried with dryers 242. Dryers 242 may include blowers, air knives, compressed gas, or a combination thereof, configured to contact the potassium chloride with a gas (e.g., air, an inert gas such as nitrogen, superheated steam, or the like). Dryers 242 remove moisture as well as loose matter from the potassium chloride. In one example, dryers 242 dry the potassium chloride as it ascends up elevator 244 toward heating system 246. In some cases, the potassium chloride undergoes UV treatment (e.g., on elevator 244) sufficient to achieve an antimicrobial effect as the potassium chloride moves from dryers 242 to heating system 246.

[0054] In heating system 246, potassium chloride on conveyor 248 is heated via radiant heat provided by one or more heaters 250. A dwell time of the potassium chloride under heaters 250 is typically at least 5 seconds, and may be over 5 minutes. In some cases, conveyor 248 is a wire mesh conveyor. In one example, heaters 250 are powered by natural gas and deliver about 300,000 BTU/hour. A temperature of the heaters may be at least 40°C, and a temperature of the potassium chloride on conveyor 248 may be at least 20°C (e.g., up to 250°C or higher). Heating the potassium chloride with heaters 250 removes residual moisture (e.g., to achieve less than 0.5 wt% or less than 0.2 wt% moisture), and may also provide an antimicrobial effect. In some cases, heating system 246 includes moisture sensor 252. Data from moisture sensor 252 may be used to adjust the dwell time (e.g., speed of conveyor 246) or amount of heat provided by heaters 250 to achieve a desired dryness of the potassium chloride. From heating system 246, the potassium chloride may receive a UV treatment to reduce or eliminate the presence of microbes before delivery to conveyor 254.

[0055] From conveyor 254, the potassium chloride is provided to a second portion of exemplary production line 200, depicted in FIG. 2B. As depicted in FIG 2B, the potassium chloride passes proximate or through magnet 256. In one example, magnet 256 is a rare earth magnet. Magnet 256 removes magnetic particles from the potassium chloride. After passing through magnet 256, the potassium chloride passes through cup feeder 258. From cup feeder 258, the potassium chloride enters mill 260. In one example, mill 260 is a hammer mill. In mill 260, the food grade potassium chloride is milled, thereby reducing the particle size of the potassium chloride. The potassium chloride is provided to rotary valve 262 and then to sifter 264. From sifter 264, fines are removed from the process stream to bin 266, and the potassium chloride is provided to hopper 268. Hopper 268 may be an eccentric hopper or a concentric hopper. From hopper 268, the potassium chloride enters elevator 270, and is provided to screw feeder 272. From screw feeder 272, the potassium chloride is provided to hopper 274. Hopper 274 may be an eccentric hopper or a concentric hopper. The potassium chloride from hopper 274 is provided to screw conveyor 276. From screw conveyor 276, the potassium chloride passes proximate or through magnet 278 for removing magnetic impurities from the potassium chloride. From magnet 278, the potassium chloride enters blender 280, in which the potassium chloride may be blended with one or more additives (e.g., an anticaking agent), as described above with respect to FIG IB.

[0056] From blender 280, the potassium chloride passes proximate or through a metal detector, and metallic impurities are removed from the process stream. After passing through the metal detector, the potassium chloride is typically analyzed by an X-ray unit to detect the presence of foreign material prior to packaging, and any foreign material is removed from the process stream. The resulting potassium chloride is packaged as food grade potassium chloride (e.g., in bulk for transporting).

[0057] Similar to process 100 described with respect to FIGS. 1 A and IB, one or more apparatuses, devices, or systems described with respect to FIGS. 2A and 2B may be omitted from production line 200 (e.g., magnet 256), or one or more apparatuses, devices, or systems may be added to the production line (e.g., one or more temperature sensors). In certain cases, the order of two or more apparatuses, devices, or systems in production line 200 may be changed or interchanged. In one example, fines screener 206 may be interchanged with optical screening system 214, such that the potassium chloride is optically screened before the fines are removed. In another example, fines screener 206, optical screening system 214, or both may be positioned after polishing system 224, such that the potassium chloride is polished before it is optically screened, the fines are removed, or both.

[0058] Referring again to FIG. 2A, operations in production line 200 may be controlled automatically or via a user interface. In some cases, a user may enter various control parameters via user interface 290 operatively coupled to one or more controllers 292. Controller(s) 292 have one or more processors 294 and memory unit(s) 296. Memory unit(s) 296 store instructions to control components of the production line (e.g., optical screening system 214, reject diverter 220, conveyors 204, 226, 248, 254, 276, and the like), and controller(s) 292 cooperate with various components of production line 200 (e.g., camera 216, reject diverter 220, conveyors 204, 226, 248, 254, 276, and the like) such that the system operates automatically, for example, to detect and reject contaminants in optical screening system 214.

Parameters (e.g., dwell time, temperatures, and the like) of production line 200 may be pre-selected or input by a user. In some cases, processor(s) 294 are operatively coupled to computer 298, such that production line 200 may be controlled remotely.

[0059] Implementations of the subject matter and the operations described in this specification can be implemented in digital electronic circuitry, or in computer software, firmware, or hardware, including the structures disclosed in this specification and their structural equivalents, or in combinations of one or more of them.

Implementations of the subject matter described in this specification can be implemented as one or more computer programs, i.e., one or more modules of computer program instructions, encoded on computer storage medium for execution by, or to control the operation of, data processing apparatus. Alternatively or in addition, the program instructions can be encoded on an artificially generated propagated signal, e.g., a machine-generated electrical, optical, or electromagnetic signal that is generated to encode information for transmission to suitable receiver apparatus for execution by a data processing apparatus. A computer storage medium can be, or be included in, a computer-readable storage device, a computer-readable storage substrate, a random or serial access memory array or device, or a combination of one or more of them. Moreover, while a computer storage medium is not a propagated signal, a computer storage medium can be a source or destination of computer program instructions encoded in an artificially generated propagated signal. The computer storage medium can also be, or be included in, one or more separate physical components or media (e.g., multiple CDs, disks, or other storage devices).

[0060] The operations described in this specification can be implemented as operations performed by a data processing apparatus on data stored on one or more computer-readable storage devices or received from other sources.

[0061] The term "data processing apparatus" encompasses all kinds of apparatus, devices, and machines for processing data, including by way of example a

programmable processor, a computer, a system on a chip, or multiple ones, or combinations, of the foregoing. The apparatus can include special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit). The apparatus can also include, in addition to hardware, code that creates an execution environment for the computer program in question, e.g., code that constitutes processor firmware, a protocol stack, a database management system, an operating system, a cross-platform runtime environment, a virtual machine, or a combination of one or more of them. The apparatus and execution environment can realize various different computing model infrastructures, such as web services, distributed computing and grid computing infrastructures.

[0062] A computer program (also known as a program, software, software application, script, or code) can be written in any form of programming language, including compiled or interpreted languages, declarative or procedural languages, and it can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but need not, correspond to a file in a file system. A program can be stored in a portion of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to the program in question, or in multiple coordinated files (e.g., files that store one or more modules, sub programs, or portions of code). A computer program can be deployed to be executed on one computer or on multiple computers that are located at one site or distributed across multiple sites and interconnected by a communication network.

[0063] The processes and logic flows described in this specification can be performed by one or more programmable processors executing one or more computer programs to perform actions by operating on input data and generating output. The processes and logic flows can also be performed by, and apparatus can also be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application specific integrated circuit).

[0064] Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read only memory or a random access memory or both. The essential elements of a computer are a processor for performing actions in accordance with instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, e.g., magnetic, magneto optical disks, or optical disks. However, a computer need not have such devices. Moreover, a computer can be embedded in another device, e.g., a mobile telephone, a personal digital assistant (PDA), a mobile audio or video player, a game console, a Global Positioning System (GPS) receiver, or a portable storage device (e.g., a universal serial bus (USB) flash drive), to name just a few. Devices suitable for storing computer program instructions and data include all forms of nonvolatile memory, media and memory devices, including by way of example semiconductor memory devices, e.g., EPROM, EEPROM, and flash memory devices; magnetic disks, e.g., internal hard disks or removable disks; magneto optical disks; and CD ROM and DVD-ROM disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry. [0065] To provide for interaction with a user, implementations of the subject matter described in this specification can be implemented on a computer having a display device, e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor, for displaying information to the user and a keyboard and a pointing device, e.g., a mouse or a trackball, by which the user can provide input to the computer. Other kinds of devices can be used to provide for interaction with a user as well; for example, feedback provided to the user can be any form of sensory feedback, e.g., visual feedback, auditory feedback, or tactile feedback; and input from the user can be received in any form, including acoustic, speech, or tactile input. In addition, a computer can interact with a user by sending documents to and receiving documents from a device that is used by the user; for example, by sending web pages to a web browser on a user's client device in response to requests received from the web browser.

[0066] Implementations of the subject matter described in this specification can be implemented in a computing system that includes a back end component, e.g., as a data server, or that includes a middleware component, e.g., an application server, or that includes a front end component, e.g., a client computer having a graphical user interface or a Web browser through which a user can interact with an implementation of the subject matter described in this specification, or any combination of one or more such back end, middleware, or front end components. The components of the system can be interconnected by any form or medium of digital data communication, e.g., a communication network. Examples of communication networks include a local area network ("LAN") and a wide area network ("WAN"), an inter-network (e.g., the Internet), and peer-to-peer networks (e.g., ad hoc peer to-peer networks).

[0067] The computing system can include clients and servers. A client and server are generally remote from each other and typically interact through a communication network. The relationship of client and server arises by virtue of computer programs running on the respective computers and having a client-server relationship to each other. In some implementations, a server transmits data (e.g., an HTML page) to a client device (e.g., for purposes of displaying data to and receiving user input from a user interacting with the client device). Data generated at the client device (e.g., a result of the user interaction) can be received from the client device at the server. [0068] Further modifications and alternative embodiments of various aspects will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be construed as illustrative only. It is to be understood that the forms shown and described herein are to be taken as examples of embodiments. Elements and materials may be substituted for those illustrated and described herein, parts and processes may be reversed, and certain features may be utilized independently, all as would be apparent to one skilled in the art after having the benefit of this description. Changes may be made in the elements described herein without departing from the spirit and scope as described in the following claims.