CN112225193B

CN112225193B - Production system, preparation method and components of toothpaste-grade sodium monofluorophosphate

Info

Publication number: CN112225193B
Application number: CN202011468598.9A
Authority: CN
Inventors: 刘如峰; 马明; 马小骥
Original assignee: Tianjin Changlong Junchi Technology Co ltd
Current assignee: Tianjin Changlong Junchi Technology Co ltd
Priority date: 2020-12-15
Filing date: 2020-12-15
Publication date: 2021-03-26
Anticipated expiration: 2040-12-15
Also published as: CN112225193A

Abstract

The sodium monofluorophosphate and the preparation method thereof can accurately control the content, free fluorine content and PH value of the sodium monofluorophosphate, and the prepared product has high purity and the method is easy to operate; the sodium monofluorophosphate production system provides technical support for the preparation method of the sodium monofluorophosphate, and specifically comprises a raw material mixing and blending device, a melting reaction furnace, a granularity regulating and controlling device, a transfer bin for transferring materials on a production line and a transfer bin lifter, wherein the feeding end of the raw material mixing and blending device is used for feeding sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide in different parts by weight and fully mixing the sodium hexametaphosphate, the sodium fluoride and the phosphorus pentoxide, the discharging end of the raw material mixing and blending device is communicated with the melting reaction furnace, and condensed sodium monofluorophosphate is screened out into qualified finished products through the granularity regulating and controlling device; the transfer bin hoister is used for lifting the transfer bin; the transfer bin is used for transferring and conveying materials among the devices.

Description

Production system, preparation method and components of toothpaste-grade sodium monofluorophosphate

Technical Field

The invention relates to the technical field of chemical production, in particular to a production system, a preparation method and components of toothpaste-grade sodium monofluorophosphate.

Background

Sodium Monofluorophosphate (MFP) is a fluorine-containing inorganic fine chemical with high added value, is an internationally recognized third-generation excellent toothpaste additive for preventing dental caries and desensitizing teeth, and can also be used as a preservative, a bactericide, a cosolvent, a cleaning agent for metal surface oxides, a corrosion inhibitor, fluorination of drinking water and the like.

At present, the preparation methods of sodium monofluorophosphate at home and abroad are mainly classified into a melting method, a liquid-phase neutralization method and a gas-phase fluorination method.

The melting method adopts sodium metaphosphate (or sodium metaphosphate, sodium polyphosphate and the like) and sodium fluoride as raw materials, and sodium monofluorophosphate is obtained by heating the raw materials in a reactor (generally, platinum, graphite, silver, platinum-rhodium alloy is selected as a lining) made of special materials to a melting state of 500-800 ℃ after pretreatment such as mixing and the like. The obtained product has high purity, the method process is simple, but the main raw material is sodium metaphosphate, and the moisture absorption is strong; the temperature required by the reaction is higher, the requirements on equipment materials are special, and the production energy consumption is high.

The liquid phase neutralization method uses phosphoric acid, hydrofluoric acid, sodium carbonate or sodium hydroxide as raw materials to carry out liquid phase neutralization. And evaporating, concentrating, crystallizing and drying the neutralized solution to obtain the sodium monofluorophosphate product. The method is characterized in that the raw materials are easy to obtain, the reaction is relatively mild, but the product can be obtained only by evaporation, concentration, crystallization and drying, and the reaction period is long. And the hydrofluoric acid has extremely strong corrosivity, so the hydrofluoric acid has special requirements on equipment materials and structures, the investment on production devices is high, the production process is difficult to control, and the purity of the prepared product is low.

The gas phase fluorination method comprises the steps of drying solid sodium pyrophosphate or disodium hydrogen phosphate, placing the dried solid sodium pyrophosphate or disodium hydrogen phosphate into a reaction container, controlling the temperature to be 200-450 ℃ for heating, and then passing through hydrogen fluoride gas flow. The solid raw material sodium polyphosphate and anhydrous hydrogen fluoride flow are subjected to fluorination reaction to prepare the sodium monofluorophosphate. The method is simple and has mild reaction conditions. However, the fluorine yield is low, and hydrogen fluoride gas exists after the reaction, so that the treatment is difficult, and the production cost is high. If the hydrogen fluoride is aerated for a long time, side reaction of sodium monofluorophosphate and hydrogen fluoride can be caused, and the purity of the product is greatly influenced.

Among the three production technologies of sodium monofluorophosphate, the melting method is the most traditional at present, and a liquid-phase neutralization method and a gas-phase fluorination method are developed later, and the main purposes are to reduce the reaction temperature and widen the range of available raw materials. But the melting method has the advantages of simple method, high product purity and the like, and can meet the requirement that the purity is more than or equal to 95 percent in the national standard GB24567-2009 sodium monofluorophosphate for toothpaste industry. At present, the method is still the first choice for industrially producing sodium monofluorophosphate.

Through published patent searches, the following comparison documents were found:

a system and a method for preparing sodium monofluorophosphate for toothpaste (CN110697675A) disclose a system and a method for preparing sodium monofluorophosphate for toothpaste. The system comprises a reaction furnace, a product treatment device and a flue gas treatment device; the product treatment device comprises a crushing device, a screening device, a separation device and a sterilization device which are connected in sequence; the flue gas treatment device comprises a dust collecting device, a dust removing device and a gas purifying device which are connected in sequence. Adding a reaction substrate into a reaction furnace for reaction, introducing the generated product into a product treatment device for crushing, screening, separating, sterilizing and disinfecting; and introducing the flue gas generated by the reaction of the reaction furnace into a flue gas treatment device for treatment and then discharging. The system and the method solve the problems that sodium monofluorophosphate produced by the prior art is not sterilized and disinfected, has colored and harmful impurities, and generates smoke dust and harmful waste gas. The produced product not only meets the HACCP standard, but also reaches the microbial inspection standard of an inlet food-grade product, and can effectively remove dust and waste gas.

Through analysis, the component proportion, the production method and the production equipment in the patent are all different from the application, so the novelty of the application is not influenced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a production system, a preparation method and components of toothpaste-grade sodium monofluorophosphate, wherein the sodium monofluorophosphate and the preparation method thereof can accurately control the content, the free fluorine content and the pH value of the sodium monofluorophosphate, and the prepared product has high purity and the method is easy to operate; the sodium monofluorophosphate production system of the invention provides technical support for the preparation method of the sodium monofluorophosphate.

A production system of sodium monofluorophosphate comprises a raw material mixing and blending device, a melting reaction furnace, a cooler, a crusher, a granularity regulating and controlling device, a packer, a transfer bin for transferring materials on a production line and a transfer bin lifter, wherein the feed end of the raw material mixing and blending device is used for putting different weight parts of sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide and fully mixing the sodium hexametaphosphate, the discharge end of the raw material mixing and blending device is communicated with the melting reaction furnace, liquid sodium monofluorophosphate after melting reaction is introduced into the cooler for cooling and fixedly connecting, then is introduced into the crusher for crushing, finally sodium monofluorophosphate with qualified granularity is screened out by the granularity regulating and controlling device, and finally finished sodium monofluorophosphate is introduced into the packer for packing; the transfer bin hoister is arranged between the melting reaction furnace and the crusher and used for lifting the transfer bin and supplying materials to the crusher; the transfer bin is used for transferring and conveying materials among the raw material mixing and blending device, the melting reaction furnace, the cooler, the pulverizer, the granularity regulating and controlling device and the packaging machine.

The raw material mixing and blending device comprises a mixing tank, wherein the middle part of the mixing tank is coaxially connected with a stirring unit in a penetrating manner, a plurality of slope-shaped feed inlets are radially formed in the upper part of the mixing tank, a plurality of spiral feeders extending into the slope-shaped feed inlets are fixedly arranged on the upper part of the mixing tank, and a spiral feeder extending into the mixing tank is fixedly arranged on the lower part of the mixing tank along the horizontal direction; the stirring unit comprises a first motor, a first shaft lever, an outer stirring ring, a second motor, a second shaft lever and an inner stirring ring, wherein the first motor is coaxially and fixedly arranged at the top of the material mixing tank, the first shaft lever extending downwards into the material mixing tank is coaxially and fixedly arranged at the output end of the first motor, and the outer stirring ring is coaxially and fixedly arranged on the first shaft lever; the second motor is fixedly arranged below the material mixing tank and is in power connection with the power input end of the second shaft lever through a driving belt; the second shaft rod extends upwards into the mixing tank, the top of the second shaft rod is coaxially and rotatably connected with the bottom end of the first shaft rod through a shaft seat, and an inner stirring ring is coaxially and fixedly arranged on the second shaft rod; the bottom of the outer stirring ring is connected with the second shaft rod in a rotating fit mode, and the top of the inner stirring ring is connected with the first shaft rod in a rotating fit mode.

The outer stirring ring and the inner stirring ring respectively comprise a fixed support ring, a rotating support ring and V-shaped stirring blades, wherein the opening ends of the V-shaped stirring blades are arranged towards the axle center of the mixing tank, one ends of the V-shaped stirring blades are fixedly connected with the fixed support ring, and the other ends of the V-shaped stirring blades are fixedly connected with the rotating support ring; a fixed support ring of the outer stirring ring is coaxially and fixedly arranged with the first shaft rod, and a rotary support ring of the outer stirring ring is rotatably sleeved on the outer wall of the second shaft rod through a bearing; the fixed support ring of the inner stirring ring is coaxially and fixedly installed with the second shaft rod, and the rotary support ring of the inner stirring ring is rotatably sleeved on the outer wall of the first shaft rod through a bearing.

And the inner wall of the end surface of the slope feeding hole is a slope surface which inclines downwards towards the axis direction of the mixing tank, the slope surface is in rotating fit with a rotating shaft of the spiral feeder, and the spiral feeder fills raw materials into the mixing tank through the slope feeding hole.

The melting reaction furnace comprises a reaction furnace barrel, wherein an insulating bottom support with a discharge hole is axially packaged at the lower part of the reaction furnace barrel, an insulating top cover with a feed hole is axially packaged at the upper part of the reaction furnace barrel, and a coil heating layer, a quartz sand heat-insulating layer, a ceramic sleeve and a graphite furnace core are coaxially sleeved in sequence in the middle of the reaction furnace barrel; the top of the graphite furnace core is communicated with the feeding hole, the bottom of the graphite furnace core is communicated with the discharging hole, and the graphite furnace core comprises a graphite furnace disc, a graphite reaction cylinder and a liquid drainage unit; the top of the graphite reaction cylinder is coaxially and fixedly connected with a graphite furnace plate, and the bottom of the graphite reaction cylinder is fixedly inserted with a liquid discharge unit communicated with the discharge hole.

The liquid discharge unit comprises a graphite column and a liquid collection box, wherein the circumferential outer wall of the graphite column is in clearance fit connection with the circumferential inner wall of the graphite reaction cylinder, a plurality of spiral liquid discharge grooves communicated with the top surface and the bottom surface of the graphite column are formed in the circumferential outer wall of the graphite column, and the bottom of the graphite column is fixedly connected with the liquid collection box in a sealing manner; the top surface of the liquid collecting box is provided with a plurality of liquid discharging holes communicated with the spiral liquid discharging groove, the side wall of the liquid collecting box is sealed by the ceramic sleeve and is fixedly supported, and the bottom of the liquid collecting box is communicated with the discharging hole.

The bottom surface of the insulating top cover is insulated, sealed, fixed and pressed on the coil heating layer and the top surface of the quartz sand heat-insulating layer, a ceramic sleeve is fixedly inserted on the bottom surface of the insulating top cover, and a graphite reaction cylinder is fixedly penetrated in a discharge port of the insulating top cover; the graphite furnace plate is coaxially and fixedly arranged at the opening at the top of the graphite reaction cylinder, and the bottom surface of the graphite furnace plate is fixedly lapped on the top surface of the insulating top cover.

And a plurality of thermocouple sheaths for penetrating and installing thermocouples are fixedly installed on the reaction furnace cylinder in a radial penetrating manner, one end of each thermocouple sheath radially penetrates through the coil heating layer, the quartz sand heat-insulating layer and the ceramic sleeve and is attached to the circumferential outer wall of the graphite furnace core, and the other end of each thermocouple sheath extends towards the outside of the reaction furnace cylinder.

The particle size regulating device comprises a cylindrical barrel, a conical screen and a grinding and screening unit, wherein the top and the bottom of the cylindrical barrel are sealed, the conical screen with a large diameter end arranged upwards is coaxially and fixedly arranged in the middle of the cylindrical barrel, a motor for providing rotary power for the grinding and screening unit is arranged at the bottom of the conical barrel, and a feeding port communicated with the interior of the conical screen is fixedly arranged at the top of the conical barrel; the conical screen divides the interior of the conical cylinder into a plurality of material screening areas, and the material screening areas comprise a grinding area in the conical screen, a fine material area at a crack between the conical screen and the inner wall of the cylindrical cylinder and a coarse material area at the bottom of the conical screen; the outer wall of the cylindrical barrel is fixedly provided with a plurality of fans which are respectively communicated with the coarse material area and the fine material area, and the outer wall of the cylindrical barrel is provided with a plurality of discharge holes which are respectively communicated with the coarse material area and the fine material area.

Moreover, a sealing plate for sealing the opening at the top of the cylindrical barrel is coaxially and fixedly arranged at the top of the conical screen, and a plurality of layers of grinding plates are coaxially and fixedly arranged in the conical screen; the periphery of the grinding plate is fixedly supported with a conical screen, the edge of the grinding plate is provided with feed openings which are communicated along the gravity direction, and the feed openings on the adjacent grinding plates are arranged in a staggered manner.

And the feed opening on the grinding plate at the lowermost layer of the conical screen is communicated with the coarse material area.

The grinding and screening unit comprises a rotating shaft, a rotating blade plate and a grinding roller, wherein the top end of the rotating shaft is rotatably connected with a cross beam at the top of the cylindrical barrel, the middle part of the rotating shaft downwards coaxially penetrates through the sealing plate, the plurality of grinding plates and the coarse material area in sequence, the bottom of the rotating shaft is rotatably connected with the bottom plate of the cylindrical barrel, the lower part of the rotating shaft is in power connection with the output end of the motor through a transmission belt, and the rotating shaft positioned in the conical barrel is sleeved with the plurality of rotating blade plates; the bottom of the rotating blade plate is rotatably connected with a plurality of grinding rollers, and the grinding rollers are matched with the top surface of the grinding plate to grind materials.

And the rotating vane plate is axisymmetric and fixedly sleeved on the rotating shaft, and two ends of the rotating vane plate are provided with ejection slopes matched with the gradient of the section of the conical screen.

Moreover, the transfer bin comprises a hopper and a wheel carrier movably connected with the hopper; the two sides of the top of the wheel carrier are fixedly provided with hanging lugs extending downwards, the side wall of the middle part of the wheel carrier is provided with a buffer supporting unit arranged along the horizontal direction, and the bottom of the wheel carrier is fixedly provided with a thumb wheel motor; swing shafts which penetrate through and are rotatably connected to the hanging lugs are symmetrically and fixedly arranged on two sides of the upper part of the hopper, an impact cushion plate of an impact buffering supporting unit is fixedly arranged on the side wall of the middle part of the hopper, and a deflector rod which extends along the horizontal direction is fixedly arranged on the side wall of the bottom of the hopper; the output end of the shifting wheel motor is coaxially and fixedly provided with a shifting wheel, and the circumferential outer wall of the shifting wheel is connected with the circumferential outer wall of the shifting rod in a sliding fit manner.

The buffer support unit comprises a support beam, a support plate, a buffer spring and an impact plate, wherein the support beam is fixedly arranged on the wheel frame along the horizontal direction, and the support plate is fixedly connected to the side wall of the support beam facing the interior of the wheel frame; the middle part of the supporting plate is fixedly connected with a buffer spring along the horizontal direction, and the free end of the buffer spring is fixedly connected with an impact plate; the impact plate is compositely bonded with a rubber pad.

Furthermore, one side of the impact pad plate is made into a conical cambered surface, and the other side is made into an impact plane of the impact rubber pad.

And one side of the top of the wheel carrier is fixedly connected with a push rod which horizontally extends to the outside of the wheel carrier, the push rod is movably sleeved with a hook, and the push rod is connected with a positioning pin for positioning the hook in a penetrating way.

The transfer bin elevator comprises a frame, wherein one side of the frame is a feeding side, and the other side of the frame is a discharging side; the elevator also comprises a front shaft chain, a rear shaft chain and a plurality of chain plates, wherein the two side walls in the rack are symmetrically and rotatably connected with the rear shaft chain, and the middle part of the rack is symmetrically and rotatably connected with the front shaft chain; front connecting frames are symmetrically and fixedly connected to the bottom surfaces of the two sides of the front end of the chain plate in the conveying direction, and rear connecting frames are symmetrically and fixedly connected to the bottom surface of the middle part of the rear end of the chain plate in the conveying direction; the front connecting frame is rotationally connected with a front shaft chain, and the front shaft chain is hung on the bottom of the rack and the side wall of the discharge side of the rack in an L shape; the rear axle roller is rotationally connected with a rear axle chain, and the rear axle chain is hung on the rack in a square shape; a plurality of limiting plates are fixedly arranged on the chain plate, and the plurality of limiting plates jointly enclose a lifting limiting area of the transfer bin.

The bottom of the feeding side of the frame, the bottom of the discharging side of the frame and the top of the discharging side of the frame are respectively and rotatably connected with a through shaft, and the two side walls of the frame are respectively and symmetrically connected with a front chain supporting wheel, a front chain tensioning wheel, a rear chain tensioning wheel and a rear chain jacking wheel in a rotating manner; the two ends of the through shaft are symmetrically and coaxially fixedly connected with a rear chain driving wheel, and the middle part of the through shaft is symmetrically and coaxially fixedly connected with a front chain driving wheel.

And the front shaft chain is respectively wound on the front chain driving wheels at the two ends of the through shaft, the middle corner of the front shaft chain rotates and supports against the front chain tension wheel, and the front chain tension wheel is connected with the front shaft chain, and the front chain support wheel is rotatably supported at the lower part of the front shaft chain.

And the rear shaft chain is respectively wound on a rear chain driving wheel in the middle of the through shaft and a rear chain jacking wheel on the upper part of the feeding side of the rack, and the rear shaft chain rotates on the outer wall close to the feeding side of the rack and supports the rear chain tensioning wheel in a jacking mode.

And one end of the through shaft is connected with a motor.

The chain plate comprises a plurality of laths which are arranged in parallel and are hinged in sequence; the front shaft roller is oppositely and fixedly arranged on the bottom surface of a first batten at the front end of the chain plate in the conveying direction; the rear shaft roller is fixedly arranged on the bottom surface of the first batten at the rear end in the conveying direction of the chain plate in a back-to-back mode; and a limiting plate protruding upwards is fixedly arranged on the lath in the middle of the chain plate.

A method for preparing sodium monofluorophosphate by using a sodium monofluorophosphate production system comprises the following steps:

the method comprises the following steps: a material mixing procedure, namely firstly weighing sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide materials according to a feeding proportion, and then feeding the materials by using a raw material mixing and blending device; after the feeding is finished, starting to mix by using a raw material mixing and blending device, and discharging from a discharge hole at the bottom of the mixer after the mixing time reaches 30 min;

step two: a synthesis procedure, namely transferring the mixed materials to a feeding port above the melting reaction furnace through a transfer bin and a transfer bin elevator, and starting to feed materials into the melting reaction furnace when the temperature of the melting reaction furnace reaches 400 ℃; adjusting the feeding speed according to the reaction and discharge speeds of the melting reaction furnace, and always keeping the materials in the melting reaction furnace; the reaction temperature is 400-800 ℃; when the materials react in the melting reaction furnace for a certain time, molten sodium monofluorophosphate is generated and flows out of a discharge hole of the melting reaction furnace; a cooler is arranged below the melting reaction furnace to ensure that the molten sodium monofluorophosphate is cooled into a solid semi-finished product; collecting the solid semi-finished product into a transfer bin; each raw material mixing and blending device, the melting reaction furnace and the cooler are a set of reaction device, and the yield of each set of reaction device can reach 50 kg/h;

step three: a crushing step, namely transferring the solid sodium monofluorophosphate semi-finished product output from the synthesis step to crushing equipment through a transfer bin, crushing the semi-finished product through the crushing equipment, screening the granularity through a granularity regulating and controlling device, and storing the qualified granularity product in the transfer bin;

step four: a packaging procedure, wherein the materials in the semi-finished product bins are conveyed to a mixer to be subjected to total mixing of the materials in the same batch, the mixing time is 15min, and discharging is started; weighing the materials by a packaging machine, receiving the materials, feeding the materials into a packaging bag, conveying the materials to a heat sealing machine, and carrying out heat sealing on the packaging bag made of the double-layer polyethylene material; after the heat seal is finished, conveying the fabric to a sack closer to sew the kraft bags; and after the packaging bags are sewn, rechecking the weight through a rechecking scale, and stacking and warehousing after the packaging bags are qualified.

The synthesis process of step two includes a plurality of reactions that are performed simultaneously, and the reaction equation is as follows:

wherein the reaction of sodium hexametaphosphate and sodium fluoride is the main reaction:

because the raw material and the air contain a certain amount of moisture, the following side reactions occur:

finally, phosphorus pentoxide is added for impurity removal reaction, and the by-product in the side reaction is promoted to be converted into sodium monofluorophosphate:

the sodium component of monofluorophosphate prepared by a sodium monofluorophosphate production system comprises the following raw materials in parts by weight: 800 portions of sodium hexametaphosphate; 600 portions of sodium fluoride 300-; 30-70 parts of phosphorus pentoxide.

The invention has the advantages and technical effects that:

according to the raw material mixing and blending device in the production system of the toothpaste grade sodium monofluorophosphate, a plurality of slope-shaped feed inlets at the top of the mixing tank are connected for conveying different raw materials, the feed speeds of the raw materials with different components are independently controlled through a plurality of spiral feeders, and the upper and lower sections in the mixing tank are separately stirred through the stirring unit, so that the raw materials in the mixing tank are fully mixed, and the phenomenon that the quality of the sodium monofluorophosphate is influenced due to the accumulation of single-component raw materials in the tank is avoided. The first motor, the first shaft lever and the outer stirring ring of the stirring unit are used for forward/reverse stirring at the position, far away from the axis, inside the mixing tank, and the second motor, the second shaft lever and the inner stirring ring are used for forward/reverse stirring at the position, near the axis, inside the mixing tank. Set up the inside of domatic feed inlet intercommunication screw mixer and compounding jar through compounding jar inner chamber top, wherein domatic and screw mixer's the pivot normal running fit of domatic feed inlet is connected, provides the pivot and supports and avoid the obstructed function of powdery material at screw mixer discharge end.

According to the melting reaction furnace in the production system of the toothpaste grade sodium monofluorophosphate, the main body heat insulation support is provided for the melting reaction furnace through the reaction furnace barrel, the insulation base and the insulation top cover; the coil heating layer in the reaction furnace cylinder is used for providing radiant heat energy for the graphite furnace core; the quartz sand heat-insulating layer is used for isolating heat conduction between the graphite furnace core and the reaction furnace barrel; the ceramic sleeve is used for providing a guide support for the graphite furnace core and has good heat resistance, so that the ceramic sleeve is not burnt and melted by the graphite furnace core at high temperature; the communicating feed inlet at the top of the graphite core is used for feeding powdery mixed raw materials, the graphite column at the bottom of the graphite furnace core is used for prolonging the detention time of the mixed materials in the graphite furnace core and realizing powder/liquid separation, and finally, the molten sodium monofluorophosphate is collected by the liquid collecting box and is discharged by the discharge outlet. Can realize continuous production from powder mixed raw materials to molten sodium monofluorophosphate, and is particularly suitable for continuous production and use on a sodium monofluorophosphate production line.

The invention provides a granularity regulating device in a production system of toothpaste grade sodium monofluorophosphate, which provides main body support through a cylindrical barrel, screens materials with qualified granularity by a conical screen mesh, temporarily stores and removes the materials with the qualified granularity by a fine material area, temporarily stores and removes waste materials with unqualified granularity by a coarse material area, feeds the materials into the conical screen mesh through a feed port, provides rotary power for a grinding and screening unit by a motor, finally stirs the materials by a rotary blade plate of the grinding and screening unit, radially extrudes the materials to the conical screen mesh through an ejection slope surface, grinds large-particle materials by matching a grinding roller and a grinding plate, realizes multilayer grinding and screening of the sodium monofluorophosphate particles through a plurality of layers of grinding plates and feed ports staggered on adjacent grinding plates, prolongs the residence time of the large sodium monofluorophosphate particles in the conical screen mesh, and fully grinds and crushes the large sodium monofluorophosphate particles. But the large granule material among this granularity regulation and control device quickly separating sodium monofluorophosphate powder to can carry out the multistage grinding to the large granule material and handle, need not to send the large granule material of sieving out back the breaker and do over again, effectively improved half-finished granularity inspection efficiency of sodium monofluorophosphate.

According to the transfer bin in the production system of the toothpaste grade sodium monofluorophosphate, the hopper is transferred through the wheel carrier, the hanging lugs on the wheel carrier are used for movably hanging the hopper, the push rod at the top of the wheel carrier is convenient for workers to push the transfer bin, and the hanging hooks and the positioning pins on the push rod are used for hanging and fixing the transfer bin in the processing waiting area, so that the uncontrollable displacement of the wheel carrier caused by impact and vibration when the wheel carrier is unattended is avoided; the impact buffer support at the swinging limit position of the hopper is carried out through the support beam, the support plate, the buffer spring, the impact plate and the rubber pad in the middle of the wheel carrier and the impact base plate in the middle of the hopper, so as to provide impact vibration force for the side wall of the hopper, further break up sodium monofluorophosphate powder in the hopper and avoid caking in the standing and drying process; and finally, a driving lever at the bottom of the hopper, a driving wheel and a driving wheel motor at the bottom of the wheel carrier provide power for swinging of the hopper, so that dynamic temporary storage of the sodium monofluorophosphate powder in the transfer process is realized. This transfer feed bin can guarantee to transport and the in-process of keeping in, and the sodium monofluorophosphate powder in the hopper is in the motion state that the vibrations striking leads to all the time, avoids having the sodium monofluorophosphate powder caking of moisture, can effectively reduce the rejection rate in the follow-up total mixed machining process in batches, is particularly useful for the sodium monofluorophosphate of the total mixed machining in batches to keep in the transportation operation.

The invention relates to a transfer bin elevator in a production system of toothpaste grade sodium monofluorophosphate, which is characterized in that a main body support is provided by a rack, a chain plate performs a circularly reciprocating horizontal lifting action of a transfer bin, the chain plate is supported by a front shaft chain and a rear shaft chain together, and guide supports are respectively provided for a front connecting frame at the front end of the chain plate and a rear connecting frame at the rear end of the chain plate, and the elevator specifically comprises: one end of the through shaft is connected with a motor to provide rotary power for the through shaft, the rear chain driving wheel and the front chain driving wheel so as to respectively drive the front shaft chain and the rear shaft chain to be conveyed and operated on the rack; the front chain driving wheel provides L-shaped positioning support for the front shaft chain, the front chain tensioning wheel provides chain tensioning force for the front shaft chain, and the front chain supporting wheel provides bottom supporting force for the chain plate, so that when the transfer bin initially runs into the chain plate, the horizontal support of the chain plate is ensured; furthermore, the rear chain driving wheel provides positioning support for three corners in the shape of a Chinese character 'kou' for the rear shaft chain, the rear chain jacking wheel is used for providing positioning support for the other corner in the shape of the Chinese character 'kou' of the rear shaft chain, and the rear chain tensioning wheel is used for providing chain tensioning force for the rear shaft chain; and the laths of the last chain plate are fixedly provided with limiting plates, and a plurality of limiting plates surround to form a lifting limiting area, so that the bottom of a transfer bin in the lifting process is limited, and the transfer bin is prevented from sliding down from the chain plate. This transfer feed bin lifting machine can circulate reciprocal and continuous lifting operation for the transfer feed bin of lifting and transporting sodium monofluorophosphate has improved the smoothness nature of sodium monofluorophosphate streamlined production, avoids the feed bin transfer time overlength and the pipelining production pause problem that leads to.

The preparation method and the components of the toothpaste grade sodium monofluorophosphate can accurately control the content, the free fluorine content and the pH value of the sodium monofluorophosphate, the prepared product has high purity and the method is easy to operate, and the raw material sodium hexametaphosphate meets the technical requirements in GB 1886.4-2015 food additive sodium hexametaphosphate; the raw material sodium fluoride meets the technical requirements in HG/T5210-2017; the raw material phosphorus pentoxide should meet the technical requirements of analyzing pure phosphorus pentoxide in GB/T2305-2000. The indexes such as impurity content, PH value and the like are controlled from the raw materials, so that the sodium monofluorophosphate prepared from the raw materials with the technical requirements can meet the technical indexes of the national standard GB24567-2009 sodium monofluorophosphate for toothpaste industry.

Description of the drawings:

FIG. 1 is a schematic diagram of the connection of a sodium monofluorophosphate production system according to the present invention;

FIG. 2 is a half sectional view of the mixing and blending apparatus for raw materials in the present invention;

FIG. 3 is a top view of the outer stirring ring of the material mixing and blending apparatus of the present invention;

FIG. 4 is a bottom view of the outer stirring ring of the raw material mixing and blending apparatus of the present invention;

FIG. 5 is a half sectional view of a melting reactor of the present invention;

FIG. 6 is a schematic perspective view of a graphite column of the melting reactor of the present invention;

FIG. 7 is a plan view of a liquid collecting box of the melting reaction furnace of the present invention;

FIG. 8 is a sectional view showing a connection structure of a graphite column and a liquid collecting box of the melting reactor of the present invention;

FIG. 9 is a half sectional view of a particle size controlling apparatus according to the present invention;

FIG. 10 is a top view of a particle size controlling apparatus according to the present invention;

FIG. 11 is a top view of a conical screen of a particle size controlling apparatus according to the present invention;

FIG. 12 is a front view of the transfer bin of the present invention;

FIG. 13 is a side view of a transfer bin of the present invention;

FIG. 14 is a schematic top view of a portion of an impact pad and cushioning support unit of the transfer bin of the present invention;

fig. 15 is a half sectional view of the transfer bin elevator of the present invention;

FIG. 16 is a schematic view showing the connection between the link plate and the front axle chain of the transfer bin elevator of the present invention as it descends to the lowest position;

FIG. 17 is a schematic view showing the connection between the link plate of the transfer bin elevator and the rear axle chain when the link plate descends to the lowest position in the present invention;

FIG. 18 is a schematic view showing the connection between the link plate of the transfer bin elevator and the front axle chain when the link plate moves upward to the highest position in the present invention;

FIG. 19 is a schematic view showing the connection between the chain plate of the transfer bin elevator and the rear axle chain when the chain plate moves upward to the highest position;

FIG. 20 is a schematic view showing the connection between the link plate and the front axle chain of the transfer bin elevator of the present invention as it descends to an intermediate position;

FIG. 21 is a schematic view showing the connection between a link plate of the transfer bin elevator and a rear axle link when the link plate descends to an intermediate position in the present invention;

FIG. 22 is a top view of the link plate, the front axle chain and the rear axle chain of the transfer bin elevator of the present invention;

FIG. 23 is a partial side view of a flight of the transfer bin lift of the present invention;

in the figure: 1-raw material mixing and blending device; 11-a screw feeder; 12-a slope feeding hole; 13-a first electric machine; 14-slope surface; 15-a first shaft; 16-outer stirring ring; 17-shaft seat; 18-inner stirring ring; 19-a second electric machine; 110-a conveyor belt; 111-a second shaft; 112-a bearing; 113-rotating support ring; 114-a stationary support ring; 115-mixing tank; 116-V shaped stirring blades;

2-a melting reaction furnace; 21-a reaction furnace cylinder body; 22-an insulating top cover; 23-graphite oven plates; 24-a feed port; 25-a coil heating layer; 26-quartz sand heat-insulating layer; 27-a ceramic sleeve; 28-graphite reaction cylinder; 29-graphite columns; 210-a thermocouple sheath; 211-liquid collecting box; 212-insulating shoe; 213-a discharge hole; 214-drain hole; 215-spiral drainage groove;

3-transferring the stock bin elevator; 31-a frame; 32-rear axle chain; 33-front axle chain; 34-a chain plate; 35-a limiting plate; 36-rear chain jacking wheels; 37-through shaft; 38-front chain tensioner; 39-front chain support wheels; 310-front chain drive wheel; 311-rear chain tensioner; 312-rear chain drive wheel; 313-front link frame; 314-rear link; 315-slats; 316-a lift limiting zone;

4-transferring the feed bin; 41-wheel carrier; 42-a hopper; 43-a pendulum shaft; 44-hanging ears; 45-impact pad; 46-a rubber pad; 47-a strike plate; 48-a buffer spring; 49-support plate; 410-a support beam; 411-thumb wheel; 412-a thumb wheel motor; 413-a driving lever; 414-hook; 415-a locating pin; 416-a push rod; 417 — plane of impact; 418-conical cambered surface;

5-a particle size regulating device; 51-cylindrical barrel; 52-a cross beam; 53-closing plate; 54-a rotating shaft; 55-a feeding port; 56-rotating the blade; 57-conical screens; 58-a feed opening; 59-ejecting slope surface; 510-grinding rollers; 511-grinding plate; 512-coarse material area; 513-a motor; 514-discharge port; 515-a drive belt; 516-a fan; 517-fine material area;

6-a pulverizer.

The specific implementation mode is as follows:

for a further understanding of the contents, features and effects of the present invention, reference will now be made to the following examples, which are to be considered in conjunction with the accompanying drawings. It should be noted that the present embodiment is illustrative, not restrictive, and the scope of the invention should not be limited thereby.

A production system of sodium monofluorophosphate, the production system includes mixing and allocating apparatus 1 of raw materials, melting reaction furnace 2, cooler, comminutor, graininess regulates and controls apparatus 5, packaging machine, and is used for the transfer stock bin 4 and transfer stock bin elevator 3 of the material transfer on the production line, wherein the feed end of mixing and allocating apparatus of raw materials is used for throwing in sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide of different weight share and fully mixing the three, the discharge end of the mixing and allocating apparatus of raw materials communicates the melting reaction furnace, the liquid sodium monofluorophosphate is introduced into the cooler to cool and fix after the melt reaction, then introduce into the comminutor and pulverize, screen the qualified sodium monofluorophosphate of graininess through the graininess regulates and controls apparatus finally, finished product sodium monofluorophosphate is introduced into the packaging machine and packed; the transfer bin hoister is arranged between the melting reaction furnace and the crusher and used for lifting the transfer bin and supplying materials to the crusher; the transfer bin is used for transferring and conveying materials among the raw material mixing and blending device, the melting reaction furnace, the cooler, the pulverizer, the granularity regulating and controlling device and the packaging machine.

Moreover, the raw material mixing and blending device comprises a material mixing tank 115, the middle part of the material mixing tank is coaxially connected with a stirring unit in a penetrating manner, a plurality of slope-shaped feed inlets 12 are radially formed in the upper part of the material mixing tank, a plurality of spiral feeders 11 extending into the slope-shaped feed inlets are fixedly arranged on the upper part of the material mixing tank, and a spiral feeder extending into the material mixing tank is fixedly arranged on the lower part of the material mixing tank along the horizontal direction; the stirring unit comprises a first motor 13, a first shaft lever 15, an outer stirring ring 16, a second motor 19, a second shaft lever 111 and an inner stirring ring 18, wherein the first motor is coaxially and fixedly arranged at the top of the mixing tank, the first shaft lever extending downwards into the mixing tank is coaxially and fixedly arranged at the output end of the first motor, and the outer stirring ring is coaxially and fixedly arranged on the first shaft lever; the second motor is fixedly arranged below the mixing tank and is in power connection with the power input end of the second shaft lever through a transmission belt 110; the second shaft lever extends upwards into the mixing tank, the top of the second shaft lever is coaxially and rotatably connected with the bottom end of the first shaft lever through a shaft seat 17, and an inner stirring ring is coaxially and fixedly arranged on the second shaft lever; the bottom of the outer stirring ring is connected with the second shaft rod in a rotating fit mode, and the top of the inner stirring ring is connected with the first shaft rod in a rotating fit mode.

The outer stirring ring and the inner stirring ring respectively comprise a fixed support ring 114, a rotating support ring 113 and a V-shaped stirring blade 116, wherein the opening end of the V-shaped stirring blade is arranged towards the axle center of the mixing tank, one end of the V-shaped stirring blade is fixedly connected with the fixed support ring, and the other end of the V-shaped stirring blade is fixedly connected with the rotating support ring; a fixed support ring of the outer stirring ring is coaxially and fixedly arranged with the first shaft rod, and a rotary support ring of the outer stirring ring is rotatably sleeved on the outer wall of the second shaft rod through a bearing 112; the fixed support ring of the inner stirring ring is coaxially and fixedly installed with the second shaft rod, and the rotary support ring of the inner stirring ring is rotatably sleeved on the outer wall of the first shaft rod through a bearing.

And the inner wall of the end surface of the slope feeding hole is made into a slope 14 which inclines downwards towards the axis direction of the mixing tank, the slope is connected with a rotating shaft of the spiral feeder in a rotating fit manner, and the spiral feeder fills raw materials into the mixing tank through the slope feeding hole.

Moreover, the melting reaction furnace comprises a reaction furnace cylinder 21, the lower part of the reaction furnace cylinder is axially packaged with an insulating bottom support 212 with a discharge hole 213, the upper part of the reaction furnace cylinder is axially packaged with an insulating top cover 22 with a feed hole 24, and the middle part of the reaction furnace cylinder is sequentially coaxially sleeved with a coil heating layer 25, a quartz sand heat-insulating layer 26, a ceramic sleeve 27 and a graphite furnace core; the top of the graphite furnace core is communicated with the feeding hole, the bottom of the graphite furnace core is communicated with the discharging hole, and the graphite furnace core comprises a graphite furnace plate 23, a graphite reaction cylinder 28 and a liquid drainage unit; the top of the graphite reaction cylinder is coaxially and fixedly connected with a graphite furnace plate, and the bottom of the graphite reaction cylinder is fixedly inserted with a liquid discharge unit communicated with the discharge hole.

Moreover, the liquid drainage unit comprises a graphite column 29 and a liquid collection box 211, wherein the circumferential outer wall of the graphite column is in clearance fit connection with the circumferential inner wall of the graphite reaction cylinder, a plurality of spiral liquid drainage grooves 215 communicated with the top surface and the bottom surface of the graphite column are formed in the circumferential outer wall of the graphite column, and the bottom of the graphite column is fixedly connected with the liquid collection box in a sealing manner; the top surface of the liquid collecting box is provided with a plurality of liquid discharging holes 214 communicated with the spiral liquid discharging groove, the side wall of the liquid collecting box is sealed and fixedly supported by a ceramic sleeve, and the bottom of the liquid collecting box is communicated with the discharging hole.

And, a plurality of thermocouple sheaths 210 for penetrating and installing thermocouples are radially penetrated and fixedly installed on the reaction furnace cylinder, one end of each thermocouple sheath radially penetrates through the coil heating layer, the quartz sand heat-insulating layer and the ceramic sleeve and is attached to the circumferential outer wall of the graphite furnace core, and the other end of each thermocouple sheath extends towards the outside of the reaction furnace cylinder.

The granularity regulating and controlling device comprises a cylindrical barrel 51, a conical screen 57 and a grinding and screening unit, wherein the top and the bottom of the cylindrical barrel are sealed, the conical screen with the large-diameter end arranged upwards is coaxially and fixedly arranged in the middle of the cylindrical barrel, a motor 513 for providing rotary power for the grinding and screening unit is arranged at the bottom of the conical barrel, and a feeding port 55 communicated with the interior of the conical screen is fixedly arranged at the top of the conical barrel; the conical screen divides the interior of the conical cylinder into a plurality of material screening areas, and the material screening areas comprise a grinding area in the conical screen, a fine material area 517 at a crack between the conical screen and the inner wall of the cylindrical cylinder, and a coarse material area 512 at the bottom of the conical screen; the outer wall of the cylindrical barrel is fixedly provided with a plurality of fans 516 which are respectively communicated with the coarse material area and the fine material area, and the outer wall of the cylindrical barrel is provided with a plurality of discharge holes 514 which are respectively communicated with the coarse material area and the fine material area.

Moreover, a sealing plate 53 for sealing the opening at the top of the cylindrical barrel is coaxially and fixedly arranged at the top of the conical screen, and a plurality of layers of grinding plates 511 are coaxially and fixedly arranged in the conical screen; the periphery of the grinding plate is fixedly supported with a conical screen, the edge of the grinding plate is provided with feed openings 58 which are communicated along the gravity direction, and the feed openings on the adjacent grinding plates are arranged in a staggered way.

Moreover, the grinding and screening unit comprises a rotating shaft 54, a rotating vane plate 56 and a grinding roller 510, wherein the top end of the rotating shaft is rotatably connected with a cross beam 52 at the top of the cylindrical barrel, the middle part of the rotating shaft downwards coaxially penetrates through the sealing plate, the plurality of grinding plates and the coarse material area in sequence, the bottom of the rotating shaft is rotatably connected with the bottom plate of the cylindrical barrel, the lower part of the rotating shaft is in power connection with the output end of the motor 513 through a transmission belt 515, and the rotating shaft positioned in the conical barrel is sleeved with the plurality of rotating vane plates; the bottom of the rotating blade plate is rotatably connected with a plurality of grinding rollers, and the grinding rollers are matched with the top surface of the grinding plate to grind materials.

And, the rotating vane is axisymmetric and fixed on the rotating shaft, and the two ends of the rotating vane are provided with ejection slopes 59 which are matched with the section gradient of the conical screen.

Moreover, the transfer bin comprises a hopper 42 and a wheel carrier 41 for movably hanging the hopper; hanging lugs 44 extending downwards are fixedly arranged on two sides of the top of the wheel frame, a buffer supporting unit arranged along the horizontal direction is arranged on the side wall of the middle part of the wheel frame, and a wheel shifting motor 412 is fixedly arranged at the bottom of the wheel frame; swing shafts 43 which penetrate through and are rotatably connected to the hanging lugs are symmetrically and fixedly arranged on two sides of the upper part of the hopper, an impact cushion plate 45 of an impact buffering supporting unit is fixedly arranged on the side wall of the middle part of the hopper, and a shifting rod 413 which extends along the horizontal direction is fixedly arranged on the side wall of the bottom of the hopper; the output end of the shifting wheel motor is coaxially and fixedly provided with a shifting wheel 411, and the circumferential outer wall of the shifting wheel is connected with the circumferential outer wall of the shifting rod in a sliding fit manner.

The buffer support unit comprises a support beam 410, a support plate 49, a buffer spring 48 and an impact plate 47, wherein the support beam is fixedly arranged on the wheel frame along the horizontal direction, and the support plate is fixedly connected on the side wall of the support beam facing the interior of the wheel frame; the middle part of the supporting plate is fixedly connected with a buffer spring along the horizontal direction, and the free end of the buffer spring is fixedly connected with an impact plate; a rubber pad 46 is bonded to the impact plate.

Also, one side of the impact pad is formed as a tapered arc 418, and the other side is formed as an impact plane 417 that impacts the rubber pad.

And, a push rod 416 horizontally extending to the outside of the wheel frame is fixedly connected to one side of the top of the wheel frame, a hook 414 is movably sleeved on the push rod, and a positioning pin 415 for positioning the hook is penetratingly connected to the push rod.

Moreover, the transfer bin elevator comprises a frame 31, wherein one side of the frame is a feeding side, and the other side of the frame is a discharging side; the elevator also comprises a front shaft chain 33, a rear shaft chain 32 and a plurality of chain plates 34, wherein the two side walls in the rack are symmetrically and rotatably connected with the rear shaft chain, and the middle part of the rack is symmetrically and rotatably connected with the front shaft chain; front connecting frames 313 are symmetrically and fixedly connected to the bottom surfaces of the two sides of the front end of the chain plate in the conveying direction, and rear connecting frames 314 are symmetrically and fixedly connected to the bottom surface of the middle part of the rear end of the chain plate in the conveying direction; the front connecting frame is rotationally connected with a front shaft chain, and the front shaft chain is hung on the bottom of the rack and the side wall of the discharge side of the rack in an L shape; the rear axle roller is rotationally connected with a rear axle chain, and the rear axle chain is hung on the rack in a square shape; the chain plates are fixedly provided with a plurality of limiting plates 35, and the plurality of limiting plates jointly enclose a lifting limiting area 316 of the transfer bin.

Moreover, the bottom of the feeding side of the frame, the bottom of the discharging side of the frame and the top of the discharging side of the frame are all rotationally connected with a through shaft 37, and the two side walls of the frame are all symmetrically and rotationally connected with a front chain supporting wheel 39, a front chain tensioning wheel 38, a rear chain tensioning wheel 311 and a rear chain jacking wheel 36; the two ends of the through shaft are symmetrically and coaxially fixedly connected with a rear chain driving wheel 312, and the middle part of the through shaft is symmetrically and coaxially fixedly connected with a front chain driving wheel 310.

And one end of the through shaft is connected with a motor.

Moreover, the link plate comprises a plurality of slats 315 which are arranged in parallel and are hinged in sequence; the front shaft roller is oppositely and fixedly arranged on the bottom surface of a first batten at the front end of the chain plate in the conveying direction; the rear shaft roller is fixedly arranged on the bottom surface of the first batten at the rear end in the conveying direction of the chain plate in a back-to-back mode; and a limiting plate protruding upwards is fixedly arranged on the lath in the middle of the chain plate.

A method for preparing sodium monofluorophosphate by a sodium monofluorophosphate production system comprises the following steps:

In addition, the cooling machine, the crushing machine and the packaging machine are preferably mature products in the prior art.

In order to more clearly illustrate the embodiments of the present invention, several examples are provided below:

according to the raw material mixing and blending device for the sodium monofluorophosphate production system, the plurality of spiral feeders at the top of the mixing tank convey different-component raw materials to the inner cavity of the mixing tank through the slope-shaped feed port, the rotating speeds of the plurality of spiral feeders can be adjusted to control the raw material ratio, the raw materials are extruded downwards by the slope surface of the inner end surface of the raw materials after entering the slope-shaped feed port and then smoothly fall into the mixing tank, and the spiral feeders cannot be stacked at the outlet of the spiral feeders and then are blocked. Furthermore, the first motor and the second motor are controlled to rotate reversely, so that the outer stirring ring and the inner stirring ring are driven to rotate reversely, and it is noted that the first shaft lever and the second shaft lever are disconnected in the middle and only supported by the shaft seat in a rotating manner, and the first shaft lever and the second shaft lever are fixedly sleeved with a fixed support ring and a rotating support ring respectively, so that the first shaft lever and the second shaft lever can be limited in the radial direction, the top and the bottom of the V-shaped stirring blade can be fixedly supported, the structural strength is improved, the stress requirement in the stirring process is met, and the stirring unit is prevented from being deformed; and finally, sending out the fully stirred raw materials by a spiral feeder at the bottom of the mixing tank.

The invention relates to a melting reaction furnace for a sodium monofluorophosphate production system, which is characterized in that a powdery mixed material is continuously fed from a feeding hole at the top, the powdery mixed material is gradually changed into molten sodium monofluorophosphate in a graphite reaction cylinder, in order to avoid incomplete reaction of the sodium monofluorophosphate caused by nonuniform heating of the powdery mixed material, a graphite column is spliced at the bottom of the graphite reaction cylinder and is used for prolonging the detention time of the powdery mixed material in the graphite reaction cylinder and increasing the heating area of the powdery mixed material, and finally the powdery mixed material which is continuously fed from the feeding hole after the powdery mixed material is molten provides downward power, is fully melted and reacted in a spiral liquid discharge groove arranged at the periphery of the graphite column, is collected by a liquid discharge hole and a liquid collection box, and is discharged with the molten sodium monofluorophosphate from the discharging hole.

It should be noted that, because the periphery of the graphite column is in clearance fit with the inner wall of the graphite reaction cylinder, the material at the top of the graphite column can only flow downwards to the liquid collecting box through the spiral liquid discharging groove, so the downward flowing speed of the material depends on the heat degree of the graphite reaction cylinder and the feeding speed and pressure of the feeding port, and the invention is preferable, 4 spiral liquid leaking grooves are arranged on the circumferential outer wall of the graphite column, the number, depth and width of the spiral liquid leaking grooves need to be adjusted according to the size and heating efficiency of the graphite reaction cylinder in the most proper proportion, so that after the sodium monofluorophosphate fully reacts, the purity, PH value and free fluorine content of the sodium monofluorophosphate meet the standard requirements, and the continuous production efficiency of the sodium monofluorophosphate is improved.

According to the granularity regulating and controlling device for the sodium monofluorophosphate production system, when granularity is checked, a motor is started, sodium monofluorophosphate particles with uneven granularity after being crushed by a crusher are put into a grinding area in a conical screen through a feeding port, then the motor drives a rotating shaft and a rotating blade plate to rotate, the sodium monofluorophosphate particles meeting the granularity requirement are extruded by a material ejecting slope surface to penetrate through the conical screen and fall into a fine material area for temporary storage in the rotating process of the rotating blade plate, and the sodium monofluorophosphate particles are blown by a fan and are discharged through a discharge port; the rotating blade plate rotates and simultaneously drives the grinding roller to rotate and rub on the grinding plate so as to grind and crush large sodium monofluorophosphate particles, the materials with qualified granularity after grinding penetrate through the conical screen and are discharged through the fine material area, the large sodium monofluorophosphate particles with unqualified granularity fall into the grinding area of the next layer through the feed opening to be ground and screened again, and the process is repeated until the caking of the sodium monofluorophosphate with overlarge granularity or overlarge particle hardness is discharged from the coarse material area.

It should be noted that, feed opening staggered arrangement on the multilayer lapping plate avoids the sodium monofluorophosphate large granule directly to fall into to the coarse fodder district through the multilayer feed opening, effectively prolongs the detention time of sodium monofluorophosphate large granule in the inside grinding zone of conical screen, has realized accurate high-efficient granularity screening function, and the broken function of sodium monofluorophosphate large granule grinding.

According to the transfer bin for the sodium monofluorophosphate production system, the opening at the top of the hopper is used for feeding, the opening at the bottom is used for discharging, the manual plate valve is arranged at the opening at the bottom of the hopper, the transfer bin is firstly placed at the discharging port of the crushing equipment to contain crushed powdered sodium monofluorophosphate, then the push rod is pushed manually, the transfer bin is pushed to the transfer preparation area to be placed still, the hook on the push rod is hung at a fixed position during the placement, the wheel carrier is prevented from sliding, and finally, the transfer bin can be automatically vibrated under the condition of no human supervision by starting the deflector rod motor. In the vibration process, the wheel carrier and the hanging lugs on the wheel carrier provide rotary support for the hopper and the swing shaft, the shifting wheel motor and the shifting wheel provide swing power for the shifting rod and the bottom of the hopper, the impact base plate in the middle of the hopper directly impacts the rubber pad of the buffer support unit, and the buffer spring provides reset power for the hopper.

The conveying direction and the position of the inlet and outlet of the transfer bin are shown by arrows in fig. 15, the front shaft chain and the rear shaft chain rotate clockwise at the same speed, the operation positions of the chain plates driven by the front shaft chain are sequentially shown in fig. 16, 18 and 20, and the operation positions of the chain plates driven by the rear shaft chain are sequentially shown in fig. 17, 19 and 21.

It should be noted that when the chain plate performs the ascending action in the middle of the frame, the front end and the rear end of the operation direction are driven to be lifted by the front shaft chain and the rear shaft chain respectively at the same speed, so that the chain plate is always kept in a horizontal posture, and a transfer bin is placed in a lifting limit area on the chain plate, thereby preventing the transfer bin from toppling over or sliding out of the chain plate.

The invention relates to a production system and a preparation method of toothpaste grade sodium monofluorophosphate, and the components of the production system and the preparation method comprise the following conditions that the optimal proportion of sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide is shown in a table 1:

TABLE 1 list of sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide ratios

Serial number	Sodium hexametaphosphate	Sodium fluoride	Phosphorus pentoxide	Free fluorine content	pH value	Specification of
							1	900	352	41	0.23	6.85	Specification one
2	900	352	36	0.23	7.01	Specification one
							3	900	352	30	0.24	7.12	Specification one
4	1100	575	62	0.53	6.80	Standard No. two
							5	1100	534	62	0.46	6.79	Standard No. two
6	1100	497	62	0.39	6.80	Standard No. two

In the first specification: 800 portions of sodium hexametaphosphate; 300 portions and 450 portions of sodium fluoride; 30-50 parts of phosphorus pentoxide;

in the second specification: 800 portions of sodium hexametaphosphate; 600 portions of sodium fluoride 450; 50-70 parts of phosphorus pentoxide.

Comparing the detection results of

serial numbers

1, 2 and 3, the increase of the feeding amount of the phosphorus pentoxide can reduce the PH, because the phosphorus pentoxide is phosphoric acid anhydride and generates phosphoric acid when meeting water, the PH in the detection results is low, and the influence on the index of the free fluorine content is very small.

② comparing the detection results of

serial numbers

4, 5 and 6, the content of free fluorine will be increased by increasing the amount of sodium fluoride, because there will be trace sodium fluoride not consumed in the product, and the fluorine in the sodium fluoride is free fluorine when meeting water, so the content of free fluorine is large in the detection process, and the influence on the index of the pH value is very small.

The influence of the raw material mixing time on the indexes is as follows:

taking the formulation with number 1 in table 1 as an example, different mixing times in the mixing process were tested, and the test values are shown in table 2:

TABLE 2 influence of different mixing times on various values of sodium monofluorophosphate

Comparing the detection results of the

serial numbers

1, 2 and 3, when the material mixing time is 30min, the product has high content of sodium monofluorophosphate, high content of combined fluorine and low content of free fluorine, and the indexes of the product meet the national standard. This is because the raw material mixing time is long, the sodium fluoride consumption in the synthesis process is large, and the reaction is complete.

And secondly, comparing detection results of the

serial numbers

1, 2 and 3, when the material mixing time is 30min, the pH value of the sodium monofluorophosphate product is high, and indexes of the sodium monofluorophosphate product meet the national standard. This is because the raw material mixing time is long, phosphorus pentoxide is consumed in the synthesis process, and the reaction is complete.

Finally, it should be noted that, in the present invention, phosphorus pentoxide is used as one of the main raw materials, and the main functions are two: firstly, moisture in the air is absorbed, and the main reaction is ensured to be carried out smoothly. And secondly, the sodium fluoride and sodium pyrophosphate generated by side reaction are further reacted to generate sodium monofluorophosphate, so that the product purity of the sodium monofluorophosphate is improved, and the impurity content is reduced.

The raw materials adopted by the invention are sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide. The reaction equation is as follows:

the addition of phosphorus pentoxide enabled the conversion of the by-product formed to sodium monofluorophosphate:

the toothpaste grade sodium monofluorophosphate product produced by the method has the advantages that the content, free fluorine, pH value and water-insoluble substances in indexes are optimized compared with the data in the national standard. See table below:

TABLE 3 comparison of national standard index and technical index of the present invention

In addition to the above data, other indexes all meet the national standard.

In the production equipment, the inner wall of the equipment which is in direct contact with the materials is made of 304 stainless steel, so that the metal impurity content and the water insoluble substance data of the product are guaranteed to reach the standard.

The raw material sodium hexametaphosphate for producing the toothpaste grade sodium monofluorophosphate in the invention meets the technical requirements in GB 1886.4-2015 food additive sodium hexametaphosphate; the raw material sodium fluoride meets the technical requirements in HG/T5210-2017; the raw material phosphorus pentoxide should meet the technical requirements of analyzing pure phosphorus pentoxide in GB/T2305-2000. The indexes such as impurity content, PH value and the like are controlled from the raw materials, so that the sodium monofluorophosphate prepared from the raw materials with the technical requirements can meet the technical indexes of the national standard GB24567-2009 sodium monofluorophosphate for toothpaste industry.

In addition, the invention adopts mature products in the prior art and mature technical means in the prior art.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.

Claims

1. A production system of sodium monofluorophosphate which is characterized in that: the production system comprises a raw material mixing and blending device, a melting reaction furnace, a cooling machine, a crushing machine, a granularity regulating and controlling device, a packing machine, a transfer bin for transferring materials on a production line and a transfer bin lifter, wherein the feed end of the raw material mixing and blending device is used for adding sodium hexametaphosphate, sodium fluoride and phosphorus pentoxide in different parts by weight and fully mixing the sodium hexametaphosphate, the sodium fluoride and the phosphorus pentoxide, the discharge end of the raw material mixing and blending device is communicated with the melting reaction furnace, liquid sodium monofluorophosphate after melting reaction is introduced into the cooling machine for cooling and solidification and then introduced into the crushing machine for crushing, the qualified sodium monofluorophosphate is screened out through the granularity regulating and controlling device, and finally the finished product sodium monofluorophosphate is introduced into the packing machine; the transfer bin hoister is arranged between the melting reaction furnace and the crusher and used for lifting the transfer bin and supplying materials to the crusher; the transfer bin is used for transferring and conveying materials among the raw material mixing and blending device, the melting reaction furnace, the cooler, the pulverizer, the granularity regulating and controlling device and the packaging machine;

the middle part of the material mixing and blending device is coaxially connected with a stirring unit in a penetrating manner, a plurality of slope feeding holes are radially formed in the upper part of the material mixing tank, a plurality of spiral feeders extending into the slope feeding holes are fixedly arranged on the upper part of the material mixing tank, and spiral feeders extending into the material mixing tank are fixedly arranged on the lower part of the material mixing tank along the horizontal direction; the stirring unit comprises a first motor, a first shaft lever, an outer stirring ring, a second motor, a second shaft lever and an inner stirring ring, wherein the first motor is coaxially and fixedly arranged at the top of the material mixing tank, the first shaft lever extending downwards into the material mixing tank is coaxially and fixedly arranged at the output end of the first motor, and the outer stirring ring is coaxially and fixedly arranged on the first shaft lever; the second motor is fixedly arranged below the mixing tank and is in power connection with the power input end of the second shaft lever through a driving belt; the second shaft rod extends upwards into the mixing tank, the top of the second shaft rod is coaxially and rotatably connected with the bottom end of the first shaft rod through a shaft seat, and an inner stirring ring is coaxially and fixedly arranged on the second shaft rod; the bottom of the outer stirring ring is connected with the second shaft rod in a rotating fit manner, and the top of the inner stirring ring is connected with the first shaft rod in a rotating fit manner; the outer stirring ring and the inner stirring ring respectively comprise a fixed support ring, a rotary support ring and V-shaped stirring blades, wherein the opening ends of the V-shaped stirring blades are arranged towards the axle center of the mixing tank, one ends of the V-shaped stirring blades are fixedly connected with the fixed support ring, and the other ends of the V-shaped stirring blades are fixedly connected with the rotary support ring; the fixed support ring of the outer stirring ring is coaxially and fixedly arranged with the first shaft rod, and the rotary support ring of the outer stirring ring is rotatably sleeved on the outer wall of the second shaft rod through a bearing; the fixed support ring of the inner stirring ring and the second shaft rod are coaxially and fixedly arranged, and the rotary support ring of the inner stirring ring is rotatably sleeved on the outer wall of the first shaft rod through a bearing; the inner wall of the end face of the slope feeding hole is a slope surface which inclines downwards towards the axis direction of the mixing tank, the slope surface is in rotating fit with a rotating shaft of the spiral feeder, and the spiral feeder fills raw materials into the mixing tank through the slope feeding hole;

the melting reaction furnace comprises a reaction furnace barrel, wherein an insulating bottom support with a discharge hole is axially packaged at the lower part of the reaction furnace barrel, an insulating top cover with a feed hole is axially packaged at the upper part of the reaction furnace barrel, and a coil heating layer, a quartz sand heat-insulating layer, a ceramic sleeve and a graphite furnace core are coaxially sleeved in sequence in the middle of the reaction furnace barrel; the top of the graphite furnace core is communicated with the feeding hole, the bottom of the graphite furnace core is communicated with the discharging hole, and the graphite furnace core comprises a graphite furnace disc, a graphite reaction cylinder and a liquid drainage unit; the top of the graphite reaction cylinder is coaxially and fixedly connected with a graphite furnace plate, and the bottom of the graphite reaction cylinder is fixedly inserted with a liquid discharge unit communicated with the discharge hole; the liquid discharge unit comprises a graphite column and a liquid collection box, wherein the circumferential outer wall of the graphite column is in clearance fit connection with the circumferential inner wall of the graphite reaction cylinder, a plurality of spiral liquid discharge grooves communicated with the top surface and the bottom surface of the graphite column are formed in the circumferential outer wall of the graphite column, and the bottom of the graphite column is fixedly connected with the liquid collection box in a sealing manner; the top surface of the liquid collecting box is provided with a plurality of liquid discharging holes communicated with the spiral liquid discharging groove, the side wall of the liquid collecting box is sealed and fixedly supported by a ceramic sleeve, and the bottom of the liquid collecting box is communicated with the discharging hole; the bottom surface of the insulating top cover is hermetically sealed and fixedly pressed on the coil heating layer and the top surface of the quartz sand heat-insulating layer, a ceramic sleeve is fixedly inserted on the bottom surface of the insulating top cover, and a graphite reaction cylinder is fixedly penetrated in a discharge port of the insulating top cover; a graphite furnace plate is coaxially and fixedly arranged at the opening at the top of the graphite reaction cylinder, and the bottom surface of the graphite furnace plate is fixedly lapped on the top surface of the insulating top cover; a plurality of thermocouple sheaths for penetrating and installing thermocouples are radially penetrated and fixedly installed on the reaction furnace cylinder, one end of each thermocouple sheath radially penetrates through the coil heating layer, the quartz sand heat insulation layer and the ceramic sleeve and is attached to the circumferential outer wall of the graphite furnace core, and the other end of each thermocouple sheath extends towards the outside of the reaction furnace cylinder;

the particle size regulating device comprises a cylindrical barrel, a conical screen and a grinding and screening unit, wherein the top and the bottom of the cylindrical barrel are sealed, the conical screen with the large diameter end arranged upwards is coaxially and fixedly installed in the middle of the cylindrical barrel, a motor for providing rotary power for the grinding and screening unit is arranged at the bottom of the conical barrel, and a feed port communicated with the interior of the conical screen is fixedly installed at the top of the conical barrel; the conical screen divides the interior of the conical cylinder into a plurality of material screening areas, and the material screening areas comprise a grinding area in the conical screen, a fine material area at a crack between the conical screen and the inner wall of the cylindrical cylinder and a coarse material area at the bottom of the conical screen; the outer wall of the cylindrical barrel is fixedly provided with a plurality of fans which are respectively communicated with the coarse material area and the fine material area, and the outer wall of the cylindrical barrel is provided with a plurality of discharge holes which are respectively communicated with the coarse material area and the fine material area; a sealing plate for sealing the opening at the top of the cylindrical barrel is coaxially and fixedly arranged at the top of the conical screen, and a plurality of layers of grinding plates are coaxially and fixedly arranged in the conical screen; the periphery of the grinding plate is fixedly provided with a conical screen, the edge of the grinding plate is provided with feed openings which are communicated along the gravity direction, and the feed openings on the adjacent grinding plates are arranged in a staggered manner; a feed opening on the grinding plate at the lowermost layer of the conical screen is communicated with the coarse material area; the grinding and screening unit comprises a rotating shaft, a rotating blade plate and a grinding roller, wherein the top end of the rotating shaft is rotatably connected with a cross beam at the top of the cylindrical barrel, the middle part of the rotating shaft downwards coaxially penetrates through the sealing plate, the plurality of grinding plates and the coarse material area in sequence, the bottom of the rotating shaft is rotatably connected with the bottom plate of the cylindrical barrel, the lower part of the rotating shaft is in power connection with the output end of the motor through a transmission belt, and the rotating shaft positioned in the conical barrel is sleeved with the plurality of rotating blade plates; the bottom of the rotating blade plate is rotatably connected with a plurality of grinding rollers, and the grinding rollers are matched with the top surface of the grinding plate to grind materials; the rotating vane plate is axisymmetric and fixedly sleeved on the rotating shaft, and two ends of the rotating vane plate are provided with ejection slopes matched with the gradient of the section of the conical screen.

2. The system for producing sodium monofluorophosphate according to claim 1, wherein: the transfer bin comprises a hopper and a wheel carrier movably connected with the hopper; the two sides of the top of the wheel carrier are fixedly provided with hanging lugs extending downwards, the side wall of the middle part of the wheel carrier is provided with a buffer supporting unit arranged along the horizontal direction, and the bottom of the wheel carrier is fixedly provided with a thumb wheel motor; swing shafts which penetrate through and are rotatably connected to the hanging lugs are symmetrically and fixedly arranged on two sides of the upper part of the hopper, an impact cushion plate of an impact buffering supporting unit is fixedly arranged on the side wall of the middle part of the hopper, and a deflector rod which extends along the horizontal direction is fixedly arranged on the side wall of the bottom of the hopper; the output end of the shifting wheel motor is coaxially and fixedly provided with a shifting wheel, and the circumferential outer wall of the shifting wheel is connected with the circumferential outer wall of the shifting rod in a sliding fit manner; the buffer support unit comprises a support beam, a support plate, a buffer spring and an impact plate, wherein the support beam is fixedly arranged on the wheel frame along the horizontal direction, and the support plate is fixedly connected to the side wall of the support beam facing the interior of the wheel frame; the middle part of the supporting plate is fixedly connected with a buffer spring along the horizontal direction, and the free end of the buffer spring is fixedly connected with an impact plate; a rubber pad is compositely bonded on the impact plate; one side of the impact pad plate is made into a conical cambered surface, and the other side of the impact pad plate is made into an impact plane of the impact rubber pad; one side of the top of the wheel carrier is fixedly connected with a push rod which horizontally extends to the outside of the wheel carrier, the push rod is movably sleeved with a hook, and the push rod is penetratingly connected with a positioning pin for positioning the hook.

3. The system for producing sodium monofluorophosphate according to claim 1, wherein: the transfer bin elevator comprises a frame, wherein one side of the frame is a feeding side, and the other side of the frame is a discharging side; the elevator also comprises a front shaft chain, a rear shaft chain and a plurality of chain plates, wherein the two side walls in the rack are symmetrically and rotatably connected with the rear shaft chain, and the middle part of the rack is symmetrically and rotatably connected with the front shaft chain; front connecting frames are symmetrically and fixedly connected to the bottom surfaces of the two sides of the front end of the chain plate in the conveying direction, and rear connecting frames are symmetrically and fixedly connected to the bottom surface of the middle part of the rear end of the chain plate in the conveying direction; the front connecting frame is rotationally connected with a front shaft chain, and the front shaft chain is hung on the bottom of the rack and the side wall of the discharge side of the rack in an L shape; the rear axle roller is rotationally connected with a rear axle chain, and the rear axle chain is hung on the rack in a square shape; a plurality of limiting plates are fixedly arranged on the chain plates, and the plurality of limiting plates jointly enclose a lifting limiting area of the transfer bin; the bottom of the feeding side of the rack, the bottom of the discharging side of the rack and the top of the discharging side of the rack are respectively and rotatably connected with a through shaft, and the two side walls of the rack are respectively and symmetrically connected with a front chain supporting wheel, a front chain tensioning wheel, a rear chain tensioning wheel and a rear chain jacking wheel in a rotating manner; the two ends of the through shaft are symmetrically and coaxially fixedly connected with a rear chain driving wheel, and the middle part of the through shaft is symmetrically and coaxially fixedly connected with a front chain driving wheel; the front shaft chain is respectively wound on the front chain driving wheels at the two ends of the through shaft, the middle corner of the front shaft chain rotates and is connected with the front chain tension wheel in a propping and supporting manner, and the lower part of the front shaft chain rotatably supports the front chain support wheel; the rear shaft chain is respectively wound on a rear chain driving wheel in the middle of the through shaft and a rear chain jacking wheel on the upper part of the feeding side of the rack, and the rear shaft chain rotates on the outer wall close to the feeding side of the rack and supports the rear chain tensioning wheel in a jacking mode; one end of each through shaft is connected with a motor; the chain plate comprises a plurality of laths which are arranged in parallel and are hinged in sequence; the front shaft roller pair is fixedly arranged on the bottom surface of a first batten at the front end of the chain plate in the conveying direction; the rear shaft roller is fixedly arranged on the bottom surface of the first batten at the rear end in the conveying direction of the chain plate in a back direction; and a limiting plate protruding upwards is fixedly arranged on the lath in the middle of the chain plate.

4. A method for preparing sodium monofluorophosphate by using the sodium monofluorophosphate production system of claim 1, which is characterized in that: the method comprises the following steps:

5. The method of claim 4, wherein the sodium monofluorophosphate is selected from the group consisting of: the synthesis procedure of the second step comprises a plurality of reactions which are carried out simultaneously, and the reaction equation is as follows:

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