JP2005344204A - Method and apparatus for recovering solder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To recover solder from dross floating on molten solder in a solder bath in a short period of time at high recovery rate. <P>SOLUTION: The solder recovery apparatus 10 is an apparatus for recovering the solder by vacuum-sucking the dross 3 floating on the molten solder 2 in the solder bath 1. This apparatus 10 comprises: a suction section 20 for a suction nozzle 21; a spray section 30 for causing steam explosion by spraying water onto the dross 3 sucked via the suction nozzle 21 to pulverize the dross 3 into dross particles 3a and solder particles 2a; a separation section 40 for separating the dross particles 3a from the solder particles 2a by the difference in specific gravity; and a recovery section 50 for separately recovering the separated dross particles 3a and the solder particles 2a in containers 51 and 52, respectively. Further, in the apparatus 10, a cart-type main body 11 freely movable on the floor is equipped with the above sections. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method and apparatus for recovering solder mixed in dross from dross floating on molten solder in a solder bath.

  In recent years, as an environmental measure, in the solder industry, lead-free free of lead has become widespread. Further, when a soldering process for a printed circuit board or the like is performed with molten solder in a solder bath, porous dross that is an oxide compound or a nitride compound is generated on the liquid surface of the molten solder. Since the reusable granular solder is mixed in the dross, the solder is collected from the dross and regenerated. In particular, lead-free solder is several times more expensive than eutectic solder containing lead, and sherbet-like dross is generated about 1.5 to 1.8 times that of eutectic solder, of which about 50% is solder. Therefore, the solder recovery is actively performed by a solder user or a solder recycler.

  A typical method for recovering solder from dross is to collect dross floating on the molten solder in the solder bath to form a dross lump. (For example, refer to Patent Document 1). At present, the solder is collected in the following procedures (1) to (3), and the molten solder in the solder tank is replenished.

(1) When the soldering operation is completed with the molten solder in the solder bath, the worker scoops out the dross floating on the molten solder with a handle, and transfers it to a heat-resistant container, which is solidified by natural cooling to form a dross lump.

(2) The dross lump is put in a melting tank similar to the solder tank and heated, and the granular solder in the dross is remelted together with the dross to bond the solders together. Accumulate on the bottom and float the dross on it. The floated dross is scraped with a handle and the molten solder under the dross is pumped up, placed in an ingot mold and naturally cooled to obtain a rod-like recovered solder lump. When heating the dross mass in the melting tank, an additive such as sesame is added to the molten dross and stirred so that the granular solder mixed in the dross is easily melted and separated from the dross.

(3) The rod-like collected solder lump is stored, and the reclaimed solder lump is supplied to the molten solder in the solder tank when necessary, for example, during soldering operation in the solder tank. By this replenishment, the liquid level of the molten solder in the solder tank is maintained at a constant height, and a soldering operation for a printed circuit board or the like is performed.
JP 2000-192158 A

  The above solder recovery method still has the following technical and economic problems.

When melting the dross mass in the melting tank, melting the granular solder mixed in the dross, collecting it at the bottom of the melting tank, floating the dross on it, and collecting the molten solder at the bottom of the melting tank, Since the molten solder close to dross contains a lot of dross, recovery is inappropriate. Further, the dross melted in the melting tank and the solder cannot be completely separated. As a result, the recovery rate of solder from the dross is 50 to 70%. Although this recovery rate can be improved somewhat if much recovery is required, it is not realistic.

-When the collected bar-shaped solder lump is charged into the molten solder in the solder bath and replenished, the low temperature solder lump causes the temperature of the high-temperature molten solder to fall, making it difficult to control the temperature of the solder bath. In addition, the liquid level of the molten solder in the solder bath rises at a stroke due to the introduction of the bar-shaped solder lump, and it is difficult to manage the liquid level in order to keep this liquid level at a certain level. It is also possible to replenish the molten solder in the solder bath with commercially available linear solder instead of the bar-shaped solder lump. However, linear solder is expensive and is economical in solder baths that consume a large amount of solder. Burden is large.

-The dross floating on the molten solder in the solder bath is hot, and the work of the solder bath line manager to handle it with a handle is heavy and the work time is long. In particular, in the case of lead-free solder, the amount of dross is large, the dross scraping work time is doubled, the work load is increased, and a single worker becomes a half-day job, resulting in high labor costs. Also, the operation of collecting solder from the dross is off-line due to smoke generation, and it takes about half a day for the dross treatment for one day, so that a dedicated worker is required and the labor cost is further increased.

・ It has been found that the soldering quality of molten solder in the solder bath is improved by dividing the dross several times a day and scraping it frequently. However, dross scraping several times a day is a manual operation under high temperature and is forgotten due to poor workability. At present, since the dross is scraped once a day after the soldering operation in the solder tank is finished, the soldering quality is likely to be deteriorated.

-The melting tank for heating and remelting the dross mass is smaller than the solder tank, but requires an expensive heat-resistant structure similar to the solder tank. Moreover, when a dross lump is heated and melted in a melting tank, an additive such as sesame is added, but smoke emission equipment is required because the additive emits smoke. If this smoke exhausting equipment is included, the equipment required for collecting the solder from the dross becomes large and the equipment cost increases.

-The running cost is high due to the power to heat and remelt the dross mass and the additives such as sesame.

  An object of the present invention is to provide a solder recovery method and a recovery apparatus that are technically and economically superior.

  The method of the present invention to achieve the above object is to smash the dross into dross grains and solder grains by vacuum sucking the solder-containing dross floating on the molten solder with a suction nozzle and spraying water on the dross immediately after the suction to cause a steam explosion. The solder grains are separated and recovered from the dross grains.

  Here, the suction nozzle vacuum sucks the dross in a vacuum cleaner manner. In the present invention, the tip of the suction nozzle can be immersed in the molten solder liquid level in the solder bath, and the dross in the nozzle tip can be vacuumed through an air hole formed in the side surface of the nozzle tip. In this case, a sensor is installed at the tip of the suction nozzle to detect the immersion depth of the tip into the molten solder liquid surface, and the suction nozzle moves horizontally relative to the molten solder based on the detection signal of this sensor. The dross can be continuously sucked by vacuum. Here, the sensor is an excessive penetration preventing sensor that prevents the suction nozzle from excessively penetrating the molten solder liquid surface. Based on the detection signal of the sensor, the suction nozzle is interlocked to maintain a certain height, and the suction nozzle is controlled so that the tip of the suction nozzle does not protrude too much into the liquid surface of the molten solder. It moves horizontally on the surface of the molten solder at a predetermined position and at a predetermined height.

  The dross floating on the molten solder in the solder tank is a porous fluid contained in the form of entraining the granular solder, and the suction nozzle continuously sucks the dross including the granular solder with an appropriate suction force. Particulate water is sprayed toward the dross immediately after being sucked by the suction nozzle, and the dross is pulverized by causing a steam explosion in the dross. The dross is pulverized by the rapid volume expansion of water vapor, resulting in a mixture of many dross grains of pure dross and solder grains of pure solder, and vacuum sucked from the suction nozzle to the suction hose, suction pipe, etc. Is done. Dross is a porous fluid body with a large number of small pores on its surface.When water particles are sprayed to the extent that they enter the small pores on the surface, the water particles that have entered the small pores suddenly become dross heat. When heated, the steam explodes, and the dross is crushed into a large number of dross grains and solder grains. The particle diameters of the dross grains and the solder grains are substantially the same, and the solder grains are granular solder that has been wound into the dross before pulverization. The dross grains are 100% dross grains, the solder grains are 100% solder grains, and basically do not fuse even when heated, and the solder grains are simply caught in the dross grains. . In the present invention, dross grains and solder grains are separated in a solid state and a large number of solder grains are collected. The separation of the dross grains and the solder grains can be performed with certainty by utilizing the specific gravity difference between the two.

  In the present invention, the dross grains obtained by pulverizing the dross and the solder grains can be centrifuged. When centrifugal force is applied to a mixture of a large number of dross grains and solder grains using a centrifuge, a difference occurs in the flying distance due to the centrifugal force of the solder grains having a small specific gravity and large specific gravity. Thus, dross grains and solder grains can be clearly separated, and a large number of separated dross grains and a large number of solder grains can be separately collected in respective collection containers, collection chutes and the like. The collected solder grains are 100% solder and are collected in the form of grains, so that handling is convenient. Since the dross is crushed into dross grains and solder grains, separated and collected, the solder can be recovered from the dross at a recovery rate close to 100%. Since a part of the solder grains is mixed on the dross grain side at the time of separation and recovery, the substantial solder recovery rate is slightly over 90% and does not fall below 90%.

  The collected solder particles can be stored as they are. Depending on the capacity of the solder tank and the suction force of the suction nozzle, suction of all dross from one solder tank can be completed within a few minutes, and dross grains and solder grains continuously immediately after dross suction. Therefore, the solder can be recovered automatically in a very short time. As a result, solder can be collected multiple times a day. For example, soldering operators can finish soldering once in the morning break, once in the lunch break, and once in the afternoon break. After that, the solder can be recovered once by dross suction and four times a day. If the solder is collected several times a day in this way, the purity of the molten solder in the solder bath is maintained, and the soldering quality is improved. Further, dross suction by the suction nozzle can be performed in a very short time, and further, a dedicated worker is not required, so that labor costs can be saved. In addition, it is not necessary to put a hand in the high-temperature solder bath facility, so the workload of the line manager is reduced.

  In the present invention, the stored collected solder particles can be replenished to the molten solder in the original solder tank or the molten solder in another solder tank when necessary. By supplying and replenishing the solder grains to the molten solder little by little, rapid temperature change and liquid level change of the molten solder are eliminated, and temperature management and liquid level management are facilitated. Also, the solder particles are collected from the dross, and when the solder user collects the solder, the replenishment solder can be produced in-house, which is extremely economical.

  In addition, the device of the present invention that achieves the above object includes a suction part having a suction nozzle for vacuum suction of the dross floating on the molten solder from the opening of the tip, and a dross installed on the inner periphery of the tip of the suction nozzle and sucked by the suction nozzle. The spray part having a spray nozzle that sprays water toward and crushes into dross grains and solder grains, a separation part that separates the dross grains and solder grains from the fluid flowing in the suction nozzle, and the separation part. It is characterized by a structure including a collection unit that collects dross grains and solder grains separately.

  Here, the suction unit includes a vacuum generation means such as a vacuum pump for vacuum suction of the suction nozzle, a suction hose connecting the vacuum generation means and the suction nozzle, a drive system that supports the suction hose and moves it up, down, left, and right. Includes a control system and a filter that removes water vapor and smoke from the fluid sucked into the suction hose. For example, the suction nozzle tip opening is pointed directly below, the tip of the suction nozzle is slightly immersed in the molten solder liquid level in the solder bath, and the suction system is interlocked with the drive system or control system so that it does not protrude too much into the molten solder. , The suction nozzle is horizontally moved to suck the dross continuously, and the control system controls the suction pressure, suction speed, air volume, etc. that do not suck only the dross and suck the molten solder, and displays it. The spray unit includes a water supply pump that pumps water to the spray nozzle provided at the tip of the suction nozzle, and a control system that variably controls and displays the particle size of water sprayed from the spray nozzle and the ejection speed. The separation unit separates the dross grains and the solder grains by a specific gravity difference, and a separation apparatus using a specific gravity liquid in which the dross grains float but the solder grains settle, and a centrifugal separation apparatus using centrifugal force can be applied. As the recovery unit, a container or chute that accommodates the separated dross grains and a container or chute that accommodates the solder grains can be applied.

  In the apparatus of the present invention, the centrifugal separator includes a bottomed inclined drum that contains dross grains and solder grains, and rotates at the bottom of the inclined drum so that the dross grains and solder grains are placed on the inner peripheral surface of the inclined drum. A rotating body that flies along a spiral, and has a structure that separates the dross grains and the solder grains by the difference in specific gravity while the dross grains and the solder grains are caused to fly on the inner peripheral surface of the inclined drum. it can. In this case, the rotating body at the bottom of the inclined drum is a screw-like one in which a plurality of blades project radially at predetermined intervals around the rotation axis. The inner surface of the inclined drum flew away as if it had been blown off by a plate, and the solder particles with large specific gravity flew farther and provided at the tip opening of the inclined drum or the drum inner surface near this tip opening. It is discharged from the collection hole and collected as it is. The other dross particles may be prevented from being discharged from the inclined drum, and may be collected together with water of spray water at the bottom of the drum when the rotating body is stopped, and extracted from the inclined drum and collected when necessary.

  In the device of the present invention, a check valve is provided between the suction nozzle tip of the suction nozzle tip and the spray nozzle to prevent the spray water from the spray nozzle from flowing back to the nozzle tip side. can do. The check valve here prevents the spray water from flowing down along the inner periphery of the nozzle tip and dropping into the molten solder when the dross floating on the molten solder is sucked with the suction nozzle directly below. Continue the dross suction operation. Such a check valve that rotates so as to open upward by the wind pressure during dross suction is effective in favoring continuous dross suction operation.

  Furthermore, in the apparatus of the present invention, a suction part, a spray part, a separation part, and a recovery part can be arranged on a cart-type main body that can be moved automatically or manually on the floor. The suction section here is provided with a replaceable filter (water vapor, smoke, fine dust, odor, etc.) to make the solder recovery work environment clean. Further, a cordless operation power supply unit can be provided in the main body.

  Such a cart-type solder recovery apparatus of the present invention freely moves between a plurality of solder tanks installed on the floor of a factory, and continuously performs dross suction and solder recovery operations in each solder tank. . In addition, if a cordless operation power supply unit is provided in the main body, cordless operation can be achieved, and it is safe because the power supply unit can continue continuous operation even if a power failure occurs during solder recovery operation.

  According to the present invention, the dross floating on the molten solder in the solder bath is directly sucked with a suction nozzle, and immediately after being crushed into dross grains and solder grains by water spraying and recovered as solder grains, the solder from the dross is collected. An excellent effect that the recovery rate can be improved to 90% or more can be obtained. Also, since the dross in the solder bath is vacuumed, dross suction and solder recovery can be performed in a short time within a few minutes, and dross suction and solder recovery can be performed many times a day, improving the soldering quality. In addition, labor saving can be facilitated and the labor cost for collecting the solder can be reduced. Furthermore, it can be collected and stored in the form of solder particles, and solder particles can be replenished to the molten solder in the solder bath as needed in an appropriate amount. This replenishment minimizes changes in molten solder temperature and liquid level. Since it can be suppressed, temperature management and liquid level height management at the time of solder replenishment in the solder bath are facilitated. Also, since the solder particles generated by crushing the dross in the solder bath are recovered and reused as they are, the power required for solder recovery can be reduced, and consumables such as additives are not used. Reduction is possible.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  A solder recovery apparatus 10 shown in FIG. 1 is of a cart type that runs on the floor 4 and has a box-shaped main body 11. The main body 11 is self-propelled on the floor 4 by the wheels 12. A solder tank 1 is installed on a floor 4 via a table 5, and a fixed amount of molten solder 2 is accommodated in the solder tank 1. The solder recovery apparatus 1 vacuum-sucks the dross 3 floating on the molten solder 2 with a suction nozzle 21 and recovers the solder entrained in the dross 3 in a granular state.

  The solder recovery apparatus 10 includes a suction unit 20 having a suction nozzle 21 at the top of the main body 11. The suction unit 20 is equipped with a vacuum generating means 27 of a vacuum pump P as shown in FIG. 2 at the top of the main body 11, and a suction nozzle 21 is connected to the tip of a suction path connected to the vacuum generating means 27. A filter (not shown) is replaceably disposed at the root portion of the suction path on the vacuum generating means 27 side, and a plurality of baffle plates 26 are installed in the suction path located in the upper center of the main body 11. A free pipe (suction pipe) 25 that can move up and down and right and left extends from the suction path where the baffle plate 26 is located, and the suction nozzle 21 is connected to the tip of the free pipe 25 so that the posture can be changed. The universal pipe 25 is driven and controlled up and down and left and right by a drive system 28 and a control system 29.

  The solder recovery apparatus 10 includes a spray unit 30 that sprays water droplets for dross crushing in the tip of the suction nozzle 21, and a water supply pump of the spray unit 30 is installed in the main body 11. In addition, the solder recovery apparatus 10 includes a separation unit 40 that separates the dross particles generated by pulverizing the dross sucked into the suction nozzle 21 with water spray from the solder particles, and the dross particles separated by the separation unit 40. A recovery unit 50 for separately recovering solder particles is provided in the main body 11.

  Specific examples of the suction nozzle 21 are shown in FIGS. The suction nozzle 21 is a stainless steel tube to which molten solder is difficult to adhere, and detects that a plurality of air holes 23 having the same axial length at the tip and the tip are immersed in the liquid surface of the molten solder 2. It has a sensor 24. The plurality of air holes 23 form the tip of the suction nozzle 21 in a circular comb shape. The sensor 24 has a pair of an upper electrode 24 a installed near the upper end of the air hole 23 and a lower electrode 24 b installed at the tip of the suction nozzle, and when the tip of the suction nozzle is immersed in the liquid surface of the molten solder 2. Based on the detection signal for the presence or absence of energization between the two electrodes, the immersion depth at the molten solder liquid surface of the suction nozzle tip is detected, and control such as interlock is performed to maintain this immersion depth at an appropriate value. . Such an electrode type sensor 24 has excellent heat resistance, stable performance and long life.

  In addition, a check valve 35 is installed at a fixed position slightly behind the air hole 23 in the tip of the suction nozzle 21, and a plurality of spray nozzles 31 are installed further inside. The check valve 35 is a movable valve that rotates upward in FIG. 2 with the suction pressure when the suction nozzle 21 sucks in vacuum. The spray nozzle 31 communicates with a water supply pipe 32 fixed to the outer periphery of the tip of the suction nozzle 21, and the water supply pipe 32 communicates with a water supply pump (not shown) to constitute the spray unit 30.

  The separation unit 40 accommodated in the main body 11 is a centrifuge provided with, for example, an inclined drum 41, a rotating body 42, and an electric motor 43, and is hereinafter referred to as a centrifuge 40. A solder collection container 51 and a dross collection container 52 are arranged on both sides of the centrifugal separator 40 in the main body 11 to constitute the collection unit 50. Further, a cordless operation power supply unit 60 is installed on a part of the bottom of the main body 11. The power supply unit 60 includes a rechargeable battery and a charging device, and is used as a driving power source or an emergency power source for the suction unit 20, the spray unit 30, and the centrifugal separator 40.

  Next, the operation of the above-described embodiment will be described.

  The operation of the solder tank 1 is temporarily stopped, the solder recovery device 10 is moved to the solder tank 1, and the tip of the suction nozzle 21 is immersed vertically in the molten solder 2 as shown in FIG. At this time, the tip of the suction nozzle 21 is immersed in the molten solder 2 so that the upper part of the air hole 23 of the suction nozzle 21 slightly protrudes above the dross 3. By lowering the suction nozzle 21 from directly above the dross 3 and dividing the dross 3 and immersing the tip of the nozzle in the molten solder 2, the nozzle tip is heated to the same temperature by the molten solder 2, making it difficult for the solder to arrive. The dross 3 split in the nozzle tip portion remains, and the dross 3 is easily sucked by vacuum.

  When the suction part 20 is operated in the state of FIG. 2, the inside of the suction nozzle 21 is vacuum-sucked, the outside air is sucked from the air hole 23 on the outer periphery of the tip part, and the suction speed rapidly rises in the nozzle tip part, and inside the nozzle tip part. It is easy to pull up the dross 3, and the dross 3 is rapidly sucked and raised continuously. In the state of FIG. 2, the suction nozzle 21 is interlocked by the drive system 28 and the control system 29, moves horizontally along the liquid surface of the molten solder 2 while performing a vacuum suction operation, and the dross 3 floating on the molten solder 2. Aspirate continuously. In order to prevent the molten solder 2 from being sucked by this vacuum suction, an upper limit value, a lower limit value, and an optimum value such as a suction pressure, a suction speed, and an air volume are set in advance based on experiments. Further, the drive system 28 and the control system 29 of the suction unit 20 are taught in advance so that the suction nozzle 21 maintains the posture shown in FIG.

  The check valve 35 opens upward by the wind pressure when the suction nozzle 21 sucks the dross 3, and the dross 3 passes. Immediately after this passage, water is sprayed from the spray nozzle 31 toward the dross 3. The dross 3 is hot. When water is sprayed on the dross 3, water particles enter from the small holes on the surface of the porous dross 3 and cause a steam explosion in the dross. The dross 3 is soldered with a large number of fine dross grains 3a and solder. The particles 2a are pulverized, and the dross particles 3a and the solder particles 2a are sucked and conveyed from the suction nozzle 21 into the free pipe 25 and the main body 11 together with water vapor while solidifying.

  Note that, when the dross 3 is pulverized by steam explosion in the state of FIG. 2, rapid volume expansion occurs, but this volume expansion has little influence on the flow of vacuum suction, and the continuous smooth vacuum suction operation is continued. . Also, as shown in FIG. 2, the nozzle inner diameter of the portion 22 where the dross 3 at the tip of the suction nozzle 21 is crushed by the steam explosion is set large, and the volume expansion due to the steam explosion is absorbed at this portion 22. By doing so, a smoother vacuum suction operation can be continued.

  The dross grains 3a and the solder grains 2a sucked into the main body 11 from the universal pipe 25 collide with the baffle plate 26 to change the course, and fall into the lower inclined drum 41 by colliding with the plurality of baffle plates 26. To do. Further, the water vapor and dust meander between the baffle plates 26 and are captured by a filter (not shown), and only the cleaned fluid is discharged.

  The tilting drum 41 of the centrifugal separator 40 is a cup with a bottom opening at the top opening whose center line is tilted at a predetermined angle, and has a rotating body 42 with a rotating blade structure at the bottom. When rotating, the dross grains and solder grains between the blades are blown off by the blades, and the inner peripheral surface of the inclined drum 41 flies spirally, and the solder particles 2a having a large specific gravity fly farther. It is discharged from a recovery hole (not shown) provided near the front end opening of the inclined drum 41 to the external recovery duct 45 and dropped from the recovery duct 45 to the solder recovery container 51 for recovery. Further, the dross particles 3a in the inclined drum 41 are not discharged from the inclined drum 41 even when the rotating body 42 rotates, and when the rotating body 42 is stopped, the water vapor is accumulated at the bottom of the inclined drum 41 together with the cooled water. A discharge valve (not shown) is provided at the bottom of the inclined drum 41, and by opening the discharge valve, the dross particles 3a accumulated at the bottom of the inclined drum 41 are recovered together with water in the dross recovery container 52.

  When the above dross suction and solder recovery operations are continuously performed and all the dross in one solder tank 1 is sucked, the suction operation is stopped and the suction nozzle 21 is lifted from the solder tank 1 to The solder recovery apparatus 10 is moved to the solder tank. When the suction operation of the suction nozzle 21 is stopped in the state of FIG. 2, the check valve 35 rotates by its own weight to a substantially horizontal position to prevent the water droplets remaining in the nozzle from falling. Further, when the suction nozzle 21 is turned upward using the universal pipe 25, water droplets remaining in the nozzle flow to the universal pipe 25 and are removed from the suction nozzle 21.

  In addition, the solder collection | recovery apparatus of this invention is not limited to above-described embodiment, Of course, it can add various changes within the range which does not deviate from the summary of this invention.

It is a side view including a part omission and a partial section showing an embodiment of a solder recovery device concerning the present invention. It is a fragmentary sectional view for demonstrating operation | movement of the dross suction pulverization of the solder collection | recovery apparatus of FIG. (A) is the partial front view of the suction nozzle in FIG. 2, (B) is a bottom view.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solder tank 2 Molten solder 2a Solder grain 3 Dross 3a Dross grain 4 Floor 10 Solder collection | recovery apparatus 11 Main body 12 Wheel 20 Suction part 21 Suction nozzle 23 Air hole 24 Sensor 24a, 24b Electrode 25 Free pipe 26 Baffle plate 27 Vacuum generating means 28 Drive system 30 Spray section 31 Spray nozzle 32 Water supply pipe 35 Check valve 40 Separation section, centrifugal separator 41 Inclined drum 42 Rotating body 43 Electric motor 50 Collection section 51 Solder collection container 52 Dross collection container 60 Power supply unit for cordless operation

Claims (10)

  The solder-containing dross floating on the molten solder is vacuum-sucked with a suction nozzle, water is sprayed onto the dross immediately after suction, and the steam is exploded to smash the dross into dross grains and solder grains, and the solder grains are separated from the dross. A method for collecting solder, comprising collecting the solder.   2. The solder according to claim 1, wherein the tip of the suction nozzle is immersed in a liquid surface of the molten solder, and the dross in the nozzle tip is vacuum-sucked through an air hole formed in a side surface of the nozzle tip. Collection method.   A sensor is provided at the tip of the suction nozzle to detect the immersion depth of the tip into the molten solder surface, and the suction nozzle is moved horizontally relative to the molten solder based on the detection signal of the sensor. 3. The solder recovery method according to claim 2, wherein the dross is continuously vacuumed.   The solder recovery method according to claim 1, wherein the dross grains and the solder grains are centrifuged to separately collect the dross grains and the solder grains.   The solder recovery method according to claim 1, wherein the recovered solder particles are supplemented to the molten solder or other molten solder.   A suction part having a suction nozzle for vacuum suction of the dross floating on the molten solder from the opening of the tip, and a dross particle and solder by spraying water toward the dross sucked by the suction nozzle installed on the inner periphery of the tip of the suction nozzle A spray part having a spray nozzle for pulverizing into grains, a separation part for separating the dross grains and solder grains from a fluid flowing in the suction nozzle, and collecting the dross grains and solder grains separated by the separation part separately And a collecting unit for collecting the solder.   7. A check valve for preventing spray water from the spray nozzle from flowing back to the nozzle tip side is disposed between the suction nozzle tip of the suction nozzle tip and the spray nozzle. The solder recovery device described in 1.   The separating portion includes a bottomed inclined drum that accommodates the dross grains and the solder grains, and rotates at the bottom of the inclined drum so that the dross grains and the solder grains fly spirally along the inner peripheral surface of the inclined drum. A centrifugal separator having a rotating body to be run is provided, and the dross grains and the solder grains are separated by a difference in specific gravity while the dross grains and the solder grains are caused to fly on the inner peripheral surface of the inclined drum. 6. The solder recovery apparatus according to 6.   7. The solder recovery apparatus according to claim 6, wherein the suction unit, the spray unit, the separation unit, and the recovery unit are arranged in a cart-type main body that can be automatically or manually moved on the floor.   The solder recovery apparatus according to claim 9, wherein a power supply unit for cordless operation is provided in the main body.