JP2010189747A - METHOD FOR PRODUCING HIGH-GRADE RECYCLED Ni SLUDGE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a high-grade recycled Ni sludge from which Ni can be economically recovered, by separating Ni sludge from a washing water originating in a Ni-plating process. <P>SOLUTION: This production method includes: providing areas in which a plurality of plating lines that are formed of a Ni-plating process or a composite process of Ni plating and other metal plating are arranged in parallel; also providing a waste water treatment line for producing sludge from the washing water in the Ni-plating process in the same area or in a place adjacent to the same area; pouring an organic polymer flocculant into a flocculation tank; settling the agglomerate in a settling tank to separate it; extracting the settled sludge from the bottom; returning the sludge back to a pH control tank at least one time to make the sludge recycled; extracting the settled sludge again and sending it to a sludge tank in the next concentration step; and subsequently extracting the sludge while storing it in the sludge tank and sending it to a hydro extractor to obtain the sludge. The sludge becomes a valuable that contains a high concentration of Ni, from which Ni can be economically recovered by a processor. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  In this invention, Ni sludge (sludge) is separated from the Ni washing water generated in the Ni plating work process, and Ni sludge having a concentration high enough to be a valuable material that can be economically recovered by the processing company is obtained. The present invention relates to a method for producing high quality Ni recycled sludge.

  Plating has many work processes until one product is finished, and water washing is always performed between each work process, and a water washing tank is installed between the plating tank and the plating tank. Since the washing water soiled by this washing contains acid, alkali, heavy metal, and other harmful pollution control substances, all the waste water must be treated before being discharged. For this reason, the plating line is also provided with a sludge waste water treatment line for the plating washing water. Sludge containing these metals and the like is generated in the wastewater treatment, but in the case of Ni, since the content is small, conventionally, this has been handed over to a contractor for landfill treatment.

  However, since the plating solution contains cyanide compounds of valuable metals such as Ni, copper, zinc, gold and silver, proposals have been made to recover these valuable metals (Patent Document 1). According to the method, in a method for recovering a valuable metal from a cyanide-containing liquid in which a cyanide compound of at least one kind of valuable metal selected from the group consisting of Ni, copper, zinc, gold and silver is dissolved, Hypochlorite is continuously added to the containing liquid under conditions of an alkaline temperature range from 60 ° C. to less than the boiling point, and silver of the valuable metals is precipitated as a chloride, and Ni, copper and zinc are oxides or It is precipitated as a hydroxide, and gold is dissolved in a solution as a chloroaurate.

JP 2003-147444 A

  In the invention of the above-mentioned Patent Document 1, since the metal is deposited from the washing water, it is difficult to adopt as a special facility and work. Therefore, recycling was pursued to extract Ni from the sludge. However, as an obstacle, it was considered that Ni was dissolved in alkaline water in the reduction process for separating the sludge from the Ni washing water and simultaneously washed away. Further, conventionally, an inorganic flocculant has been used in the flocculant, but this is not only expensive, but it has also been found that the dewaterability is poor and it is ultimately not suitable for the concentration of Ni.

  This invention is based on the above-mentioned knowledge, and sludge is a relatively expensive useful metal for treating washing water derived from Ni plating, although it is a common equipment and operation in a plating factory. Therefore, an object of the present invention is to provide a method for producing high-grade Ni recycled sludge that can produce a replacement value enough to allow a contractor to collect it for a fee as a valuable resource.

  In order to solve the above problems, the present invention provides an area in which a plurality of plating lines composed of a Ni plating process or a combined process of Ni plating and other metal plating are provided in parallel, and is adjacent to the same area or the same area. In addition, a Ni-plated flush water sludge drainage treatment line is provided, and for Ni-plated flush water, the flush water is separately collected from each Ni plating line and stored in a dedicated Ni rinse water storage tank. Introduce caustic soda in the Ni washing water supplied from the Ni washing water storage tank in the reduction tank, then adjust the pH to alkali in the pH adjustment tank to make hydroxide, and in the coagulation tank use organic polymer flocculant The aggregate is settled and separated in a sedimentation tank, and the settled sludge is withdrawn from the bottom, and returned to the pH adjustment tank at least once and recycled. The product is passed again through the sedimentation tank, and the water is allowed to overflow. The sludge that has settled again is drawn into the sludge tank of the next concentration step, and then withdrawn to the dehydrator while storing in the sludge tank. The present invention provides a method for producing high-grade Ni recycled sludge, characterized in that sludge is obtained as a valuable material having a high Ni concentration of 20% to 100% that can be purchased because Ni can be recovered.

  According to the above configuration, the Ni washing water is adjusted to an alkali, but Ni is not dissolved in the washing water and is not washed away at the same time, and the organic polymer has a good dehydrating property in the flocculant. By using the flocculant, the concentration of Ni was reliably performed.

  More specifically, in the above-described wastewater treatment line, the washing water in the raw water tank is raised to pH 8 to 12 by injection of caustic soda in the reduction tank, stirred, and adjusted to about pH 10 in the pH adjustment tank.

  As described above, according to the present invention, in order to treat washing water derived from Ni plating, it becomes a common equipment and operation in a plating factory, and hydroxide discharged from a plating line is a plating species. Since it is collected separately, it is easy to ascertain the metal content in acid / alkaline wastewater and ensure proper wastewater treatment, and eventually separate into harmful sludge and harmless effluent water. The sludge contains Ni as a relatively expensive useful metal so that it can be recovered economically, allowing the contractor to pick it up as a valuable resource for a fee, and acquiring the exchange value can rationally reduce the production cost. There is an excellent effect.

It is a flowchart of the Ni washing water collection | recovery process which shows the some plating line which concerns on this invention in parallel. FIG. 2 is a flow diagram showing a high-grade Ni recycling process for separating the wash water taken in the process of FIG. 1 from discharged water and sludge. It is a flowchart which shows the high quality Ni recycling process as another Example. It is a flowchart which shows the high quality Ni recycling process as another Example. It is a flowchart which shows the high quality Ni recycling process as other Example.

  Hereinafter, embodiments of the present invention will be described in detail.

  In the plating factory, there are many plating lines, and each plating line is often different in the type of plating by plating several metals on top of each other, but among the plating, Ni is gold and silver Since it is a highly recyclable metal, it was aimed to recover Ni from the washing water. As a premise thereof, Ni-plated flushing water is collected from each plating line (see symbol 2 in FIG. 1).

  Starting from the Ni washing water storage tank 1 that collects and collects Ni washing water from each plating line, a high-grade Ni recycling process is started. In this process, Ni sludge is obtained through the Ni washing water reduction process, pH adjustment process, agglomeration process, sedimentation process, and concentration process, which contains harmful substances. It will be released pollution-free without being caught. It has been confirmed that when the Ni content of the sludge is 20% or more, the processor can economically recover Ni.

  The reduction tank 2 and the pH adjustment tank 3 which perform the reduction process and the pH adjustment process after the Ni washing water dedicated storage tank 1 are equipped with a stirrer, and inject an acid and a reducing agent in conjunction with the pH meter and the ORP meter. It is a mechanism to do. Sulfuric acid and hydrochloric acid are used as the acid, but sulfuric acid that is inexpensive is most suitable. Caustic soda (NaOH) or lime milk is used for alkali. NaOH has the advantage that it is easy to handle as a solution, the amount of sludge produced is small (Ni concentration becomes high on the contrary), and pH adjustment is easy. On the other hand, depending on the drainage, sludge is light and sedimentation and dewaterability may be poor.

  Since slaked lime is powder and does not dissolve in water, it is used as lime milk (about 10%) with constant stirring. The advantage of using slaked lime is that the sludge has good sedimentation and dewaterability, and fluorine, phosphorus and COD removal is good. Also, the price is cheap. Disadvantage is poor handling. Poor reactivity and difficult to control pH. Increases sludge production.

  In the agglomeration tank 4 forming the agglomeration step, a floc is generated by adding and aggregating the flocculant to the wastewater in which heavy metal oxides and other precipitates are produced by adjusting the pH, and the effect of separating the precipitate in the next sedimentation tank 5 is produced. To increase. Flocculants for this purpose are mainly classified as inorganic and organic, and low and high molecular. Inorganic flocculants include polyvalent metal salts such as aluminum sulfate, polyaluminum chloride, and ferric sulfate. However, in the present invention, an organic flocculant (synthetic polymer flocculant) is used, and this is mainly derived from polyacrylamide as a main component. Organic polymer flocculants are classified into powder and jelly types, and usually dissolve in water to about 0.2%.

  The sedimentation tank 5 is a tank that separates precipitates such as agglomerated heavy metal hydroxide, and the effect of sediment removal is determined by the water area load Q / A (water amount / sedimentation tank area), and the smaller the value, the higher the separation effect. The upper water of the settling tank 5 is neutralized by the addition of alkali or acid in the neutralization tank 6 and discharged, and the settled sludge passes through the dewatering machine 10 from the sludge tank 9 and is a valuable material containing 20% to 100% Ni. As recycled.

  In one area of the factory, the Au / Ni process (first line), the Au / Ni / Sn process (second line), and the Ni / Sn process (third line) are shown in parallel. Yes. Among them, a circle symbol 2 is an arrow showing a state in which the Ni washing water is collected from each line. Here, the wash water containing Ni is collected in the Ni wash water storage tank 1 of the sludge wastewater treatment line (FIG. 2). In addition, although work time is described in FIG. 2, the time required is shown roughly.

  In the processing line, following the flush water storage tank 1, a reduction tank 2, a pH adjustment tank 3, a flocculation tank 4, a settling tank 5, a neutralization tank 6, and a discharge tank 7 are connected in series so as to correspond to the above-described steps. The sludge tank 9 of the concentration process is arranged in parallel to the settling tank 5, and the dewatering machine 10 follows the sludge tank 9. Next, the work process will be described.

(1) Recovery process dedicated to Ni washing water As described above, only Ni washing water is collected from each plating line and collected in the Ni washing water storage tank 1. Then, the following processing is performed in the same area.
(2) Reduction process When flush water is sent from the treated water storage tank of the Ni washing water storage tank 1 to the reduction tank 2, in the reduction tank 2, as indicated by an arrow 12, sodium hydroxide is first injected to adjust the pH to 8-12. Then, the mixture is stirred.
(3) pH adjustment process The washing water sent from the reduction tank 2 to the pH adjustment tank 3 is adjusted to about pH 10 by adding sodium hydroxide / sulfuric acid as indicated by an arrow 13. This produces Ni and heavy metal hydroxides.
(4) Aggregation step When the treated water in which the hydroxide is suspended is sent to the agglomeration tank 4, about 0.1% of an organic polymer flocculant is injected into the washing water (arrow 14), Then, it is sent to the next settling tank 5. When the organic polymer flocculant is used, the Ni sludge grains are larger than those of the inorganic system, so that the dewaterability is improved, and a high-quality sludge having a low water content and a high Ni concentration is easily recycled.
(5) Sedimentation step The sedimentation tank 5 is allowed to settle and separate by allowing it to stand. The water is allowed to overflow, and the settled sludge is drawn from below. Hazardous substances such as heavy metals are contained in sludge, so the overflowed water is neutralized by adding sodium hydroxide / sulfuric acid in the neutralization tank 6 (arrow 15) without touching the regulations. It is released. The extracted sludge is recycled back to the pH adjusting tank at least once before being transferred to the sludge tank 9 in the next concentration step, and the condensate thus concentrated is again settled and separated through the settling tank. Pulled out from below. Thus, the Ni concentrated sludge drawn again is transferred to the sludge tank 9 of the next concentration step (arrow 16).
(6) Concentration step In the sludge tank 9, it is stored and concentrated by being submerged by gravity. It is pulled out by the dehydrator 10 (arrow 17) where water is squeezed. The concentrated sludge contained 53% as Ni.
(7) Unloading process If 20% or more of Ni is contained, the processing company can extract Ni economically, so it is bought and transported as a valuable resource (arrow 18), and the plating company obtains the price. As a result, this contributes to a gradual reduction in the production cost of plating.

  In addition, in the said Example, it can replace with the reduction tank 2 of a reduction | restoration process, and can use RO apparatus (membrane processing apparatus) (FIG. 3, FIG. 5). RO device is a reverse osmosis device that uses a semi-permeable membrane that permeates water but does not permeate ions or molecules dissolved in water, and applies a pressure higher than the osmotic pressure of the solution to the aqueous solution to separate it into a solvent and a solution. It is. By using this RO apparatus instead of the reduction tank 2, the solvent water is utilized for recycling, the Ni solution is concentrated, and transferred to the pH adjustment tank 3 of the next step.

  Moreover, in the said Example, it can replace with the flocculation tank 4 and the sedimentation tank 5 which comprise a flocculation process and a sedimentation process, and can also use MF apparatus (microfiltration apparatus) which is a kind of membrane processing apparatus (FIG. 3). FIG. 4). The MF device is a device that performs filtration using a hydrophilic polysulfone system having a separation performance of 0.1 microns as a microfiltration membrane, as a microfiltration membrane. Suspensions (SS), bacteria, etc. in the raw water are filtered, and only the filtered water is taken out from the hollow fiber membrane. Water from this device is used for recycling, and Ni liquid is drawn out to the sludge tank 9 which is a concentration process.

  Needless to say, both the RO device and the MF device as alternative devices may be simultaneously incorporated in the above-described embodiment process (FIG. 3). Moreover, like the said Example, before shifting to the sludge tank 9 of a concentration process, it is recycled to the pH adjustment tank 3 of a previous process at least once, and is high-quality (Ni content 20%-as a final product). 100%) Ni recycled sludge can be obtained.

DESCRIPTION OF SYMBOLS 1 Ni washing water exclusive storage tank 2 Reduction tank 3 pH adjustment tank 4 Coagulation tank 5 Settling tank 6 Neutralization tank 7 Discharge tank 9 Sludge tank 10 Dehydrator 12 Sodium hydroxide 13 Sodium hydroxide / sulfuric acid 14 Polymer flocculant 15 Hydroxide Sodium / sulfuric acid 16 Sludge 17 Sludge 18 High-grade Ni recycled sludge

Claims (4)

  A plurality of plating lines consisting of Ni plating process or a combination process of Ni plating and other metal plating are provided in parallel, and a sludge waste water treatment line for Ni plating washing water is provided adjacent to the area or the same area. For Ni-plated flush water, the flush water is separately collected from each Ni-plating line and stored in a dedicated Ni-wash water storage tank. In the drainage treatment line, the Ni-wash water supplied from the Ni-wash water dedicated tank is used. Caustic soda is injected in the reduction tank, then the pH is adjusted to alkali in the pH adjustment tank to produce hydroxide, the organic polymer flocculant is injected in the coagulation tank, and the aggregate is settled and separated in the settling tank. The settled sludge is withdrawn from below, recycled at least once to the pH adjustment tank, recycled, and the concentrated condensate passes through the settling tank again. The sludge that settled again is pulled out to the sludge tank of the next concentration process, and then pulled out to the dehydrator while being stored in the sludge tank. A method for producing high-grade Ni recycled sludge, characterized in that sludge is obtained as a valuable material having a high Ni concentration of -100%.   2. The waste water treatment line according to claim 1, wherein the washing water in the raw water tank is raised to pH 8-12 by injection of caustic soda in the reduction tank, stirred, and adjusted to about pH 10 in the pH adjustment tank. Manufacturing method of high quality Ni recycled sludge.   2. The method for producing high-grade Ni recycled sludge according to claim 1, wherein the refining tank is replaced with a washing water storage tank and transferred to a next pH adjusting tank through an RO device.   It changed to said coagulation tank and sedimentation tank, It comprised so that it might transfer to the next neutralization tank and sludge tank (concentration process) via a MF apparatus from a pH adjustment tank. The manufacturing method of high-grade Ni recycling sludge as described.

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