JPH075323B2 - Sludge treatment method for ferric chloride waste liquid - Google Patents

Description

Detailed Description of the Invention

<Industrial field of application> The present invention relates to a sludge treatment method as a part of a regenerating process of ferric chloride waste liquid, that is, an etching waste liquid, for increasing the efficiency of precipitating a dissolved metal as sludge, Provided is one that can increase the concentration of ferrous chloride in the waste liquid and efficiently recycle the waste liquid. <Prior Art> The basic method of sludge treatment of ferric chloride waste liquid targeted by the present invention is to add ferric chloride waste liquid in which heavy metals other than iron are dissolved, at least metallic iron as a treating agent, This is a type in which ions are reduced to heavy metals and the precipitated heavy metals are removed as sludge from the waste liquid. As a conventional technique of the above-mentioned type, as shown in Japanese Patent Publication No. 61-44814, the treating agent is a lump of metallic iron alone, and the waste liquid contains nickel as a heavy metal other than iron, chromium, manganese, etc., There is one that effectively promotes the precipitation of heavy metals by keeping the waste liquid in a heated state and stirring it. In general, the ferric chloride solution is widely used as an etching solution for precisely processing a metal plate made of steel, copper, stainless steel, nickel alloy or the like, and is also used as an inorganic coagulant for sewage treatment. The corrosive power of the etching solution decreases as the number of treatments increases, and finally it becomes a waste liquid.However, since there are many pollution problems when the waste liquid is simply subjected to alkali neutralization treatment or the like, it is regenerated. Therefore, it is desirable to recycle more than once. Therefore, as a simpler treatment method, chlorine gas is blown into the waste liquid as it is, and divalent Fe in the waste liquid is trivalent.
It may be possible to oxidize Fe to regenerate the ferric chloride solution, but in the waste liquid, in addition to most of trivalent Fe and divalent Fe, Ni, Cr, which is eluted from the metal plate, Zn, Mn, Co, Cu, and other heavy metal ions are contained in large amounts, and it is speculated that these dissolved metal ions interfere with the oxidation reaction. Corrosion does not recover. Therefore, as in the prior art, first, the dissolved metal ions are reduced to metal by lumpy metallic iron to cause precipitation and precipitation, and the precipitated heavy metal is solid-liquid separated from the waste liquid as sludge,
By blowing a chlorine gas after obtaining a ferrous chloride solution containing few impurities, a ferric chloride solution having a high corrosive power can be regenerated. <Problems to be Solved by the Invention> However, in the above-mentioned conventional technique, the recovery of the corrosive force of the waste liquid is good as compared with the above-mentioned simple method, but as a practical problem, the reaction speed of the waste liquid and the treating agent is slow. However, it takes time to deposit heavy metals. Moreover, for example, the concentration of heavy metals in the generated sludge, for example, the concentration of nickel, is not very high, and even if it is attempted to recover and reuse heavy metals such as nickel from the sludge, the economic value of the obtained sludge Is low. An object of the present invention is to increase the processing reaction rate of waste liquid. <Means for Solving the Problem> The present inventor added metal iron to the etching waste liquid of the stainless steel plate, and in the step of precipitating a dissolved metal ion such as nickel ion in the waste liquid as a metal, in another waste liquid treatment. It was discovered that metal precipitation is promoted when the obtained sludge containing copper is mixed, and the present invention was completed based on this finding. That is, in the first invention, in the sludge treatment method of ferric chloride waste liquid as the basic method, the treating agent added to the ferric chloride waste liquid is metallic iron and metallic copper, It is characterized in that precipitation of heavy metals is promoted by mixing metallic copper as a component. The second invention is characterized in that, in the first invention, as the second component of the treating agent, sludge containing a large amount of metallic copper produced in the previous treatment is used in the next treatment instead of metallic copper. To do. Further, in the third invention, in the first invention, as a second component of the treating agent, metallic iron is added to a ferric chloride waste liquid in which a large amount of at least copper is dissolved as a heavy metal other than iron, instead of metallic copper. It is characterized in that sludge containing a large amount of metallic copper, which precipitates when added, is used. The ferric chloride waste liquid of the first to third inventions is, for example, a steel plate,
An etching waste liquid such as a stainless steel plate, a nickel alloy, and a copper plate, in which heavy metals such as nickel, chromium, lead, copper, manganese, and cobalt are dissolved in addition to iron. The reduction in the first to third inventions means that the addition of a treating agent results in substitution, adsorption, coprecipitation, or other reaction of dissolved metal ions, resulting in a metal. The method of adding the treatment agent may be to add two components of iron and copper to the waste liquid at the same time, or to add them separately with a slight time difference, and at the time of addition, heating, shaking, stirring as in the prior art. It does not matter if you do the following. The above-mentioned sludge refers to a precipitate in a broad sense including a precipitate of heavy metal that is reduced and precipitated, a copper component added in the previous treatment, and the like. <Operation> (1) Since the reaction mechanism when metallic copper is mixed is unknown, the operation of the first invention will be described phenomenologically using an etching waste liquid of a stainless steel plate as an example. In the etching waste liquid, ferrous iron, ferric iron, nickel,
Metal ions such as chromium are dissolved, but these are reduced to metallic nickel, metallic chromium, etc. by the addition of a treatment agent consisting of metallic iron and metallic copper (however, ferrous iron remains the same). . These deposited and precipitated metals are filtered as sludge by a filter press or the like and separated from the etching waste liquid to obtain a high-purity ferrous chloride solution. Although the sludge treatment completes the treatment process of the present invention, the waste liquid is practically regenerated through the treatment process described below. Chlorine gas is blown into the separated waste liquid containing few impurities to oxidize ferrous chloride to ferric chloride to regenerate the etching liquid. (2) In the second invention, when the first invention is applied to the ferric chloride waste liquor, the sludge generated as a result contains at least a large amount of metallic copper. This sludge is to be reused as a substitute for the metallic copper added in (1). (3) In the first invention, the second component of the ferric chloride waste liquid treating agent is metallic copper. However, in the third invention, as the second component, instead of metallic copper,
For example, it is intended to utilize sludge that precipitates and precipitates when metallic iron is added to an etching waste liquid of a copper plate. Therefore, when trying to regenerate the etching waste liquid of various material plates in an actual factory, according to the third aspect of the present invention,
The sludge generated by the treatment of the etching waste liquid of the copper plate can be used for the regeneration treatment of the etching waste liquid of the stainless steel plate. <Example> Hereinafter, an experimental example of the present invention will be shown by using a case where metallic iron alone is used as a treatment agent as a comparative example, and a change in the dissolved metal concentration when the addition ratio of copper was changed was examined.

[Experimental Example 1] 250 g of ferric chloride waste liquid obtained by etching a stainless steel plate
In addition, in order to prevent crystallization of ferrous chloride, 50 cc of water was added as a stock solution, and the stock solution was preheated to 80 ° C.,
Metal dissolved in the stock solution by adding a treating agent consisting of 30 g of metal iron cutting waste (that is, casting waste) and 18 g of copper powder to the stock solution (that is, preparing a processing solution containing approximately 5 wt% copper) The change with time of the ion concentration was measured by taking Ni, Cr, Cu, Co, and Cd ions as examples. The above measurement was carried out by boiling the undiluted solution containing the treating agent at 80-85
While keeping the liquid temperature at 0 ° C., the operation of heating for 10 minutes, taking out, and shaking for 1 minute was repeated, and the operation was performed every predetermined time. However, in Comparative Examples, using a solution obtained by adding only casting waste 30g to the stock solution, Ni, Cr in the same operation as the measurement method of the present invention
And various metal ion concentrations were measured. In addition, the measurement time starts from the time when the treatment agent is added. The results are shown in FIGS. 1 and 3, and the difference in nickel ion concentration between the present invention and the comparative example spreads over time, and after 3 hours, the present invention became 1/3 or less of the comparative example. Therefore, it can be seen that when metallic copper is added to the waste liquid as the second component of the treating agent, the concentration of dissolved metal ions is further reduced as compared with the case where metallic iron is added alone. This means that the concentration of the precipitated metal increases and the reduction reaction rate of the metal increases. Therefore, in the realistic regeneration treatment of the etching waste liquid in the factory, the treatment operation can be speeded up, and the concentration of metal contained in the generated sludge can be improved to enhance its economic value.

[Experimental Example 2] A precipitate obtained by removing the liquid phase component of ferrous chloride from the solution after the experiment of Experimental Example 1 (that is, the experimental solution after 3 hours from the addition of the treating agent) (Experimental Example) (Including metallic iron and metallic copper initially added in Example 1) was added to a stock solution (250 g of waste liquid + 50 cc of water) prepared to have the same composition as in Experimental Example 1, and heated in the same manner as in Experimental Example 1, The change with time of the concentration of each metal ion including nickel and chromium in the solution was measured. However, in the comparative example, the precipitate (containing metallic iron) obtained in the comparative example of Experimental Example 1 was added to the above stock solution and then heated. That is, in the second embodiment, the metal powder of Experimental Example 1 is replaced by the precipitate generated in the experiment. The results are shown in FIGS. 2 and 3, and it can be seen that the dissolved metal concentration can be effectively reduced even if a precipitate containing copper is used. For this reason, in the realistic recycling process of etching wastewater in factories, once copper metal is added and the recycling process is performed, the precipitate generated at that time is efficiently reused for the next recycling process. it can. In addition, the nickel ion concentration after 30 minutes is increasing rapidly,
It is speculated that the metallic nickel in the newly added precipitate is oxidized again into nickel ions by the ferric chloride in the stock solution.

[Experimental Example 3] The amount of copper added to the etching waste liquid was changed to examine the change over time of the dissolved Ni ion concentration in the waste liquid. That is, using Experimental Example 1 as a basic experimental example, the addition ratio of copper powder was changed to prepare copper-containing treatment liquids of 1, 3, 5, and 10 wt% respectively, and the first experiment was performed, and after addition of the treatment agent. The second experiment was conducted by increasing the shaking time of the stock solution from 1 minute to 2 minutes. Figures 4 and 5 show the results, and the copper concentration was 5 to 1w.
It can be seen that changing to t% does not significantly affect the Ni ion concentration. On the other hand, when the shaking time is increased from 1 minute to 2 minutes, the Ni ion concentration tends to slightly increase. Therefore, in the actual treatment, while suppressing the addition ratio of copper to a low level, a sufficient metal precipitation effect can be achieved, and
It can be inferred that the shaking operation does not have to be performed that long. <Effects of the Invention> (1) In the first to third inventions, since metallic copper is added as the second component of the treatment agent added to the ferric chloride waste liquid, metallic iron alone is used as can be seen from the above experimental results. As compared with the case of addition, the concentration of dissolved metal ions is further reduced, the concentration of precipitated metal is increased, and the reduction reaction rate of the metal is accelerated. For this reason, in a realistic regeneration treatment of the etching waste liquid in the factory, the regeneration treatment time can be shortened and the etching productivity can be improved. Further, since the metal concentration of the sludge to be generated is increased and the economic value thereof is improved, wasteful cost is not required for the disposal of the sludge. (2) In the second invention, since the sludge containing a large amount of metallic copper generated in the previous treatment is reused, the amount of copper added can be saved and the waste liquid can be regenerated more efficiently. (3) When the third invention is applied to an etching treatment waste liquid treatment of various material plates in an actual factory, sludge generated by the etching treatment of a copper plate can be used for the regeneration treatment of the etching waste liquid such as a stainless steel plate, and the waste liquid treatment can be performed. This sludge, which is the existing waste associated with it, can be actively utilized.

[Brief description of drawings]

FIG. 1 is a chart showing the time-dependent changes in the concentration of dissolved heavy metals in the waste liquid corresponding to Experimental Example 1, FIG. 2 is a view corresponding to FIG. 1 showing the results of Experimental Example 2, and FIG. 3 is a time-dependent change in the nickel ion concentration. FIG. 4 is a graph of nickel ion concentration showing the results of Experimental Example 3, and FIG. 5 is a graph showing the results of the first experiment corresponding to FIG.

Claims (3)

[Claims] 1. A ferric chloride waste liquor in which heavy metals other than iron are dissolved, at least metallic iron is added as a treating agent to reduce dissolved metal ions to heavy metals, and the precipitated heavy metals are removed as sludge from the waste liquor. In the sludge treatment method for ferric chloride waste liquid, the treating agent added to the ferric chloride waste liquid is metallic iron and metallic copper, and by mixing metallic copper as the second component of the treating agent, precipitation of heavy metals Sludge treatment method for ferric chloride waste liquor characterized by accelerating 2. The method for treating sludge of a ferric chloride waste liquid according to claim 1, wherein the second component of the treating agent is sludge containing a large amount of metallic copper produced in the previous treatment, instead of metallic copper. , Sludge treatment method for ferric chloride waste liquid, characterized by being used for the next treatment 3. The sludge treatment method for ferric chloride waste liquor according to claim 1, wherein, as the second component of the treating agent, at least a large amount of copper is dissolved as a heavy metal other than iron, instead of metallic copper. Sludge treatment method for ferric chloride waste liquid, characterized in that sludge containing a large amount of metallic copper, which precipitates when metallic iron is added to the ferric iron waste liquid, is used