JP6757922B1 - Metal recovery method from sludge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a means capable of recovering zinc and a predetermined easily ionized metal from sludge containing zinc or a zinc compound and an easily ionized metal or a compound thereof at a low cost by a simple process and an apparatus. To do. SOLUTION: A metal recovery device S includes a potassium / sodium content removal device 1, a calcium content recovery device 2, a calcium content removal device 3, a magnesium content recovery device 4, a magnesium content removal device 5, and an aluminum content recovery device. A device 6, an aluminum component removing device 7, and a zinc content recovering device 8 are provided. The metal recovery device S chlorides calcium, magnesium, aluminum, and zinc from sludge containing zinc or its compound and potassium, calcium, sodium, magnesium, aluminum, or these compounds, which have a higher ionization tendency than zinc. Collect in the form of an aqueous solution. [Selection diagram] Fig. 1

Description

In the present invention, an easily ionized metal is prepared in the form of a chloride from a sludge containing a poorly water-soluble compound of a metal having a higher ionization tendency than zinc (hereinafter referred to as "easily ionized metal") and a poorly water-soluble zinc compound. It relates to a metal recovery method in which zinc is recovered in the form of zinc chloride as well as recovered.

In general, sludge or waste generated at business establishments involved in iron making, non-ferrous metal manufacturing, metal plating, inorganic chemical manufacturing, ceramics, printing, etc. contains various metals or compounds thereof. Since some of the metals or their compounds contained in such sludge or waste have high value as resources, various methods for recovering a specific metal or its compound from the sludge or waste have been proposed. There is.

In particular, sludge or waste generated at business establishments related to phosphoric acid production, zinc chrome plating, hot dip galvanizing, etc. contains a large amount of zinc or its compounds, which have high value as a resource, so such sludge or waste. Various methods for recovering zinc or zinc compounds from waste products have been proposed (see, for example, Patent Documents 1 to 3).

JP-A-59-88319 JP-A-61-158818 JP-A-2002-121626

In the zinc recovery method disclosed in Patent Documents 1 and 2, metallic zinc is used to recover zinc from zinc-containing substances (waste), so that high-purity zinc compounds can be recovered to recover relatively low-purity zinc compounds. There is a problem that metallic zinc must be consumed, which diminishes the economic effect of zinc recovery. Further, since ammonia is used for elution of zinc from the zinc-containing material and then the ammonia is recovered and recycled, there is a problem that a complicated device for circulating ammonia is required. On the other hand, the method for recovering a zinc compound from plating sludge disclosed in Patent Document 3 requires a large amount of ethanol for crystallization of the zinc compound, and therefore has a problem that the cost of recovering zinc is very high. Further, the zinc recovery method disclosed in Patent Documents 1 to 3 has a problem that a metal other than zinc, for example, an easily ionized metal or a compound thereof cannot be recovered.

The present invention has been made to solve the above-mentioned conventional problems, and from sludge containing zinc or a zinc compound and an easily ionized metal or a compound thereof at low cost by a relatively simple process or apparatus. The problem to be solved is to provide a means for recovering zinc or a compound thereof and a predetermined easily ionized metal or compound thereof.

The metal recovery method according to the first aspect of the present invention, which has been made to solve the above problems, is a poorly water-soluble easily ionized metal compound which is a compound of an easily ionized metal (a metal having a higher ionization tendency than zinc) and a poorly water-soluble metal compound. This is for recovering an easily ionized metal in the form of chloride and zinc in the form of zinc chloride from sludge containing a sex zinc compound. Examples of the recoverable easily ionized metal include barium (Ba), calcium (Ca), magnesium (Mg), aluminum (Al), titanium (Ti), manganese (Mn) and the like.

The metal recovery method according to the first aspect of the invention has the following steps.
(1) First step of recovering the easily ionized metal (2) Second step of removing the residual easily ionized metal compound (3) Third step of recovering zinc

The first step has the following steps.
・ First hydrochloric acid addition step ・ First filtration step ・ Easy ionized metal recovery step

In the first hydrochloric acid addition step, the amount of water and the equivalent amount of the easily ionized metal compound in the cake is smaller than the equivalent amount (for example, of the equivalent amount) to the cake generated by filtering the sludge containing the poorly water-soluble easily ionized metal compound and the zinc compound. 85-95%) of hydrochloric acid is added to change (chemically change) a part of the easily ionized metal compound into an easily ionized metal chloride and dissolve it in water to dissolve the easily ionized metal chloride and the easily ionized metal compound (chloride). A first slurry containing (other than the substance) and a zinc compound is produced. In the first filtration step, the first slurry is filtered to produce a first filtrate containing an easily ionized metal chloride and a first cake containing an easily ionized metal compound (other than chloride) and a zinc compound. In the easily ionized metal recovery step, the first filtrate is heated to vaporize the water content to produce an easily ionized metal chloride or a concentrated easily ionized metal chloride aqueous solution.

The second step has the following steps.
・ Second hydrochloric acid addition step ・ Second filtration step

In the second hydrochloric acid addition step, water and hydrochloric acid in an amount larger than the equivalent amount (for example, 105 to 110% of the equivalent amount) with respect to the poorly water-soluble easily ionized metal compound in the first cake are added to the first cake to facilitate the addition. The ionized metal compound is changed to easily ionized metal chloride and dissolved in water to produce a second slurry containing the easily ionized metal chloride and the zinc compound. In the second filtration step, the second slurry is filtered to produce a second filtrate containing an easily ionized metal chloride and a second cake containing a poorly water-soluble zinc compound.

The third step has the following steps.
・ Third hydrochloric acid addition step ・ Third filtration step ・ Zinc recovery step

In the third hydrochloric acid addition step, water and hydrochloric acid equal to or more than the equivalent amount (for example, 100 to 120% of the equivalent amount) of the poorly water-soluble zinc compound in the second cake are added to the second cake to chloride the zinc compound. It is converted to zinc and dissolved in water to produce a third slurry containing zinc chloride. In the third filtration step, the third slurry is filtered to produce a third filtrate containing zinc chloride and a third cake. In the zinc recovery step, zinc chloride or a concentrated zinc chloride aqueous solution is produced by heating the third filtrate to vaporize the water content.

The metal recovery method according to the second aspect of the present invention comprises sludge containing n kinds (any integer of n: 2 to 6) of poorly water-soluble easily ionized metal compounds and containing poorly water-soluble zinc compounds. The purpose is to recover each easily ionized metal in the form of chloride and zinc in the form of zinc chloride. Here, the ionization tendency of each easily ionized metal constituting the first to nth easily ionized metal compounds decreases in the order of the first to nth easily ionized metals.

The metal recovery method according to the second aspect of the present invention has the following steps. However, when n is 2, there are no "(3) step (group) for recovering the k-th easily ionized metal" and "(4) step (group) for removing the remaining k-easy ionized metal compound". ..
(1) Step of recovering the first easily ionized metal (2) Step of removing the first easily ionized metal compound remaining in the cake (3) Step of recovering the kth easily ionized metal (group) (k: 2- (An integer of any of (n-1))
(4) Steps (group) for removing the k-th easily ionized metal compound remaining in the cake.
(5) Step of recovering the nth easily ionized metal (6) Step of removing the nth easily ionized metal compound remaining in the cake (7) Step of recovering zinc

The step of recovering the first easily ionized metal has the following steps.
・ 1st hydrochloric acid addition step ・ 1st filtration step ・ 1st easy ionized metal recovery step

In the first hydrochloric acid addition step, water and the first easy ionization in the cake were formed by filtering sludge containing the poorly water-soluble first to nth easily ionized metal compounds and the poorly water-soluble zinc compound. A smaller amount (for example, 85 to 95% of the equivalent amount) of hydrochloric acid than the equivalent amount of the metal compound is added to change (chemically change) a part of the first easily ionized metal compound into a water-soluble first easily ionized metal chloride. To produce a first slurry containing the first easily ionized metal chloride, the first to nth easily ionized metal compounds (other than chloride), and a zinc compound. In the first filtration step, the first slurry is filtered to form a first filtrate containing a first easily ionized metal chloride and a first cake containing the first to nth easily ionized metal compounds (other than chloride) and a zinc compound. To generate. In the first easy ionized metal recovery step, the first filtrate is heated to vaporize the water content to produce a first easy ionized metal chloride solution or a concentrated first easy ionized metal chloride aqueous solution.

The step of removing the first easily ionized metal compound remaining in the cake has the following steps.
・ Second hydrochloric acid addition step ・ Second filtration step

In the second hydrochloric acid addition step, water and hydrochloric acid in an amount larger than the equivalent amount (for example, 105 to 110% of the equivalent amount) with respect to the poorly water-soluble first easily ionized metal compound in the first cake are added to the first cake. , The first easily ionized metal compound is changed to the first easily ionized metal chloride and dissolved in water, and the first easily ionized metal chloride, the second to nth easily ionized metal compounds, and the zinc compound are contained. 2 Generate a slurry. In the second filtration step, the second slurry is filtered to produce a second filtrate containing the first easily ionized metal chloride and a second cake containing the second to nth easily ionized metal compounds and the zinc compound.

The step (in the case of n = 3) or the step group (in the case of n = 4 to 6) for recovering the k-th easily ionized metal is carried out while increasing k by 1 from 2 to (n-1) (n−). 2) Consists of steps or groups of steps. However, when n is 2, this step does not exist. Each step constituting this step or step group has the following steps.
・ No. (2k-1) hydrochloric acid addition step ・ No. (2k-1) filtration step ・ No. k easy ionized metal recovery step

In the third (2k-1) hydrochloric acid addition step (third, ... third (2n-3) hydrochloric acid addition step), the poorly water-soluble k to nth easy compounds produced in the (2k-2) filtration step. A smaller amount (eg, 85-95% of the equivalent) of water and the k-easy ionized metal compound in the (2k-2) cake in the second (2k-2) cake containing the ionized metal compound and the zinc compound. A part of the k-easy ionized metal compound is changed to a water-soluble k-easy ionized metal chloride and dissolved in water by adding hydrochloric acid, and the k-easy ionized metal chloride and the k-th easy ionized metal chloride are added. A second (2k-1) slurry containing an ionized metal compound (other than chloride) and a zinc compound is produced. In the second (2k-1) filtration step, the (2k-1) slurry is filtered, and the (2k-1) filtrate containing the kth easily ionized metal chloride and the kth to nth easily ionized metal compounds (chlorides) are filtered. (Non-material) and a second (2k-1) cake containing a zinc compound are produced. In the k-easy ionized metal recovery step, the k-easy ionized metal chloride solution or the concentrated k-easy ionized metal chloride aqueous solution is produced by heating the (2k-1) filtrate to vaporize the water content.

In the step (in the case of n = 3) or the step group (in the case of n = 4 to 6) for removing the kth easily ionized metal compound remaining in the cake, k is increased by 1 from 2 to (n-1). Consists of (n-2) steps or groups of steps performed while However, when n is 2, this step does not exist. Each step constituting this step or step group has the following steps.
・ 2k hydrochloric acid addition step ・ 2k filtration step

In the 2k hydrochloric acid addition step (4th, ... 4th (2n-2) hydrochloric acid addition step), water is added to the (2k-1) cake, and the poorly water-soluble first in the (2k-1) cake. A larger amount (for example, 105-110% of the equivalent amount) of hydrochloric acid than the equivalent amount with respect to the k-easy ionized metal compound is added to change the k-easy ionized metal compound into the k-easy ionized metal chloride and dissolved in water. A second k slurry containing the k-easily ionized metal chloride, the (k + 1) -nth easily ionized metal compounds, and the zinc compound is produced. In the second k filtration step, the second k slurry is filtered to produce a second k filtrate containing the kth easily ionized metal chloride and a second k cake containing the (k + 1) to nth easily ionized metal compounds and the zinc compound. ..

The step of recovering the n-th easily ionized metal has the following steps.
・ No. (2n-1) hydrochloric acid addition step ・ No. (2n-1) filtration step ・ Nth easy ionized metal recovery step

In the second (2n-1) hydrochloric acid addition step, the second (2n-2) cake containing the poorly water-soluble nth easily ionized metal compound and the poorly water-soluble zinc compound produced in the second (2n-2) filtration step was formed. , Water and a smaller amount (eg, 85-95% of the equivalent) of hydrochloric acid than the equivalent of the n-easy ionized metal compound in the (2n-2) cake was added to add a portion of the n-easy ionized metal compound. It is converted into a water-soluble n-easy ionized metal chloride and dissolved in water, and contains the n-easy ionized metal chloride, the n-easy ionized metal compound (other than chloride), and a zinc compound (2n-). 1) Generate a slurry. In the second (2n-1) filtration step, the (2n-1) slurry is filtered, and the (2n-1) filtrate containing the nth easily ionized metal chloride and the nth easily ionized metal compound (other than chloride) are used. And a second (2n-1) cake containing a zinc compound. In the n-easy ionized metal recovery step, the n-easy ionized metal chloride solution or the concentrated n-easy ionized metal chloride aqueous solution is produced by heating the (2n-1) filtrate to vaporize the water content.

The step of removing the nth easily ionized metal compound remaining in the cake has the following steps.
・ 2n hydrochloric acid addition step ・ 2n filtration step

In the second n hydrochloric acid addition step, the amount (for example, equivalent of 105-110) of water and the poorly water-soluble n-easy ionized metal compound in the second (2n-1) cake is larger than the equivalent of the second (2n-1) cake. %) Hydrochloric acid was added to change the n-easy ionized metal compound into n-easy ionized metal chloride and dissolved in water, and the n-easy ionized metal chloride and the zinc compound (other than zinc chloride) were separated. A second n slurry containing is produced. In the second n filtration step, the second n slurry is filtered to produce a second n filtrate containing the nth easily ionized metal chloride and a second n cake containing a zinc compound (other than zinc chloride).

The step of recovering zinc has the following steps.
・ No. (2n + 1) hydrochloric acid addition step ・ No. (2n + 1) filtration step ・ Zinc recovery step

In the second (2n + 1) hydrochloric acid addition step, water and hydrochloric acid equal to or more than the equivalent amount (for example, 100 to 120% of the equivalent amount) of the poorly water-soluble zinc compound in the second n-cake are added to the second n-cake containing the zinc compound. Then, the zinc compound is changed to zinc chloride and dissolved in water to produce a (2n + 1) th slurry containing zinc chloride. In the second (2n + 1) filtration step, the second (2n + 1) slurry is filtered to produce a second (2n + 1) filtrate containing zinc chloride and a second (2n + 1) cake. In the zinc recovery step, the (2n + 1) filtrate is heated to vaporize the water content to produce zinc chloride or a concentrated zinc chloride aqueous solution.

According to the metal recovery method according to the present invention, zinc and a predetermined easily ionized metal can be obtained from sludge containing zinc or a zinc compound and an easily ionized metal or a compound thereof at low cost by a relatively simple process or apparatus. , Can be recovered in the form of zinc chloride and easily ionized metal chloride, respectively.

It is a system block diagram of the metal recovery apparatus for carrying out the metal recovery method which concerns on this invention. It is a schematic elevation view of the apparatus which removes potassium and sodium from sludge which constitute the metal recovery apparatus shown in FIG. It is a schematic elevation view of the apparatus which recovers calcium, magnesium, aluminum or zinc as a chloride aqueous solution, which constitutes the metal recovery apparatus shown in FIG. FIG. 5 is a schematic elevational view of an apparatus for removing a poorly water-soluble easily ionized metal compound (compound of calcium, magnesium or aluminum) remaining in a cake constituting the metal recovery apparatus shown in FIG. 1.

Hereinafter, embodiments of the present invention will be specifically described with reference to the accompanying drawings. This embodiment corresponds to the case where n is 3 and the first to third easily ionized metals are calcium, magnesium and aluminum, respectively, in the metal recovery method according to the second aspect of the present invention. .. The sludge in this embodiment is sludge generated in business establishments related to, for example, iron making, non-ferrous metal manufacturing, metal plating, inorganic chemical manufacturing, ceramics, printing, etc., and is the first to third easily ionized metals (calcium, magnesium, etc.). In addition to aluminum) ions or compounds, it also contains potassium and sodium (easily ionized metal) ions or compounds. Most of the compounds of the first to third easily ionized metals in sludge are poorly water-soluble (almost water-insoluble), but these chlorides are water-soluble. On the other hand, all potassium and sodium compounds are water-soluble.

FIG. 1 shows the overall configuration of the metal recovery device S according to the embodiment of the present invention. This metal recovery device S includes zinc ions or compounds (hereinafter referred to as "zinc content") and potassium, calcium, sodium, magnesium and aluminum ions or compounds (hereinafter, "potassium content", respectively) having a higher ionization tendency than zinc. , "Calcium", "Sodium", "Magnesium" and "Aluminum"), calcium, magnesium, aluminum and zinc in the form of their respective chloride aqueous solutions (concentrates). It is to be collected at. In the metal recovery device S, the aqueous solution (mixture) containing potassium and sodium is not recovered and is disposed of or discarded because the separation of potassium and sodium is complicated.

As shown in FIG. 1, the metal recovery device S is referred to as a potassium / sodium content removing device 1 (hereinafter referred to as “K / Na content removing device 1”) and a calcium content recovery device 2 (hereinafter referred to as “Ca recovery device 2”). ), Residual calcium content removing device 3 (hereinafter referred to as "Ca removing device 3"), magnesium content recovery device 4 (hereinafter referred to as "Mg recovery device 4"), and residual magnesium content removing device 5 (hereinafter referred to as "Mg"). Removal device 5 "), aluminum recovery device 6 (hereinafter referred to as" Al recovery device 6 "), residual aluminum removal device 7 (hereinafter referred to as" Al removal device 7 "), and zinc recovery device. 8 (hereinafter referred to as “Zn recovery device 8”) is provided.

The K / Na removing device 1 removes potassium and sodium from the sludge introduced into the metal recovery device S. The Ca recovery device 2 recovers calcium from the cake generated by the K / Na removing device 1 in the form of an aqueous calcium chloride solution. The Ca removing device 3 removes calcium compounds (other than calcium chloride) remaining in the cake generated by the Ca recovery device 2. The Mg recovery device 4 recovers magnesium in the form of an aqueous magnesium chloride solution from the cake generated by the Ca removal device 3. The Mg removing device 5 removes magnesium compounds (other than magnesium chloride) remaining in the cake generated by the Mg recovery device 4. The Al recovery device 6 recovers aluminum from the cake generated by the Mg removal device 5 in the form of an aluminum chloride aqueous solution. The Al removing device 7 removes aluminum compounds (other than aluminum chloride) remaining in the cake produced by the Al recovery device 6. The Zn recovery device 8 recovers zinc in the form of an aqueous zinc chloride solution from the cake generated by the Al removal device 7.

For the Ca recovery device 2, the calcium chloride aqueous solution produced by the Ca recovery device 2 is heated with steam or a heat medium to vaporize and concentrate the water, and the water vapor generated by the concentrator 10. A condenser 11 for cooling and condensing the mixture with cooling water and a storage tank 12 for storing the calcium chloride aqueous solution concentrated by the concentrator 10 are provided. A part or all of the condensed water (distilled water) of the condenser 11 is returned to the Ca recovery device 2.

Similarly, the Mg recovery device 4 is provided with a concentrator 13 for concentrating the magnesium chloride aqueous solution, a condenser 14, and a storage tank 15 for storing the concentrated magnesium chloride aqueous solution. The Al recovery device 6 is provided with a concentrator 16 for concentrating the aluminum chloride aqueous solution, a condenser 17, and a storage tank 18 for storing the concentrated aluminum chloride aqueous solution. The Zn recovery device 8 is provided with a concentrator 19 for concentrating the zinc chloride aqueous solution, a condenser 20, and a storage tank 21 for storing the concentrated zinc chloride aqueous solution. A part or all of the condensed water (distilled water) of the three condensers 14, 17, and 20 is returned to the Mg recovery device 4, the Al recovery device 6, and the Zn recovery device 8, respectively.

As shown in FIG. 2, the K / Na removing device 1 includes a sludge filtering device 23 that filters the sludge introduced into the metal recovery device S. The sludge filtration device 23 is a continuous vacuum rotating cylindrical filter (for example, Oliver filter) provided with a cylindrical suction drum 25 arranged in the slurry tank 24. The sludge contains water, potassium, calcium, sodium, magnesium, aluminum, zinc, and inorganic solid components other than poorly water-soluble metal compounds (for example, fine-grained soil). , And an organic solid component, the water content thereof is, for example, 90 to 95%. Then, the sludge filtration device 23 separates the sludge into solid and liquid by filtration to generate a filtrate and a cake.

The cake that has been vacuum-sucked and adheres to the outer peripheral surface of the suction drum 25 (filter cloth) is washed with the washing water jetted from the sprinkler 26 on the outer peripheral surface of the suction drum 25 exposed to the air. As a result, potassium and sodium dissolved in the water in the cake are removed from the cake. Other water-soluble substances dissolved in the water in the cake are also washed with washing water and removed from the cake.

Thus, in the K / Na removal device 1 (sludge filtration device 23), a cake containing a poorly water-soluble calcium compound, magnesium compound, aluminum compound and zinc compound (for example, a water content of 70 to 85%), potassium content and sodium are added. A filtrate containing minutes is produced. Here, the cake is introduced into the Ca recovery device 2 (see FIG. 1), and the filtrate is introduced into a disposal site (not shown) and appropriately disposed of or processed. If the water content of the sludge introduced into the metal recovery device S is low (for example, 80 to 90%) and it is difficult to smoothly flow the sludge in the slurry tank 24, a mixing tank (not shown) is used in advance. ) Is charged with sludge and an appropriate amount of water, and the mixture is stirred with a stirrer (not shown) to generate a slurry having a water content of 90 to 95%, and this slurry may be supplied to the sludge filtration device 23.

As shown in FIG. 3, the Ca recovery device 2 mixes the cake generated by the sludge filtration device 23 (see FIGS. 1 and 2) of the K / Na removal device 1 with water and slurries (for example, water content). It is provided with a mixing tank 31 that produces 90% or more). A part or all of the condensed water of the condenser 11 (see FIG. 1) is used as water to be mixed with the cake in the mixing tank 31.

The mixing tank 31 is provided with a stirrer 32 and a motor 33 for rotationally driving the stirrer 32. The slurry produced in the mixing tank 31 is transported to the hydrochloric acid addition tank 35 by the slurry pump 34. The hydrochloric acid addition tank 35 is provided with a stirrer 36 and a motor 37 that rotationally drives the stirrer 36. In the hydrochloric acid addition tank 35, hydrochloric acid is added to the slurry produced in the mixing tank 31. The slurry in the hydrochloric acid addition tank 35 is introduced into the reaction tank 38. The reaction tank 38 is provided with a stirrer 39 and a motor 40 for rotationally driving the stirrer 39.

Specifically, in the hydrochloric acid addition tank 35, the amount of the slurry containing the poorly water-soluble calcium compound, magnesium compound, aluminum compound and zinc compound is smaller than the equivalent amount with respect to the calcium compound in the slurry (for example, 85 to 95% of the equivalent amount). Calcium is added. Most of the calcium compounds (for example, 95 to 99 wt%) are calcium carbonate (CaCO ₃ ). The majority of magnesium compounds (eg, 95-99 wt%) are magnesium oxide (MgO) and magnesium carbonate (MgCO ₃ ). The majority of aluminum compounds (eg, 95-99 wt%) are aluminum oxide (Al ₂ O ₃ ). The majority of zinc compounds (eg, 95-99 wt%) are zinc oxide (ZnO).

In general, when a relatively small amount of hydrochloric acid is added to a slurry containing a plurality of types of poorly water-soluble easily ionized metal compounds, the hydrochloric acid has the highest ionization tendency in the slurry (hereinafter, "maximum easily ionized metal"). It reacts preferentially or selectively with the compound of) to produce the maximum easily ionized metal chloride. Therefore, when the equivalent amount of hydrochloric acid with respect to the maximum easily ionized metal compound is added to such a slurry, most of the hydrochloric acid reacts with the maximum easily ionized metal compound to produce the maximum easily ionized metal chloride, while a small amount thereof. Hydrochloric acid reacts with a compound of an easily ionized metal (hereinafter referred to as "next easy ionized metal") having the next highest ionization tendency after the maximum easily ionized metal to produce a small amount of the next easily ionized metal chloride. Therefore, when the equivalent amount of hydrochloric acid is added to the maximum easily ionized metal compound, a small amount of the next easily ionized metal chloride is present as an impurity in the filtrate obtained by filtering the slurry (maximum easily ionized metal chloride aqueous solution). become.

Therefore, in the Ca recovery device 2, the slurry containing the poorly water-soluble calcium compound, magnesium compound, aluminum compound and zinc compound is provided with a smaller amount (for example, 85 to 95% of the equivalent amount) of chloride than the calcium compound in the slurry. By adding it, it is possible to prevent the poorly water-soluble magnesium compound and the like from changing to water-soluble chloride, and to prevent impurities such as magnesium chloride from being mixed in the filtrate (calcium chloride aqueous solution) obtained by filtering the slurry. I try to prevent it. In this case, a poorly water-soluble calcium compound remains in the cake obtained by filtering the slurry, and this calcium compound is removed by the Ca removing device 3 as described later.

Thus, in the hydrochloric acid addition tank 35 to the reaction tank 38, most of the poorly water-soluble calcium compounds (for example, 85 to 95%) are converted (chemically changed) into water-soluble calcium chloride by hydrochloric acid, and calcium chloride is converted to water. Dissolves in. The remaining calcium compounds (other than calcium chloride) do not change and do not dissolve in water. On the other hand, since the amount of hydrochloric acid is relatively small, the poorly water-soluble magnesium compound, aluminum compound and zinc compound in the slurry do not change and do not dissolve in water. Therefore, in the hydrochloric acid addition tank 35 to the reaction tank 38, the water-soluble calcium chloride, the poorly water-soluble calcium compound, the poorly water-soluble magnesium compound, the poorly water-soluble aluminum compound, and the poorly water-soluble zinc compound are used. A slurry containing is produced. The amount of water supplied to the mixing tank 31 is such that the slurry in the mixing tank 31, the hydrochloric acid addition tank 35, or the reaction tank 38 has sufficient fluidity to be transported by a pump (for example,). , The water content of the slurry is preferably adjusted to 90-95%).

The slurry in the reaction tank 38 is pumped to the filter press 42 by the slurry pump 41. In the filter press 42, the slurry is filtered to produce a filtrate containing calcium chloride and containing almost no impurities, and a cake containing a calcium compound (other than calcium chloride), a magnesium compound, an aluminum compound and a zinc compound. The filtrate, that is, the calcium chloride aqueous solution, is introduced into the concentrator 10, and the cake is introduced into the Ca removing device 3.

The concentrator 10 includes an evaporative can 44 containing an aqueous calcium chloride solution, a heater 45 that evaporates water by heating the aqueous calcium chloride solution in the evaporative can 44 with high-pressure steam, and drain (condensed water) in the heater 45. A drain trap 46 is provided to discharge the calcium chloride. In the concentrator 10, the calcium chloride aqueous solution is concentrated to a predetermined concentration (for example, 30 to 50 wt%) by vaporizing the water, and the concentrated calcium chloride aqueous solution is introduced into the storage tank 12 and temporarily stored. The water vapor generated in the evaporation can 44 is condensed by the condenser 11, and a part or all of the condensed water (distilled water) is returned to the Ca recovery device 2. The heater 45 may use a high-temperature heat medium such as Dowther (registered trademark) instead of high-pressure steam.

As shown in FIG. 4, the Ca removing device 3 mixes the cake generated by the filter press 42 (see FIG. 3) of the Ca recovery device 2, water, and hydrochloric acid to form a slurry (for example, a moisture content of 90%). The mixing tank 51 for producing the above) is provided. The mixing tank 51 is provided with a stirrer 52 and a motor 53 for rotationally driving the stirrer 52.

Specifically, in the mixing tank 51, the amount of the cake supplied from the Ca recovery device 2 is larger than the equivalent amount (for example, 105 to 110% of the equivalent amount) with respect to the poorly water-soluble calcium compound (residue) in the cake. Hydrochloric acid and an appropriate amount of water are added, and the mixture is stirred and mixed. As a result, the calcium compound (residual) is converted to calcium chloride by hydrochloric acid and dissolved in water. At this time, since hydrochloric acid is excessive with respect to the calcium compound, a part (small amount) of the poorly water-soluble magnesium compound contained in the cake becomes magnesium chloride and dissolves in water. Therefore, the magnesium recovery rate will be reduced accordingly. The amount of water supplied to the mixing tank 51 is such that the slurry in the mixing tank 51 has a fluidity that can be transported by a pump (for example, the water content of the slurry is 90 to 95). It is preferably adjusted (to be%).

Thus, in the mixing tank 51, a slurry containing calcium chloride, magnesium chloride, a magnesium compound (other than magnesium chloride), an aluminum compound, and a zinc compound is generated. The slurry in the mixing tank 51 is pumped to the filter press 55 by the slurry pump 54. In the filter press 55, the slurry is filtered to produce a filtrate containing calcium chloride and magnesium chloride and a cake containing a magnesium compound (other than magnesium chloride), an aluminum compound and a zinc compound. Since the filtrate is an aqueous solution in which a plurality of types of chlorides are mixed and has a low value as a resource, it is discharged to a disposal site for disposal or treatment. The cake is introduced into the Mg recovery device 4 (see FIG. 1).

As shown in FIG. 1 again, in the Mg recovery device 4, the magnesium chloride aqueous solution is produced by the same device and treatment method as in the case of the Ca recovery device 2, and the magnesium chloride compound, which is poorly water-soluble, is produced. Cakes containing aluminum and zinc compounds are produced. The magnesium chloride aqueous solution is concentrated in the concentrator 13 by the same apparatus and treatment method as the calcium chloride aqueous solution, and then stored in the storage tank 15. The cake is introduced into the Mg removing device 5. Since the configuration of the Mg recovery device 4 is basically the same as the configuration of the Ca recovery device 2 shown in FIG. 3, the illustration is omitted.

In the Mg removing device 5, basically the same device and treatment method as in the case of the Ca removing device 3 are used to prepare a filtrate containing magnesium chloride and aluminum chloride (small amount), a poorly water-soluble aluminum compound (other than aluminum chloride), and Cakes containing zinc compounds are produced. Since the filtrate is an aqueous solution in which a plurality of chlorides are mixed and has a low value as a resource, it is discharged to a disposal site and disposed of or treated. The cake is introduced into the Al recovery device 6. Since the configuration of the Mg removing device 5 is basically the same as the configuration of the Ca removing device 3 shown in FIG. 4, the illustration is omitted.

In the Al recovery device 6, an aqueous aluminum chloride solution is generated and a cake containing a poorly water-soluble aluminum compound and a zinc compound is generated by basically the same device and treatment method as in the case of the Ca recovery device 2. To. The aluminum chloride aqueous solution is concentrated in the concentrator 16 and then stored in the storage tank 18 by basically the same apparatus and treatment method as the calcium chloride aqueous solution. The cake is introduced into the Al removing device 7. Since the configuration of the Al recovery device 6 is basically the same as the configuration of the Ca recovery device 2 shown in FIG. 3, the illustration is omitted.

In the Al removing device 7, basically the same device and treatment method as in the case of the Ca removing device 3 are used to form a filtrate containing aluminum chloride and zinc chloride (small amount) and a cake containing a zinc compound (other than zinc chloride). Will be generated. Since the filtrate is an aqueous solution in which a plurality of chlorides are mixed and has a low value as a resource, it is discharged to a disposal site and disposed of or treated. The cake is introduced into the Zn recovery device 8. Since the configuration of the Al removing device 7 is basically the same as the configuration of the Ca removing device 3 shown in FIG. 4, the illustration is omitted.

In the Zn recovery device 8, the zinc chloride aqueous solution and the cake are produced basically by the same device and treatment method as in the case of the Ca recovery device 2. The zinc chloride aqueous solution is concentrated in the concentrator 19 by the same apparatus and treatment method as the calcium chloride aqueous solution, and then stored in the storage tank 21. The cake is discharged to the disposal site and disposed of or processed. Since the configuration of the Zn recovery device 8 is basically the same as the configuration of the Ca recovery device 2 shown in FIG. 3, the illustration is omitted.

As described above, according to the metal recovery method according to the present invention, zinc and a predetermined easy ionization from sludge containing zinc or a zinc compound and an easily ionized metal or a compound thereof can be carried out at a low cost by a relatively simple process or apparatus. The metal can be recovered in the form of a zinc chloride aqueous solution and an easily ionized metal chloride aqueous solution, each of which has high purity and contains almost no impurities.

S Metal recovery device, 1 Potassium / sodium removal device (K / Na removal device), 2 Calcium recovery device (Ca recovery device), 3 Calcium removal device (Ca removal device), 4 Magnesium recovery device (Mg recovery device) Equipment), 5 Magnesium removal device (Mg removal device), 6 Aluminum recovery device (Al recovery device), 7 Aluminum removal device (Al removal device), 8 Zinc content recovery device (Zn recovery device), 10 Concentrator , 11 Condenser, 12 Storage Tank, 13 Concentrator, 14 Condenser, 15 Storage Tank, 16 Concentrator, 17 Condenser, 18 Storage Tank, 19 Concentrator, 20 Condenser, 21 Storage Tank, 23 Sewage Filter, 24 Slurry Tank, 25 suction drum, 26 sprinkler, 31 mixing tank, 32 stirrer, 33 motor, 34 slurry pump, 35 hydrochloric acid addition tank, 36 stirrer, 37 motor, 38 reaction tank, 39 stirrer, 40 motor, 41 slurry pump, 42 filter press , 44 Evaporator, 45 Heater, 46 Drain Trap, 51 Mixing Tank, 52 Stirrer, 53 Motor, 54 Slurry Pump, 55 Filter Press.

Claims (1)

Metal plating, zinc chrome plating, molten zinc plating, or phosphoric acid production, which occurs at business establishments, other than water-soluble potassium compounds, water-soluble sodium compounds, calcium carbonate, zinc oxide, and the above four metal compounds. Calcium and zinc were recovered in the form of a concentrated calcium chloride aqueous solution and a concentrated zinc chloride aqueous solution, respectively, from a slurry-like sludge containing an inorganic solid component and an organic solid component having a water content of 90 to 95% . It is a metal recovery method
The metal recovery method includes a potassium / sodium removal step for removing a water-soluble potassium compound and a water-soluble sodium compound, a calcium recovery step for recovering calcium , a residual calcium removal step for removing residual calcium carbonate , and zinc. Has a zinc recovery step to recover ,
In the potassium / sodium removal step, the sludge is filtered through a continuous vacuum rotary cylindrical filter to produce a cake containing calcium carbonate, zinc oxide, the inorganic solid component and the organic solid component, while being water-soluble. Remove the filtrate containing the potassium compound and the water-soluble sodium compound,
The calcium recovery step
On slurried and stirred to mix water to the cake generated in the potassium sodium removal step, was added 85% to 95% hydrochloric acid equivalents to calcium carbonate in said cake, part of the calcium carbonate Is changed to calcium chloride and dissolved in water to produce a first slurry having a water content of 90 to 95% containing calcium chloride, calcium carbonate , zinc oxide , the inorganic solid component and the organic solid component . 1 Calcium addition step and
The first filtration step of filtering the first slurry with a filter press to produce a first filtrate containing calcium chloride and a first cake containing calcium carbonate, zinc oxide, the inorganic solid component and the organic solid component. When,
It has a calcium recovery step of heating the first filtrate to concentrate it by vaporizing water to produce a concentrated calcium chloride aqueous solution.
The residual calcium removal step
On slurried by stirring a mixture of water first cake, it was added from 105 to 110% of hydrochloric acid equivalents to calcium carbonate in the first cake in, dissolved in water of calcium carbonate by changing the calcium chloride A second hydrochloric acid addition step of producing a second slurry having a water content of 90 to 95% containing calcium chloride , zinc oxide , the inorganic solid component and the organic solid component, and the like.
The second slurry was filtered through a filter press, and a second filtrate containing calcium chloride, and a second filtration step to produce a second cake containing the oxide zinc and the inorganic solids and the organic solid components Have and
The zinc recovery step
On slurried by stirring a mixture of water in the second cake, adding 100-120% salt acid equivalents relative to zinc oxide in the second cake in, dissolved in water by changing the zinc oxide zinc chloride A third hydrochloric acid addition step of producing a third slurry having a water content of 90 to 95% containing zinc chloride , the inorganic solid component, and the organic solid component .
A third filtration step of filtering the third slurry to produce a third filtrate containing zinc chloride and a third cake.
A metal recovery method comprising a zinc recovery step of heating a third filtrate to concentrate it by vaporizing water to produce a concentrated zinc chloride aqueous solution .

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