TWI417249B - Method for manufacturing particle of ferric ferrous oxide powder - Google Patents

Description

Method for preparing particles of ferroferric oxide powder

The present invention relates to a process for preparing particles of ferroferric oxide powder, and more particularly to a process for preparing particles of ferroferric oxide powder using a waste liquid containing iron ions.

In the manufacturing process, steel mills produce a wide variety of wastes, where specific waste can be processed to make other products, thereby avoiding wasting any resources.

In the process of recycling waste acid, a general steel plant produces high-purity iron oxide powder through various production processes. However, the iron oxide powder produced in a conventional manner contains about 0.22 weight percent (wt%) of manganese (Mn), and for specific products such as chip inductors and garnets, the above The manganese content is still too high to meet its needs.

Among the conventional techniques, two of the methods for solving the above problem of excessive manganese content are as follows. In the first method, an appropriate amount of an alkaline neutralizing agent is added to an aqueous solution containing an iron salt having a high impurity concentration, followed by an oxygen-containing gas to carry out oxidation. The reaction solution is then filtered, thereby removing a portion of the iron and ferrite formed by the impurities. Subsequent addition of the desired alkaline neutralizing agent followed by the introduction of an oxygen-containing gas oxidizes the ferrous ion to form high purity triiron tetroxide. The disadvantage of the above method is that since the iron-containing waste acid solution of the general steel plant still contains a high concentration and a free acid which has not been reacted, this method not only fails to make good use of the free acid, but also consumes an additional alkaline neutralizer. , resulting in waste of resources and increased costs.

In the second method, the steel pickling waste liquid is first purified and purified, and then calcined to form iron oxide powder (Fe ₂ O ₃ ). Next, iron oxide powder or iron oxalate [Fe ₂ (C ₂ O ₄ ) ₃ ] is dissolved with hydrochloric acid, whereby iron chloride (FeCl ₃ ) is obtained. An alkaline solution is then added to bring the pH to 2.5 to 6.0. It is then heated to a temperature of 65 ° C to 99 ° C and maintained for more than 12 hours with a final pH of <1.5. Finally, the product was filtered, washed and dried to form a high-purity iron oxide powder having a manganese monoxide (MnO) concentration of 0.06 wt% and a cerium oxide (SiO ₂ ) concentration of 0.006 wt%. The second method has the disadvantage that the acid washing liquid is first calcined to form iron oxide powder, and then dissolved in hydrochloric acid, so that more energy is consumed.

Accordingly, the object of the present invention is to provide a method for preparing particles of ferroferric oxide powder, which can fully utilize the unreacted free acid remaining in the spent acid without burning, so that no additional alkaline neutralizing agent is consumed. And can reduce energy consumption.

According to an embodiment of the present invention, there is provided a method of preparing particles of ferroferric oxide powder. The method comprises dissolving a metal containing iron element at a first reaction temperature with a waste liquid containing iron ions to obtain a first reaction solution, wherein the first reaction temperature is 40 ° C to 99 ° C; and the first ammonia or alkali metal is used The hydroxide solution is added to the first reaction solution such that the pH of the first reaction solution is 2.5 to 6.0; the first reaction solution is filtered to obtain a second reaction solution; and the second ammonia or alkali metal hydroxide is The solution is added to the second reaction solution so that the pH of the second reaction solution is 3.0 to 9.0; at the second reaction temperature of 50 ° C to 95 ° C, an oxygen-containing gas is introduced to a pH of 3.0 to 9.0. Oxidation is carried out in the second reaction solution, and a third ammonia or alkali metal hydroxide solution is added to the second reaction solution so that the pH of the second reaction solution is 3.5 to 7.0 until there is no second in the second reaction solution. The ferrous iron ion (Fe ²⁺ ) is present; and the second reaction solution is filtered, washed, and dried to prepare particles of the ferroferric oxide powder.

According to still another embodiment of the present invention, in the above method for preparing particles of ferroferric oxide powder, the iron ion-containing waste liquid is selected from the group consisting of steel pickling waste liquid and utilizing capable of dissociating ferrous ions or A group of solutions prepared from ferric compounds of ferric ions.

According to still another embodiment of the present invention, in the above method for preparing particles of ferroferric oxide powder, before the step of adding the first ammonia or alkali metal hydroxide solution to the first reaction solution, The pH of a reaction solution is from 0 to 4.5.

The invention has the advantages that the cost of preparing the ferroferric oxide powder can be saved and the competitive advantage of the product price can be improved by making full use of the unreacted free acid in the spent acid and omitting the roasting process.

Please refer to FIG. 1 , which is a flow chart showing a method for preparing particles of ferroferric oxide (Fe ₃ O ₄ ) powder according to an embodiment of the present invention. The method 100 for preparing particles of ferroferric oxide powder (hereinafter referred to as "method 100" for convenience) starts at step 102 by dissolving a metal containing iron element at a first reaction temperature with a waste liquid containing iron ions. The first reaction solution is obtained, wherein the first reaction temperature described above is from 40 ° C to 99 ° C.

The method 100 proceeds to step 104, adding the first ammonia or alkali metal hydroxide solution to the first reaction solution obtained after the step 102 is performed, and adjusting the pH of the first reaction solution to make the first reaction solution. The pH is between 2.5 and 6.0.

The method 100 proceeds to step 106 to filter the first reaction solution treated in the above step 104 to obtain a second reaction solution. Next, in step 108, a predetermined amount of the second reaction solution is measured, pure water is added to adjust to a predetermined divalent iron ion concentration ([Fe ²⁺ ]), and the second ammonia or alkali metal hydroxide solution is added. In the above second reaction solution, the pH of the second reaction solution is adjusted so that the pH of the second reaction solution is 3.0 to 9.0.

After step 108 is completed, the method 100 proceeds to step 110, where an oxygen-containing gas is introduced into the second reaction solution having a pH of 3.0 to 9.0 at the second reaction temperature, and the third ammonia or alkali metal-containing hydrogen is introduced. The oxide solution is added to the second reaction solution. The pH of the second reaction solution is adjusted so that the pH of the second reaction solution is 3.5 to 7.0 until no divalent iron ions are present in the second reaction solution. Wherein the above second reaction temperature is from 50 ° C to 95 ° C. In a particular embodiment, the third ammonia or alkali metal hydroxide solution is substantially the same as the second ammonia or alkali metal hydroxide solution described above.

Finally, the method 100 proceeds to step 112, and the second reaction solution after the above step 110 is filtered, and the second reaction solution is washed and dried, thereby preparing a plurality of particles of ferroferric oxide powder.

In a specific embodiment, the iron ion-containing waste liquid in the above step 102 may be a pickling waste liquid used by a steel mill to treat steel. The above-mentioned steel pickling waste liquid dissolves the metal containing iron element, so that the free acid which has not been reacted in the spent acid can be fully utilized, and it is not necessary to consume an additional alkaline neutralizing agent, thereby avoiding an increase in manufacturing cost. However, the iron ion-containing waste liquid is not limited to the above-mentioned steel pickling waste liquid. In other embodiments, the iron ion-containing waste liquid may be a solution prepared by using an iron-containing compound, wherein the iron-containing compound can Dissociation of divalent iron ions or ferric ions (Fe ³⁺ ).

Further, before the step of adding the first ammonia or alkali metal hydroxide solution to the first reaction solution (i.e., before step 104), the pH of the first reaction solution is from 0 to 4.5.

In a specific embodiment, the hydroxides in the first, second, and third ammonia or alkali metal hydroxide solutions used in the above steps 104 and 108 may be ammonia, sodium hydroxide, or hydroxide. Potassium or any combination of the above.

In a specific embodiment, the oxygen-containing gas used in the above step 110 may be air, oxygen, ozone or any combination thereof.

Please refer to FIG. 2, which is a flow chart showing the sub-step of the step (step 110) of the method 100 of the method 100 of the first method in which the oxygen-containing gas is introduced into the second reaction solution having a pH of 3.0 to 9.0. Figure. In this embodiment, step 110 further includes step 202 and step 204. In step 202, the pH of the second reaction solution is detected. In step 204, when the pH of the second reaction solution is less than or equal to 6.0, the first, second or third ammonia-containing or alkali metal hydroxide solution is sequentially added to the second reaction solution in small amounts. The reaction rate in the second reaction solution is raised.

By adopting the method of the invention, in addition to the above, the free acid which has not been reacted in the waste acid can be fully utilized, and the baking process is not required, so that the energy consumption can be reduced, thereby saving the cost required for preparing the ferroferric oxide powder. . Furthermore, in the ferroferric oxide powder prepared by the method of the present invention, the manganese content can be much lower than the manganese content (about 0.22 wt%) in the iron oxide powder produced by the general waste acid recovery method, and the others. The contents of cerium (Si), calcium (Ca) and chlorine (Cl) are also significantly reduced, so that the purity of the iron oxide powder can be remarkably improved.

Hereinafter, the present invention will be specifically described by way of actual examples and comparative examples, but the scope of the present invention is not limited by the examples.

Example 1

First, weigh 1 kg of scrap and wash it with n-hexane. The cleaned scrap steel sheet was then placed in a 4 liter capacity retort and injected into 3 liters of cold rolling mill waste acid (i.e., the iron ion containing waste liquid in step 102 above). The above-mentioned distillation flask was placed in a water bath, and a steel strip reaction was carried out at a first reaction temperature of 90 ° C to obtain a ferrous chloride solution (that is, the first reaction solution in the above step 102).

Then, concentrated ammonia water (i.e., the first ammonia or alkali metal hydroxide solution in the above step 104) is added to the ferrous chloride solution to raise the pH to 4.0. Subsequently, the ferrous chloride solution is filtered to obtain a filtrate (i.e., the second reaction solution in the above step 106). Hydrochloric acid was then added to lower the pH of the filtrate to 1.0, and pure water was further added to adjust the volume molar concentration of the divalent iron ions of the filtrate so that the above-mentioned volume molar concentration was 2.9 M.

Next, 1241 ml (ml) of pure water was weighed and placed in a reactor of 2 liter capacity, and the number of blades for stirring in the reactor was set to 300 RPM (Revolutions Per Minute). 39 grams (g) of sodium hydroxide (NaOH) is placed in the reactor until the sodium hydroxide is completely dissolved in pure water (ie, the second ammonia or alkali metal hydroxide solution in step 108 above) .

After the above sodium hydroxide was completely dissolved in pure water, 259 ml was taken from the ferrous chloride solution (first reaction solution) having a volume molar concentration of 2.9 M of the above-mentioned divalent iron ions, and was successively added to the reactor. When the reaction has not yet started, this solution was mixed with the solution of ferrous chloride of the sodium hydroxide solution, it contains the number of moles of sodium hydroxide and twice the number of moles of divalent iron ion ratio R _N 0.65 . After the reaction, the pH of the mixed solution was 7.02 (that is, the pH of the second reaction solution was adjusted to 7.02).

After the above ferrous chloride solution was completely charged into the reactor, the temperature in the reactor (second reaction temperature) was raised to 75 °C. After the temperature reached 75 ° C, the rotation speed of the blades in the reactor was changed to 500 RPM, and 200 ml/min (ml/min.) of air was introduced.

When the pH of the second reaction solution drops to about 4.0, the amount of air introduced is reduced to 100 ml/min., and a small amount of sodium hydroxide solution is added successively (that is, the third ammonia in the above step 110 or The alkali metal hydroxide solution) maintains the pH of the second reaction solution between 3.8 and 4.6. The equivalent molar concentration of the hydroxide ion (OH ^- ) contained in the sodium hydroxide solution is 4 N. When the pH of the second reaction solution does not change downward, the reaction end point is reached, that is, no divalent iron ions are present in the second reaction solution.

After reaching the end of the reaction, the reaction solution was filtered, the filter cake was taken out, and the solid was dispersed in pure water. The above filtration and washing steps are carried out in the same place, thereby removing water-soluble impurities such as chloride ions (Cl ^- ) and sodium (Na ⁺ ) until the conductivity of the filtrate is less than 10 μm ohm/cm (μS/cm). Then, the filter cake was washed with alcohol, and then the filter cake was placed at 80 ° C until it was dried to obtain particles of high-purity ferroferric oxide powder.

In the following Examples 2 to 4, and Comparative Example 1, the implementation steps are similar to those of the embodiment 1, and therefore only the differences between the two will be described below.

Example 2

In Example 2, 1241 ml of pure water for dissolving sodium hydroxide was changed to 983 ml of pure water, and 39 g of sodium hydroxide was changed to 78 g of sodium hydroxide. The second reaction temperature was changed from 75 ° C to 80 ° C. Further, 259 ml of the ferrous chloride solution was changed to 517 ml of a ferrous chloride solution. In addition, when a small amount of sodium hydroxide solution is added successively, the pH is maintained between 4.0 and 5.0.

Example 3

In Example 3, 1241 ml of pure water for dissolving sodium hydroxide was changed to 723 ml of pure water, and 39 g of sodium hydroxide was changed to 135 g of sodium hydroxide. The second reaction temperature was changed from 75 ° C to 85 ° C. In addition, 259 ml of ferrous chloride solution was changed to 777 ml of ferrous chloride solution. In addition, when a small amount of sodium hydroxide solution is added successively, the pH is maintained between 4.5 and 5.2.

Example 4

In Example 4, 1241 ml of pure water for dissolving sodium hydroxide was changed to 983 ml of pure water, and 39 g of sodium hydroxide was changed to 90 g of sodium hydroxide. The second reaction temperature did not change and remained at 75 °C. Further, 259 ml of the ferrous chloride solution was changed to 517 ml of a ferrous chloride solution. In addition, when the end of the reaction was reached, the pH was raised to 6.0.

Comparative example 1

In Comparative Example 1, 1241 ml of pure water for dissolving sodium hydroxide was changed to 983 ml of pure water, and 39 g of sodium hydroxide was changed to 78 g of sodium hydroxide. Further, 259 ml of the ferrous chloride solution was changed to 517 ml of a ferrous chloride solution. In addition, when the reaction end point was reached, the pH was increased to 8.8.

Comparative example 2

When a high-purity iron oxide is produced by a general steel plant, it is firstly purified by dissolving the waste acid and then adding ammonia to obtain the first reaction liquid referred to in the present case, and then converting the ferrous chloride into iron oxide and hydrochloric acid by spray roasting. The manganese oxide and chlorine concentration of the iron oxide powder produced by the method are as high as about 0.22 wt% and about 0.10 wt%, respectively, and tend to be high.

The reaction conditions of the above Examples 1 to 4, Comparative Example 1 and Comparative Example 2 and the concentration of the main impurities contained therein are shown in Table 1 below.

Note: (1) pH (a) indicates the pH value of the mixed solution after the reaction of adding sodium hydroxide solution to the ferrous chloride solution (first reaction solution); (2) pH (b) indicates the second reaction After the pH in the solution drops to between 3 and 5, the sodium hydroxide solution is added to continue the reaction of the second reaction solution until the pH of the second reaction solution between the end points of the reaction is reached.

According to the data listed in Table 1 above, the particles of the ferroferric oxide powder obtained by the method of the present invention have a manganese content which is much smaller than that in the iron oxide powder produced by the general waste acid recovery method (comparative example). Manganese content (about 0.22% by weight). In addition, compared with the iron oxide powder produced by the general waste acid recovery method, the content of barium, calcium and chlorine is also significantly reduced, so the purity of the ferroferric oxide powder obtained by the method of the invention can be obtained. Significant improvement.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the present invention, and the present invention can be modified and modified without departing from the spirit and scope of the present invention. The scope is subject to the definition of the scope of the patent application attached.

100. . . Method for preparing particles of ferroferric oxide powder

102. . . step

104. . . step

106. . . step

108. . . step

110. . . step

112. . . step

202. . . step

204. . . step

For a better understanding of the present invention, reference is made to the above detailed description and the accompanying drawings. It is emphasized that, in accordance with the standard of the industry, the various features in the drawings are not to scale. In fact, the dimensions of the various features may be arbitrarily enlarged or reduced in order to clearly illustrate the above embodiments. The relevant schema description is as follows.

1 is a flow chart showing a method of preparing particles of ferroferric oxide powder according to an embodiment of the present invention.

Figure 2 is a flow chart showing the substeps of the step 100 of the method 100 of Figure 1 for introducing an oxygen-containing gas to a second reaction solution having a pH of 3.0 to 9.0 at a second reaction temperature.

100. . . Preparation of granules of ferroferric oxide powder

102. . . Step method

104. . . step

106. . . step

108. . . step

110. . . step

112. . . step

Claims (7)

A method for preparing particles of ferroferric oxide powder, comprising: dissolving a metal containing iron element at a first reaction temperature by using a waste liquid containing iron ions to obtain a first reaction solution, wherein the first reaction temperature a temperature of 40 ° C to 99 ° C; a first ammonia or alkali metal hydroxide solution is added to the first reaction solution, such that the first reaction solution has a pH of 2.5 to 6.0; the first reaction solution is filtered, Obtaining a second reaction solution; adding a second ammonia or alkali metal hydroxide solution to the second reaction solution, so that the second reaction solution has a pH of 3.0 to 9.0; at a second reaction temperature Passing an oxygen-containing gas to the second reaction solution having a pH of 3.0 to 9.0, and adding a third ammonia or alkali metal hydroxide solution to the second reaction solution, so that the second reaction The pH of the solution is 3.5 to 7.0 until no ferrous ions are present in the second reaction solution, wherein the second reaction temperature is 50 ° C to 95 ° C; and the second reaction solution is filtered, washed and dried to prepare a plurality of particles of ferroferric oxide powder . The method for preparing particles of ferroferric oxide powder according to claim 1, wherein the iron ion-containing waste liquid is selected from the group consisting of steel pickling waste liquid and utilizing capable of dissociating divalent iron ions or ferric iron ions. A group of solutions prepared from iron-containing compounds. The method for preparing particles of ferroferric oxide powder according to claim 1, before the step of adding the first ammonia, alkali metal or alkaline earth metal hydroxide solution to the first reaction solution, the first The pH of the reaction solution is from 0 to 4.5. The method for preparing particles of ferroferric oxide powder according to claim 1, wherein the first ammonia or alkali metal hydroxide solution, the second ammonia or alkali metal hydroxide solution, and the first The hydroxide in the three ammonia or alkali metal hydroxide solution is selected from the group consisting of ammonia water, sodium hydroxide, potassium hydroxide, and any combination thereof. A method of preparing particles of ferroferric oxide powder as described in claim 1, wherein the oxygen-containing system is selected from the group consisting of air, oxygen, ozone, and any combination thereof. The method for preparing particles of ferroferric oxide powder according to claim 1, wherein the step of introducing the oxygen-containing gas to the second reaction solution having a pH of 3.0 to 9.0 at the second reaction temperature further comprises : detecting a pH value of one of the second reaction solutions; and when the pH of the second reaction solution is less than or equal to 6.0, the first ammonia or alkali metal hydroxide solution, the second ammonia or An alkali metal hydroxide solution or the third ammonia or alkali metal hydroxide solution is added to the second reaction solution to thereby increase the reaction rate in the second reaction solution. The method for preparing particles of ferroferric oxide powder according to claim 1, wherein the second ammonia or alkali metal hydroxide solution is substantially the same as the third ammonia or alkali metal hydroxide solution.