KR20130009697A - Separation method of silicon dioxide and magnesia using ferronickel slag, menufacturing method of a fertilizer containing silicic acid and magnesia - Google Patents

Abstract

PURPOSE: A separation method of silicon dioxide and magnesia from a ferronickel slag and a manufacturing method of silicic acid and a magnesium fertilizer using the separation method are provided to reduce processing costs of the ferronickel slag by manufacturing a fertilizer using the ferronickel slag that is produced while processing ferronickel and to manufacture a high-quality fertilizer by using a slag with abundant minerals. CONSTITUTION: A separation method of silicon dioxide and magnesia from a ferronickel slag comprises steps of: obtaining a ferronickel slag powder by processing a massive ferronickel slag, separating a first filtration solution including magnesium and an insoluble precipitate including silicon dioxide by adding an acid to the ferronickel slag powder, and collecting the magnesium as magnesia by processing the first filtration solution. A pre-processing phase comprises steps of: pulverizing the massive ferronickel slag, sintering after adding lime to the pulverized ferronickel slag, obtaining the ferronickel slag powder by grinding the sintered ferronickel slag, and separating iron and nickel contained in the ferronickel slag powder using magnetic force. [Reference numerals] (A1) Ferronickel slag; (A2) Pulverizing; (A3) Plasticizing; (A4) Grinding; (A5) Magnetic separation of Fe and Ni; (A6) Acid reaction; (A7) First filtration; (BB) Lime; (C1) First filtration solution; (C2) PH adjustment; (C3) Second filtration; (DD) Metal impurities; (E1) Second filtration solution; (E2) Mg(OH)_2 precipitation; (E3) Third filtration; (FF) Third filtration solution; (G1) Mg(OH)_2 precipitate; (G2,J5) Drying; (G3) Calcination; (H1) Insoluble precipitate; (H2) SiO_2 extraction; (H3) Fourth filtration; (II) Residual precipitate; (J1) Fourth filtration solution; (J2) SiO_2 precipitation; (J3) First pickling; (J4) Second pickling; (KK) CO_2 gas

Description

Separation method of silicon dioxide and magnesia using ferronickel slag, Menufacturing method of a fertilizer containing silicic acid and magnesia}

The present invention relates to a method for separating silicon dioxide and magnesia from ferronickel slag and a method for producing silicic acid and high-fertilizer using the same, and more specifically, ferronickel slag generated during the melt reduction process of ferronickel as a starting material The present invention relates to a method for separating silicon dioxide and magnesia, which are the components of high purity, and a method for producing silicic acid and fertilizer using the same.

Ferronickel, a raw material of stainless steel, is an alloy having a composition of 20wt% Ni ~ 80wt% Fe, and is generally manufactured by reducing ore in an electric furnace by reducing ore. Nickel ores for producing ferronickel are supplied domestically in New Caledonia. The mineral phase of New Caledonia mines is mostly Sariteite of Laterite. And New Caledonia's ore is considered to be the best ore due to its high nickel purity and low impurity content. All the oxide ores of SMSP of New Caledonia are supplied to Korea.

The main components of nickel ore are 38% SiO ₂ and 25% MgO, while active metals contain 2.3% Ni and 11% Fe.

The main processes of ferronickel are produced through pretreatment of raw materials, drying, preliminary reduction, melting reduction (electric furnace process), refining, and casting. Among them, slag, which is a by-product of the electric furnace process, is produced. It is called a ferronickel slag.

The main components of general ferronickel slag are shown in Table 1 below.

ingredient CaO SiO ₂ Al ₂ O ₃ MgO T.Fe T.Ni basicity Content (wt%) 0.01 54.0 2.0 35.0 2.0 ~ 5.0 0.002 0.65

As shown in Table 1, the ferronickel slag is SiO ₂ About 54%, MgO 34%, and most of the other metals such as Fe occupy, which is similar to the serpentine and its chemical composition is high value as a fertilizer.

Korean Unexamined Patent Publication No. 20110136596 discloses a fertilizer manufacturing method using ferronickel slag. The prior art disclosed is a grinding step of grinding the ferronickel slag into powder, a mixing step of mixing the prepared phosphorite powder with the ferronickel slag powder to form a mixture, a melting step of heating and melting the mixture, and a melting step A cooling step of cooling the melt formed, and a post-treatment step of drying and grinding the solids cooled in the cooling step to produce a fertilizer containing soluble silicic acid and alkali powder, soluble phosphate, soluble soluble soil and the like. will be.

The conventional technique is not a method of extracting fertilizer components such as silicic acid or goto from ferronickel slag, but because ferronickel slag is processed and used as a fertilizer, it is impossible to adjust the fertilizer components, and the content of the main fertilizer components. There is a problem that this is low.

The present invention is to separate the silicon dioxide and magnesia to extract the fertilizer components of silicon dioxide and magnesia from ferronickel slag with high value as a fertilizer to be used as raw materials of fertilizer and silicic acid and high-fertilizer using the same The purpose is to provide a method of manufacturing.

Separation method of silicon dioxide and magnesia from the ferronickel slag of the present invention for achieving the above object is a pre-treatment step of processing the bulk ferronickel slag to obtain a ferronickel slag powder; Leaching step of adding an acid to the ferronickel slag powder to separate the first filtrate containing magnesium and the insoluble precipitate containing silicon dioxide; A magnesia recovery step of recovering the magnesium in the form of magnesia by treating the first filtrate; and the pretreatment step includes a) coarsely pulverizing the bulk ferronickel slag, and b) the coarsely pulverized ferro. Calcining after adding lime to the nickel slag, c) pulverizing the calcined ferronickel slag to obtain the ferronickel slag powder, and d) magnetically treating iron and nickel contained in the ferronickel slag powder. It characterized in that it comprises a step of separating.

In the leaching step, the ferronickel slag powder was mixed at a ratio of 300 to 400 g per 1 L of hydrochloric acid at a concentration of 50%, stirred at 70 to 100 ° C. for 6 to 8 hours, and then filtered to filter the first filtrate and the insoluble precipitate. It characterized in that to separate.

The magnesia recovery step is a) adding sodium hydroxide to the first filtrate to adjust the pH to 5 to 7 to precipitate metal impurities other than magnesium, b) filtering the first filtrate and the metal impurities and Separating into a second filtrate, c) adding sodium hydroxide to the second filtrate and adjusting the pH to 9 to 11 to precipitate magnesium hydroxide, and d) filtering the hydroxide to filter the second filtrate. And separating into a magnesium precipitate and a third filtrate, and e) drying the magnesium hydroxide precipitate at calcination at 800 to 1000 ° C. to oxidize to magnesia.

And a silicon dioxide recovery step of recovering the silicon dioxide by treating the insoluble precipitate separated in the leaching step.

The silicon dioxide recovery step is a) adding a sodium hydroxide solution to the insoluble precipitate leaching silicon dioxide contained in the insoluble precipitate, and b) filtering the remaining precipitate and sodium hydroxide solution of the silicon dioxide leached out and the fourth Separating into a filtrate, c) injecting carbon dioxide into the fourth filtrate to precipitate silicon dioxide, and d) separating the silicon dioxide precipitate by filtering the fourth filtrate, e) First pickling the silicon dioxide precipitate with a hydrochloric acid solution; and f) pickling and drying the silicon dioxide precipitate with a pickling solution in which a hydrogen fluoride solution and a hydrochloric acid solution are mixed after the first pickling. do.

In addition, the silicic acid and the high-fertilizer manufacturing method of the present invention is characterized in that the production method using the silicon dioxide and magnesia separated from the ferronickel slag by the separation method as a raw material.

As described above, according to the present invention, silicon dioxide and magnesia as fertilizer components can be extracted with high purity from ferronickel slag.

In addition, the present invention manufactures fertilizers using ferronickel slag generated during the processing of ferronickel, reducing the processing cost of ferronickel slag, using the mineral-rich slag to manufacture fertilizers can produce a good fertilizer There is an advantage.

1 is a block diagram schematically showing a separation method according to an embodiment of the present invention,
2 is MgSO ₄ with temperature And a graph showing the solubility of MgCl ₂ in water,
3 is a graph showing the leaching rate of magnesium according to the concentration of hydrochloric acid solution,
4 is a graph showing the leaching rate of magnesium according to the reaction temperature,
5 is a graph showing the content of magnesium according to the pH of the first filtrate,
6 and 7 are SEM pictures of the recovered magnesia,
8 is a SEM photograph of the recovered silicon dioxide.

Hereinafter, a method of separating silicon dioxide and magnesia from ferronickel slag according to a preferred embodiment of the present invention and a method of preparing silicic acid and high-fertilizer using the same will be described in detail.

Referring to FIG. 1, a method for separating silicon dioxide and magnesia from ferronickel slag according to an embodiment of the present invention includes a pretreatment step, a leaching step, a magnesium recovery step, and a silicon dioxide recovery step.

In the pretreatment step, the bulk ferronickel slag is processed to obtain ferronickel slag powder. The pretreatment step includes, for example, coarsely pulverizing a bulky ferronickel slag, adding lime to the coarsely pulverized ferronickel slag, and calcining, and pulverizing the calcined ferronickel slag to ferronickel slag powder. Obtaining a step of separating the iron and nickel contained in the ferronickel slag powder by magnetic force.

Ferronickel slag used as the starting material of the present invention is a by-product in the ferronickel plant. Ferronickel slag is a slag generated during the melt reduction process of an electric furnace in the manufacture of ferronickel. Such ferronickel slag has the advantage of high content of silicic acid (silicon dioxide) and goto (magnesia) as well as less impurities than blast furnace slag.

The bulk ferronickel slag is ground to a particle size of about 5 to 10 mm through coarse grinding, which is roughly ground using a crusher. Ferronickel slag itself is low in the content of the fertilizer component in the present invention is calcined after the addition of lime. Lime lime or quicklime can be used. Lime may be added from 20 to 100 parts by weight based on 100 parts by weight of ferronickel slag. The addition of lime can increase the content of fertilizer components. This seems to be due to the change of mineral phase due to the firing of Si-Mg bond of ferronickel slag. Firing takes place at about 1100 to 1300 ° C for about 1 to 3 hours. Through the firing process, the mixture of ferronickel slag and lime is sufficiently heated and melted. If the mixture is not heated sufficiently, the melting and recrystallization of the mineral phase will be insufficient, resulting in a decrease in the content of the fertilizer.

After firing, the mixture is cooled and then pulverized to obtain ferronickel slag powder. The pulverization process is pulverized into a powder form using a hammer mill, a ball mill, a roche mill, or the like. The powder level of the pulverized ferronickel slag is suitably 3000 to 5000 cm ² / g. After grinding, magnetic metals such as iron and nickel contained in the ferronickel slag powder are separated magnetically.

As described above, ferronickel slag powder from which magnetic metals such as iron and nickel are removed through the pretreatment step is separated into a first filtrate containing magnesium and an insoluble precipitate containing silicon dioxide. The leaching step is carried out by adding acid to the ferronickel slag powder. For example, the ferronickel slag powder per 1 L hydrochloric acid solution with a concentration of 50% in a ratio of 300 to 400g and stirred at 70 to 100 ℃ for 6 to 8 hours to react with the acid.

Through the reaction with hydrochloric acid solution and ferronickel slag, metals (Ca, Al, Mg, etc.) contained in the ferronickel slag are leached to exist in the form of hydrochloride. Silicon dioxide does not dissolve in hydrochloric acid but exists as an insoluble precipitate. The reaction scheme of ferronickel slag and hydrochloric acid is as follows.

Ferronickel slag + HCl → SiO ₂ ↓ + M (Cl) n, M = Ca, Al, Mg ...

When the reaction with hydrochloric acid is completed, the reaction is carried out and then filtered to separate the first filtrate and the insoluble precipitate. Filtration can be easily filtered using filter paper. In addition to that can be filtered using a variety of filters capable of separating solid-liquid.

By separating the first filtrate and the insoluble precipitate through the leaching step described above, the first filtrate may be treated to recover magnesium in the form of magnesia. In addition, silicon dioxide can be recovered by treating the insoluble precipitate separated from the first filtrate.

In the magnesia recovery step to recover magnesia, sodium hydroxide (NaOH) solution may be added to the first filtrate to remove impurities while minimizing the loss of magnesium through pH adjustment. Selective precipitation according to pH is applied to hydrolysis reaction to separate magnesium from major impurities such as Fe, Ni and Al. In general, Fe, Al is formed as a hydroxide precipitate in a relatively low pH region between pH 3.0 ~ 4.0, depending on the conditions, Ni is most likely to rise to pH 6.0, which is a neutral region to form most hydroxide precipitate.

Therefore, sodium hydroxide solution is added to the first filtrate to adjust the pH to 5 to 7 to precipitate metal impurities other than magnesium as hydroxides. Next, the first filtrate is filtered to separate the precipitated metal impurities and the second filtrate. The second filtrate is adjusted to pH 9-11 by adding sodium hydroxide solution to the second filtrate to precipitate magnesium present in the second filtrate. Most magnesium in the pH 9-11 range precipitates out of magnesium hydroxide (Mg (OH) ₂ ). This second filtrate is filtered to separate the magnesium hydroxide precipitate and the third filtrate. It is desirable to minimize the remaining Na ⁺ ions by washing with water several times during the filtration process. The separated magnesium hydroxide precipitate may be dried and then calcined at 800 to 1000 ° C. to be oxidized to magnesia (MgO).

The magnesia recovery step may recover about 99.8% high purity magnesia.

On the other hand, it is also possible to recover the silicon dioxide by treating the insoluble precipitate separated from the first filtrate. Insoluble precipitate, silicon dioxide, can be effectively recovered from the insoluble precipitate by leaching with sodium hydroxide.

First, a sodium hydroxide solution is added to an insoluble precipitate to leach silicon dioxide contained in the insoluble precipitate. Next, the sodium hydroxide solution in which silicon dioxide is leached is filtered and separated into the remaining precipitate and the fourth filtrate. In order to precipitate silicon dioxide contained in the fourth filtrate, carbon dioxide is injected into the fourth filtrate to precipitate silicon dioxide. The fourth filtrate containing precipitated silicon dioxide may be filtered to separate the silicon dioxide precipitate. The separated silicon dioxide precipitate contains Fe, Na, Ca, Mg, Al and the like. These impurities can be removed through primary and secondary pickling processes. For example, the silicon dioxide precipitate is first pickled with a hydrochloric acid solution and then the silicon dioxide precipitate is pickled secondly with a pickling solution in which a hydrogen fluoride solution and a hydrochloric acid solution are mixed. And impurities are removed through the pickling process and dried to recover high purity silicon dioxide with a purity of about 99.9%.

As described above, the present invention can separate high purity magnesia and silicon dioxide from ferronickel slag. Meanwhile, unlike the above description of the present invention, only one of the magnesia recovery step and the silicon dioxide recovery step may be selectively performed.

Separated high purity silicon dioxide and magnesia are useful sources of fertilizer. Only magnesia can be used as the main raw material of high-fertilizer, and only silicon dioxide can be used as the main raw material of silicate fertilizer. In addition, magnesia and silicon dioxide can be used simultaneously as the main raw material of silicic acid and goto fertilizer. The method for producing fertilizer using magnesia and silicon dioxide as a raw material applies a well-known technique, so a detailed description thereof will be omitted.

Hereinafter, the present invention will be described through production examples. However, the following experimental example is for describing the present invention in detail, and the scope of the present invention is not limited to the following experimental example.

<Production Example>

1. Pretreatment Experiment

Ferronickel slag produced by SNNC Co., Ltd. was used as a raw material used in this experiment. The composition was confirmed by chemical analysis of ferronickel slag. The analysis results are shown in Table 2 below.

ingredient SiO ₂ MgO Al ₂ O ₃ CaO Fe ₂ O ₃ NiO TiO ₂ MnO ₂ Content (wt%) 52.4 34.5 2.45 0.65 4.5 0.05 0.05 0.26

As shown in Table 2, the SiO ₂ content was 52.4% and the MgO content was found to be 34.5%. That is, the main components of the ferronickel slag used as the raw material was SiO ₂ , MgO, it could be confirmed that the Fe, Al ₂ O ₃ and the like.

In order to examine the effects of calcining and lime addition, the contents of fertilizer components before and after firing of ferronickel slag powder without lime and the contents of fertilizer components before and after firing of ferronickel slag powder added with lime were analyzed. The pulverized ferronickel slag powder showed a pass rate of 300mesh 90%, and the powder level was about 4,000 cm ² / g as a result of Blaine measurement (KS L 5106). The mill used for pulverizing ferronickel slag was a vibrating mill (WBTM-10, Woongbi Machinery) and Ball was used as the grinding media.

First, coarse pulverization of ferronickel slag first and then finely pulverized ferronickel slag powder (sample 1) and ferronickel slag first coarsely pulverized in an electric furnace for 2 hours and then fired secondly The pulverized waste nickel slag powder (sample 2) was measured by soluble silicic acid, soluble soil, and alkaline powder by fertilizer process test. The results are shown in Table 3 below.

division Soluble silicic acid (wt%)
Perchloric acid method Oil-soluble Goto (wt%)
(EDTA titration law) Alkaline powder (wt%)
(EDTA titration law) Sample 1 (before firing) 0.4 0.1 4.6 Sample 2 (after firing) 0.3 0.1 9.4

Referring to Table 3, the ferronickel slag before firing was found to be 0.4% of soluble silicic acid, 0.1% of soluble silt, and 4.6% of alkaline powder. After firing, the soluble silicic acid and the soluble soil were insignificant, but the alkali content increased to 9.4%, but it was confirmed that the active ingredient was insufficient to be used as a fertilizer.

Next, in order to examine the change in the composition of the ferronickel slag when lime is added, the ferronickel slag is first coarsely pulverized, and then 60 parts by weight of lime (calcined lime) is added to 100 parts by weight of ferronickel slag, and then the second After the pulverized ferronickel slag powder (sample 3) and ferronickel slag were first coarsely ground, 60 parts by weight of lime (calcined lime) was added to 100 parts by weight of ferronickel slag, and then calcined at 1200 ° C. in an electric furnace for 2 hours. Secondary finely ground pulverized nickel slag powder (Sample 4) was measured by soluble silicic acid, oil soluble soil, alkali powder by fertilizer process test method and the results are shown in Table 4 below.

division Soluble silicic acid (wt%)
Perchloric acid method Oil-soluble Goto (wt%)
(EDTA titration law) Alkaline powder (wt%)
(EDTA titration law) Sample 3 (before firing) 0.4 0.5 21.2 Sample 4 (after firing) 13.6 5.7 24.1

Comparing the results of Table 4 with the results of Table 3, the soluble soluble soil was slightly increased by the addition of lime, and the alkali powder was greatly increased. In addition, when calcined by adding lime, soluble silicic acid and soluble clay were significantly increased compared with before calcining. This is because the lime component breaks the Si-Mg bond of ferronickel slag and the mineral phase changes due to the calcination.

Through the above experimental results, it was confirmed that the addition of lime rather than the ferronickel slag alone can greatly increase the content of the fertilizer component.

2. Leaching Experiment

Sulfuric acid and hydrochloric acid were examined as acids for leaching magnesium from ferronickel slag powder. Magnesium present in the form of Mg ₂ SiO ₄ or MgSiO ₄ in ferronickel slag is leached into the magnesium salt by H ₂ SO ₄ or HCl. Leaching of magnesium can be represented by the following reaction.

Mg ₂ SiO ₄ or MgSiO ₄ + H ⁺ → Mg ^{2 +} + H ₄ SiO ₄ + H ₂ O

In order to examine the optimum acid, the solubility of magnesium salts (MgSO ₄ , MgCl ₂ ) in the reaction of ferronickel slag with sulfuric acid or hydrochloric acid was examined.

Referring to FIG. 2, the solubility of MgCl ₂ was found to be greater than MgSO ₄ . MgSO ₄ showed a maximum value at 80 ° C., but the solubility decreased with increasing temperature. On the other hand, the solubility of MgCl ₂ increased continuously with increasing temperature. Therefore, it was considered advantageous to use hydrochloric acid for the separation of fertilizer components from ferronickel slag.

Next, magnesium leaching experiments were performed using hydrochloric acid solutions of different concentrations to determine the appropriate concentration of hydrochloric acid. After preparing hydrochloric acid solution of 100%, 50% and 20% concentration, ferronickel slag was added little by little and adjusted to 350g / l ratio, and the leaching reaction was carried out at a stirring speed of 180rpm. Figured out. The results are shown in Fig.

Referring to FIG. 3, in the case of 20% hydrochloric acid solution, the Mg leaching rate of less than 50% is shown even over time, whereas the 50% hydrochloric acid solution and 100% hydrochloric acid solution showed almost similar leaching pattern, and the 100% hydrochloric acid solution is After 3 hours, 50% hydrochloric acid solution showed almost 100% Mg leaching rate. A concentration of 50% was determined to be appropriate as a hydrochloric acid solution.

Next, ferronickel slag was added little by little to 50% hydrochloric acid solution to adjust the leaching effect according to the temperature during the reaction with acid, and the leaching reaction was proceeded at a stirring speed of 180rpm. Maintained the leaching rate of Mg compared to the raw material over time while maintaining at 40 ℃, 70 ℃, 100 ℃. The results are shown in FIG.

Referring to FIG. 4, the higher the temperature, the shorter the time to reach the 100% leaching rate, and the 98% leaching rate was reached after 4 hours at 100 ° C. At 70 ° C., the leaching rate of 99% was reached after about 6 hours. On the other hand, the leaching rate did not rise to more than 60% even after 10 hours at 40 ℃. In particular, 40 ℃, 70 ℃, 100 ℃ did not show a significant difference depending on the temperature until 2 hours, which seems to be due to the exothermic reaction of the initial reaction.

Next, experiments were performed by varying the mixing ratio to see the magnesium leaching rate according to the mixing ratio of ferronickel slag and hydrochloric acid solution. Ferronickel slag was added little by little into 50% hydrochloric acid solution, and the mixture was adjusted to a constant mixing ratio, followed by reaction at 70 ° C. at a stirring speed of 180 rpm for 6 hours. The leaching rate of Mg relative to the raw materials according to the mixing ratio was identified and the results are shown in Table 5 below.

Mixing ratio 1000g / ℓ 500 g / ℓ 400 g / ℓ 350 g / ℓ 300 g / ℓ 100 g / ℓ Mg leaching rate 71.0% 96.3% 99.0% 99.3% 99.1% 98.7%

Referring to Table 5, the Mg leaching rate was found to be the best at the mixing ratio of 300g / L ~ 400g / L at the same conditions.

To summarize the above experimental results, the leaching of ferronickel slag powder 300 to 400 g per 1 liter of hydrochloric acid solution with a concentration of 50% and stirring at 180 rpm for 6 to 8 hours at 70 to 100 ℃ is optimized for magnesium leaching. Judging by

3. Magnesia recovery experiment

Based on the above experimental results, after performing the optimal pretreatment and leaching process, the magnesia recovery experiment was performed. That is, after coarse grinding of ferronickel slag firstly, 60 parts by weight of lime (calcined lime) is added to 100 parts by weight of ferronickel slag, and then calcined in an electric furnace at 1200 ° C. for 2 hours and then finely pulverized in second. Powder was prepared. Then, 350 g of ferronickel slag powder prepared in 1 L of hydrochloric acid solution having a concentration of 50% was added, and stirred at 180 rpm for 6 hours at 70 ° C. for reaction. After the reaction, the resultant was filtered with a filter paper to separate the first filtrate and the insoluble precipitate. The separated insoluble precipitate was used in the silicon dioxide recovery experiment to be described later.

Here, the optimum conditions for recovering high purity magnesia by treating the separated first filtrate were tested. As a first step for recovering magnesia, a method of precipitating magnesium salts contained in the first filtrate in the form of hydroxide using sodium hydroxide was selected.

Since the separated first filtrate contains a large amount of impurities such as Fe, Ni, Al, Ca, Cr, Mn together with Mg, coprecipitation may also occur when impurities are precipitated from magnesium. Therefore, the semen method by selective precipitation according to pH was examined as a process for separating Mg from major impurities such as Fe, Ni, and Al.

In general, Fe and Al are formed as a hydroxide precipitate in a relatively low pH region between pH 3.0 ~ 4.0, depending on the pH conditions, Ni forms most of the hydroxide precipitate in the vicinity of pH 6.0, which is almost neutral. Therefore, it is possible to separate the impurities and Mg by separating the Mg precipitation pattern in the first filtrate.

To this end, NaOH solution was added to the first filtrate, and the pH was gradually raised to analyze the Mg content of the first filtrate for each pH, thereby identifying a decrease from the initial stage.

Referring to FIG. 5, the concentration of Mg contained in the first filtrate until the pH 7.0 proceeds almost similar to the initial stage, and then rapidly decreases above pH 7.0. Therefore, it is expected to remove major impurities such as Fe, Al, and Ni while minimizing the loss of Mg only by adjusting the pH.

 In order to compare the components before and after pH adjustment, sodium hydroxide solution was added to the first filtrate to adjust the pH to 6.0, and the results of the comparative analysis of impurities and Mg content before and after pH adjustment were shown in Table 6 below.

ingredient Fe (mg / L) Ni (mg / L) Cr (mg / ℓ) Mn (mg / L) Al (mg / l) Mg (g / ℓ) Before pH adjustment 8590 100 730 300 910 4.67 After pH adjustment 3 0 0.2 32 1.7 4.52

Referring to Table 6, when the pH was adjusted to 6.0, there was almost no change in the Mg content in the first filtrate, but it was found that the content of impurities was greatly reduced. This is because impurities were precipitated in hydroxide form by pH adjustment.

After the precipitate was precipitated, the first filtrate was filtered to separate the precipitated metal impurities and the second filtrate. In order to precipitate the magnesium present in the separated second filtrate, sodium hydroxide solution was added to the second filtrate, and the second filtrate was adjusted to pH 9 to 11 to convert magnesium into magnesium hydroxide (Mg (OH) ₂ ). After precipitation, the second filtrate was filtered to separate the magnesium hydroxide precipitate and the third filtrate. The separated magnesium hydroxide precipitate was dried and calcined at 900 ° C. to finally recover magnesia (MgO).

The purity of the recovered magnesia was found to be 99.8%. Since the purity of commercially available goto is 99.8% or less, it was determined that magnesia recovered in the present invention could be used as a raw material for goto fertilizer.

Scanned electron microscope (SEM, JEOL JSM-T330A) photographs of the recovered magnesia are shown in FIGS. 6 and 7. After calcination, the agglomeration of particles was observed, and thus the particle size distribution was widely present. The aggregation of such particles can be sufficiently solved by a calcination process after calcination.

4. Silicon dioxide recovery experiment

An experiment was conducted to recover silicon dioxide using an insoluble precipitate separated from the first filtrate. In order to recover high-purity SiO ₂ from insoluble precipitate containing SiO ₂ as the main component, an efficient process to minimize the treatment cost was applied to recover SiO ₂ powder having a purity of 99.9% or more.

First, the components of the insoluble precipitate separated from the first filtrate are analyzed and shown in Table 7.

ingredient SiO ₂ MgO Al ₂ O ₃ CaO Fe Ni Cr Content (wt%) 42.7 0.3 0.1 0.01 1.5 0.02 0.01

Analysis of insoluble precipitates in Table 7 showed that MgO, CaO, Fe, Cr as well as Al ₂ O ₃ were removed from the raw materials. Therefore, the pickling treatment was expected to remove MgO and Fe with Al ₂ O ₃ additionally. This process is the simplest and most economical process that can be reviewed to recover high quality SiO ₂ .

In the experiment, the insoluble precipitate was adjusted to 100 g / L in inorganic acids (hydrochloric acid and nitric acid), and then reacted at 100 ° C. for 6 hours and filtered to analyze each residue. As a result, a large amount of impurities were found in the residue. It was found that the pickling process using hydrochloric acid or nitric acid had a limitation in removing impurities, and thus, it was found to be inadequate as a process for recovering high purity silicon dioxide.

Therefore, the pickling process was applied using HF, a powerful disintegrant. After the insoluble precipitate was reacted with HF, the recovered Si (OH) ₄ was calcined at high temperature to recover the final SiO ₂ . In the experiment, 50 g of the residue was added to HF solution diluted 1: 1 with water and reacted. After filtering, the resultant was neutralized and filtered to NH ₄ OH as a precipitant to adjust the pH to 2.0 to 3.0. The precipitated Si (OH) ₄ NH ₂ O precipitate was then calcined at 1000 ° C. The weight of SiO ₂ recovered after calcination was 26.6 g, which was more than 21.3 g of analytical value. The results of the quantitative analysis through ICP are shown in Table 8 below.

ingredient SiO ₂ Mg Al Ca Fe Ni Na Content (wt%) 80 0.7 0.1 4.2 0.03 0.01 7.4

Referring to Table 8, Na and Ca are severely polluted by several percent, and Mg and Al also show too high contents based on high purity of 99.99%, which is limited to recovering only Si by precipitation by hydrolysis. Was found to exist. Therefore, another recovery method was sought, and a NaOH leaching process was applied.

This process is based on the leaching property that SiO ₂ is selectively leached into NaOH solution, and precipitates SiO ₂ by blowing CO ₂ gas into the fourth filtrate obtained by leaching with NaOH solution and filtering. It is additionally removed to recover high quality SiO ₂ .

Specifically, 200 ml of 25% NaOH solution was added to 50 g of an insoluble precipitate, followed by leaching at 70-80 ° C. for 6 hours, followed by filtration to separate the fourth filtrate and the remaining precipitate. While stirring the fourth filtrate at a rate of 180 rpm at room temperature, CO ₂ gas was blown at a rate of 5 L / min for 30 minutes, and white SiO ₂ precipitation began to gradually occur after about 10 minutes. SiO ₂ Filtration after precipitation to precipitate SiO ₂ Sediment is separated, and separated SiO ₂ The precipitate was first pickled with stirring at 80 ° C. with 50% HCl solution and dried at 100 ° C. The SiO ₂ recovered immediately after drying was analyzed and shown in Table 9 below.

division Cu Fe Ni Cr Mn Al Sn Mg Ca Na Si content
(ppm) 20 600 0 10 20 300 200 200 400 600 46.0

Referring to Table 9, the Si content in SiO ₂ was found to be 46.0%, which is almost close to the theoretical value of 46.7%, and several hundred ppm of Fe, Na, Ca, Mg, and Al remained as main impurities. And the purity of SiO ₂ was 99.7%. From this, it was judged that silicic acid compounds, such as water glass, could be manufactured. In addition, it is necessary to further remove impurities in order to maximize the purity of SiO ₂ .

For additional pickling, a second pickling was performed with a separate pickling solution (15% HCl + 2.5% HF). In this case, a small amount of HF was added to minimize the loss of SiO ₂ and to maximize the efficiency of removing impurities. After the second pickling, it was dried at 100 ° C. Secondary pickling results are shown in Table 10 below.

division Cu Fe Ni Cr Mn Al Sn Mg Ca Na Si content
(ppm) One One 0 2 0 14 8 0 70 50 46.7

Referring to Table 10, SiO ₂ recovered through secondary pickling was able to obtain a final purity of 99.9%, and Cu, Fe, Al, Sn, Mg, etc. were significantly removed compared to the primary pickling. It was found that impurities can be removed by pickling.

In addition, the SiO ₂ recovered in FIG. Scanning electron microscope (SEM, JEOL JSM-T330A) Photographs, it was confirmed that the particle shape is mainly angular, the average particle size is about 100㎛.

Although the present invention has been described with reference to the embodiments, these are merely exemplary, and those skilled in the art will understand that various modifications and equivalent embodiments are possible therefrom. Accordingly, the true scope of protection of the present invention should be determined only by the appended claims.

Claims (6)

A pretreatment step of processing the bulk ferronickel slag to obtain ferronickel slag powder;
Leaching step of adding an acid to the ferronickel slag powder to separate the first filtrate containing magnesium and the insoluble precipitate containing silicon dioxide;
And a magnesia recovery step of recovering the magnesium in the form of magnesia by treating the first filtrate.
The pretreatment step includes a) coarsely pulverizing the bulk ferronickel slag, b) adding lime to the coarsely pulverized ferronickel slag, and calcining; and c) pulverizing the calcined ferronickel slag. Obtaining the ferronickel slag powder, and d) separating the iron and nickel contained in the ferronickel slag powder by magnetic force. The method of claim 1, wherein the leaching step is mixed with a ferronickel slag powder 300 to 400g per 1 liter of hydrochloric acid solution of 50% concentration, the reaction was stirred at 70 to 100 ℃ for 6 to 8 hours and then filtered to the first Separation method of silicon dioxide and magnesia from ferronickel slag, characterized in that the filtrate and the insoluble precipitate is separated. The method of claim 1, wherein the magnesia recovery step is a) adding sodium hydroxide to the first filtrate to adjust the pH to 5 to 7 to precipitate metal impurities other than magnesium, and b) the first filtrate Separating the metal impurities with the second filtrate by filtration, c) adding sodium hydroxide to the second filtrate and adjusting the pH to 9 to 11 to precipitate magnesium hydroxide, and d) the second filtration. Separating the magnesium hydroxide precipitate and the third filtrate by filtration of the liquid, and e) drying the magnesium hydroxide precipitate by calcining at 800 to 1000 ° C. to oxidize to magnesia. Separation method of silicon dioxide and magnesia from slag. The method of claim 1, wherein the silicon dioxide recovery step of recovering the silicon dioxide by treating the insoluble precipitate separated in the leaching step; separation method of silicon dioxide and magnesia from ferronickel slag. The method of claim 4, wherein the step of recovering silicon dioxide comprises the steps of: a) adding sodium hydroxide solution to the insoluble precipitate to leach silicon dioxide contained in the insoluble precipitate, and b) filtering the sodium hydroxide solution from which the silicon dioxide is leached. Separating the remaining precipitate and the fourth filtrate, and c) injecting carbon dioxide into the fourth filtrate to precipitate silicon dioxide, and d) filtering the fourth filtrate to separate the silicon dioxide precipitate. And, e) first pickling the silicon dioxide precipitate with a hydrochloric acid solution, and f) pickling the silicon dioxide precipitate with a pickling solution in which a hydrogen fluoride solution and a hydrochloric acid solution are mixed after the first pickling, followed by drying. Separation method of silicon dioxide and magnesia from ferronickel slag comprising a. A method for producing silicic acid and high-fertilizer, characterized in that the raw material is produced from silicon dioxide and magnesia separated from the ferronickel slag by the separation method of any one of claims 1 to 5.

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