JP2021123784A - Method for recovering solid content containing calcium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering a solid content containing calcium, which can be recovered more inexpensively and easily by solid-liquid separation of a non-magnetic deposit containing a calcium component after wet magnetic separation of a slurry-made steelmaking slag.
The present invention has a step of preparing a slurry containing a non-magnetic material selected by magnetic separation of steelmaking slag and a step of performing flotation of the slurry, and recovers a solid content containing calcium. Regarding the method.
[Selection diagram] Fig. 1

Description

The present invention relates to a method for recovering a solid content containing calcium.

Steelmaking slag produced in the steelmaking process (converter slag, pretreatment slag, secondary refining slag and electric furnace slag, etc.) is used in a wide range of applications including cement materials, roadbed materials, civil engineering materials and fertilizers.

Steelmaking slag includes calcium (Ca), iron (Fe), silicon (Si), manganese (Mn), magnesium (Mg), aluminum (Al), phosphorus (P), titanium (Ti), chromium (Cr), It is known that it contains elements such as sulfur (S). Of these, the element most abundant in steelmaking slag is calcium, which is used in large amounts in the steelmaking process, and often contains Fe in the next largest amount. Usually, about 20% by mass to 50% by mass of the total mass of the steelmaking slag is calcium, and about 1% by mass to 30% by mass is Fe.

Calcium in steelmaking slag is the free lime that remains as it is or is precipitated during the solidification of steelmaking slag, and the free lime is generated by reacting with water vapor or carbon dioxide in the air. Calcium (Ca (OH) ₂ ) or calcium carbonate (CaCO _{3 ), or calcium silicate (Ca 2} SiO ₄ or Ca ₃ SiO ₅ ) or calcium oxide produced by the reaction of CaO with Si, Al, etc. during coagulation. It exists in the form of iron-aluminum (Ca ₂ (Al _1-X Fe _X ) ₂ O _{5) and the like.}

Calcium carbonate and calcium oxide are the main slag forming materials in the ironmaking process and the steelmaking process during the ironmaking process, and are used as an agent for adjusting the basicity and viscosity of the slag, and as a dephosphorizing agent from molten steel. There is. In addition, calcium hydroxide obtained by adding water to calcium oxide is used as a neutralizing agent for acids and the like in the drainage process. Therefore, it is expected that the cost of steelmaking can be reduced by recovering the calcium component contained in the steelmaking slag and reusing it in the steelmaking process.

As a method for recovering the calcium component from the steelmaking slag, a slurry of steelmaking slag is wet-magnetized, and a magnetic deposit containing iron that can be reused as a steelmaking material and a non-magnetic deposit containing a calcium component are selected. A method for recovering a magnetic substance is known (Patent Document 1 and the like). The solid-liquid separation of the non-magnetic material selected by wet magnetic separation is usually performed by a method such as pressure filtration or vacuum filtration (Patent Document 2 or the like) or centrifugation (Patent Document 3 or the like). ..

JP-A-54-88894 Japanese Unexamined Patent Publication No. 2005-274107 Japanese Unexamined Patent Publication No. 2012-6771

After wet magnetic separation of the slurried steelmaking slag, recovery of the non-magnetic material containing a calcium component by solid-liquid separation is usually carried out by a method such as filtration or centrifugation.

Here, a large amount of calcium is eluted in the liquid in the slurried steelmaking slag, and this calcium reacts with carbon dioxide gas to precipitate fine particles of calcium carbonate having a particle size of about several microns. be. When the calcium component is recovered from the non-magnetic deposit after magnetic separation of the steelmaking slag by filtration, clogging is likely to occur due to the fine particles clogging the filter cloth. Therefore, if a large amount of recovery of the calcium component from the non-magnetic coating by filtration is to be performed, it is necessary to frequently replace the filter cloth, which increases the equipment cost and the running cost associated with the replacement of the filter cloth. ..

On the other hand, if the recovery of the calcium component from the non-magnetic deposit after magnetically selecting the steelmaking slag is to be performed by centrifugation, it is necessary to prepare expensive equipment and to rotate the centrifuge at high speed. Electricity costs will also be high.

In view of the above problems, the present invention recovers solids containing calcium, which can be recovered more inexpensively and easily by solid-liquid separation of non-magnetic deposits containing calcium components after wet magnetic separation of slurried steelmaking slag. Its purpose is to provide a method.

In view of the above object, the present invention has a step of preparing a slurry containing a non-magnetic material selected by magnetic separation of steelmaking slag and a step of performing flotation of the slurry, and has a solid content containing calcium. Regarding the collection method.

According to the present invention, there is provided a method for recovering a solid content containing calcium, which can be recovered more inexpensively and easily by solid-liquid separation of a non-magnetic deposit containing a calcium component after wet magnetic separation of a slurry-made steelmaking slag. NS.

FIG. 1 is a flowchart of a method for recovering a solid content containing calcium from steelmaking slag according to an embodiment of the present invention. FIG. 2A is a graph showing the amount of solids recovered as foam (mass% of total solids) by each flotation in each test of Experiment 1, and FIG. 2B is a graph showing each of Experiments 1. It is a graph which shows the recovery amount (mass% with respect to the total amount of calcium in the total solid content) of calcium recovered as foam by each flotation in a test. FIG. 3A is a graph showing the amount of solids recovered as foam (mass% with respect to total solids) by each flotation in each test of Experiment 2, and FIG. 3B is a graph showing each of Experiments 2. It is a graph which shows the recovery amount (mass% with respect to the total amount of calcium in the total solid content) of calcium recovered as foam by each flotation in a test.

FIG. 1 is a flowchart of a method for recovering a solid content containing calcium from steelmaking slag according to an embodiment of the present invention.

The type of steelmaking slag is not particularly limited as long as it is slag discharged in the steelmaking process. Examples of steelmaking slag include converter slag, pretreatment slag, secondary refining slag and electric furnace slag. Of these, since it is not necessary to separate calcium and phosphorus after recovery, the content of phosphorus in the steelmaking slag is preferably 10% by mass or less, preferably 7% by mass or less, based on the total mass of the steelmaking slag. More preferably, it is more preferably 5% by mass or less, further preferably 3% by mass or less, and particularly preferably 1% by mass or less.

[First step: heat treatment (step S110)]
In the present embodiment, it is preferable to first heat-treat the steelmaking slag.

The heating may be performed to such an extent that the iron-based oxide contained in the steelmaking slag is modified from the wustite-based oxide to the magnetite-based oxide to improve the sorting efficiency of the iron-based oxide in the subsequent magnetic separation step. For example, the heat treatment may be performed at 300 ° C. or higher and 1000 ° C. or lower for 0.01 minutes or more and 180 minutes or less.

[Second step: magnetic separation (step S120)]
Next, the heat-treated steelmaking slag is magnetically separated to remove and recover the magnetic material such as the magnetitetized iron-based oxide. The magnetic separation may be performed by a wet method or a dry method, but from the viewpoint of improving the dispersibility of the steelmaking slag particles and improving the separation efficiency between the magnetic material mainly composed of iron-based components and other non-magnetic materials. Therefore, it is preferable to perform it in a wet manner.

That is, in this step, it is preferable that after the above heat treatment, water is added to the cooled steelmaking slag to disperse the steelmaking slag to form a slurry, and then magnetic separation is performed. From the viewpoint of improving the recovery efficiency of the magnetic deposit in this step and the recovery efficiency of the non-magnetic deposit containing the calcium component in the subsequent step, the steelmaking slag may be crushed and crushed to reduce the particle size before the magnetic selection. It is preferable, and it is preferable to modify the calcium component contained in the steelmaking slag to calcium carbonate.

(Crushing and crushing)
The heat-treated steelmaking slag may be crushed by a known crusher. Further, the crushed steelmaking slag may be further pulverized by a pulverizer including a hammer mill, a roller mill, a ball mill and the like to reduce the particle size.

By crushing and crushing the steelmaking slag to reduce the particle size, the iron-based oxide contained inside the steelmaking slag is separated from _{silicon dioxide (SiO 2} ), alumina (Al ₂ O _{3), etc.} It can be made into particles, and the separation efficiency of iron-based oxides by magnetic separation can be further improved. From the above viewpoint, it is preferable that the crushing and crushing are carried out so that the maximum particle size of the steelmaking slag particles produced by crushing and crushing is about the same size as or less than the structure of the iron-based compound. For example, crushing and crushing are preferably performed so that the maximum particle size of the steelmaking slag particles is 1000 μm or less, more preferably 500 μm or less, and further preferably 250 μm or less. It is particularly preferable to carry out the process so as to be 100 μm or less.

The crushing and crushing may be carried out wet or dry, but since the steelmaking slag particles have good dispersibility in water and it is easier to reduce the particle size, they are dispersed by water addition. It is preferable to crush and crush the steelmaking slag wet.

(Carbonated)
The slurry may also be carbonated before or after crushing and grinding.

When a weak electrolyte anionic collector is used as the collector in the subsequent flotation step (step S130), calcium ions (Ca ²⁺ ions) generated by elution of the calcium component into the liquid component of the slurry are generated. If a large amount is present in the slurry, the flotation agent may become a metal soap and the recovery efficiency of steelmaking slag particles containing a calcium component may decrease. On the other hand, by modifying calcium oxide to calcium carbonate and suppressing the elution of the calcium component, it is possible to suppress the decrease in recovery efficiency due to the above-mentioned metal soap formation.

_{Specifically, carbon dioxide (CO 2} ) is blown into a slurry in which steelmaking slag is dispersed in water (aeration). As a result, calcium ions can be converted into poorly soluble calcium carbonate (CaCO _3). Incidentally, carbonate in the aqueous solution is often when pH is 10 or more is present as carbonate ion _(CO ^{3 2-),} more when the pH is lower in the bicarbonate ion ^- present as (HCO ₃₎ .. Therefore, it is preferable to adjust the pH of the slurry at this time to 10 or more in order to further increase the amount of calcium carbonate precipitated by using more of the carbonic acid introduced into the slurry by aeration as carbonic acid ions.

(Magnetic separation)
By magnetically separating a slurry obtained by performing each of the above treatments as necessary, in which steelmaking slag particles are dispersed in water, a magnetic substance containing an iron-based component and the like and a calcium component and the like are contained. It can be separated from non-magnetic particles. From the viewpoint of improving both the fluidity of the slurry and the recovery efficiency of the magnetic substance, the amount ratio of the steelmaking slag particles to water is the mass ratio of (steelmaking slag particles / water) = 1/300 or more 1 It is preferably / 2 or less, more preferably 1/200 or more and 1/5 or less, and further preferably 1/100 or more and 1/10 or less.

The magnetic separation can be performed by a method in which a slurry in which steelmaking slag particles are dispersed in water is brought into contact with the surface of a rotating drum in which a magnetic field is formed on at least a part of the surface and is rotated. Of the contacted slurries, magnetic materials such as iron-based components are captured by the surface of the rotary drum and rotate together with the rotary drum to the downstream side of the contact portion of the slurry in the rotation direction of the rotary drum. It is collected in the arranged collection unit. On the other hand, the non-magnetic substance such as the calcium component and the liquid component are separated from the rotary drum without being captured by the surface of the rotary drum. In this way, the magnetic substance containing an iron-based component and the like and the non-magnetic substance containing a calcium component and the like are separated and recovered.

From the viewpoint of easily moving the highly magnetized particles captured on the surface to the recovery part, the peripheral speed of the rotary drum during magnetic separation is preferably 0.1 m / min or more and 1000 m / min or less, preferably 1 m / min. It is more preferably 500 m / min or more, and further preferably 5 m / min or more and 300 m / min or less.

The magnet used for magnetic separation is preferably a magnet having a maximum value of magnetic flux density in the direction perpendicular to the surface of the rotary drum of 50 G or more, preferably 100 G, from the viewpoint of more reliably capturing the magnetic material such as the iron-based component. It is more preferable that the magnet is as described above. Further, from the viewpoint of making it difficult for the magnet to capture non-magnetic substances such as the calcium component and suppressing a decrease in iron concentration in the recovered material, the maximum value of the magnetic flux density in the vertical direction on the surface of the rotary drum is set. A magnet having a value of 3000 G or less is preferable, and a magnet having a value of 1500 G or less is more preferable.

The magnetic deposit thus recovered can be dehydrated and dried, then pelletized and reused as a raw material for steelmaking.

On the other hand, the non-magnetic deposit desorbed from the surface of the rotary drum may be simply solid-liquid separated by a hydrocyclone or the like. Since the overflow obtained at this time contains almost no non-magnetic particles, it can be reused for slurrying of steelmaking slag particles or wastewater.

[Third step: Froth flotation (step S130)]
In this step, flotation is performed on the slurry of the non-magnetic deposit thus obtained.

The non-magnetic deposit (or hydrocyclone underflow) desorbed from the surface of the rotary drum is a concentrated slurry containing a calcium component. In this step, first, the concentrated slurry is hydrated (repulped) to adjust the slurry concentration.

Then, a collecting agent and optionally other additives including a foaming agent and a pH adjuster are added to the slurry and stirred (conditioning), and then air bubbles are introduced into the slurry. The solid component in the slurry adheres to the surface of the bubbles by binding or interaction with the collecting agent and floats on the surface of the slurry together with the bubbles. By recovering the bubbles (floss) of bubbles to which the solid component is attached that floats on the surface, the solid component in the slurry can be separated from the liquid component and recovered. The solid content obtained by solid-liquid separation of the recovered foam is a solid content containing a high concentration of calcium.

(Recovery agent)
The above-mentioned collecting agent may be any collecting agent capable of recovering the calcium component, and may be an inorganic collecting agent or an organic collecting agent, but is an organic collecting agent. Is preferable.

In particular, in the present embodiment, it is preferable to use a weak electrolyte anionic scavenger (hereinafter, also simply referred to as “first scavenger”) as the scavenger, and further, a strong electrolyte anionic scavenger. It is more preferable to use an ionic scavenger (hereinafter, also simply referred to as “second scavenger”) in combination.

In the present specification, when a compound is a weak electrolyte, the acid dissociation constant (pka) of the compound (when the compound has a plurality of acid dissociation constants, the first acid dissociation constant (pka ₁ )). ) Is 2 or more. Similarly, when a compound is a strong electrolyte, the acid dissociation constant (pka) of the compound (or the first acid dissociation constant (pka ₁ ) when the compound has multiple acid dissociation constants) is less than 2. Means that

(First collector)
The first catching agent is a compound of a weak electrolyte having a functional group adsorbing on calcium and a hydrophobic group. Examples of the functional group adsorbed on calcium include a carboxy group and a sulfonic acid group. The hydrophobic group can be, for example, a saturated or unsaturated alkyl group having 6 to 18 carbon atoms. When the hydrophobic group has 6 or more carbon atoms, the first catching agent is adsorbed to the bubbles satisfactorily. When the number of carbon atoms of the hydrophobic group is 18 or less, the first catching agent can be sufficiently dissolved in the liquid component (water) of the slurry. The first collector may be these acids (higher fatty acids or alkyl sulfonic acids), but may also form salts. The counterion when it is a salt may be sodium ion or the like.

The first collecting agent is preferably a saturated or unsaturated higher fatty acid or a salt thereof, and more preferably a saturated or unsaturated higher fatty acid having 12 or more and 18 or less carbon atoms or a salt thereof. It is more preferably an unsaturated higher fatty acid having 12 or more and 18 or less carbon atoms or a salt thereof, and particularly preferably oleic acid or a salt thereof.

In these first collectors, the functional group forms a chemical bond with calcium to firmly capture steelmaking slag particles containing a calcium component. Therefore, by using these first collectors, the recovery efficiency of the steelmaking slag particles containing the calcium component in this step can be sufficiently increased.

The amount of the first catching agent added to the slurry containing the non-magnetic deposit is such that the steelmaking slag particles can be sufficiently recovered and micelles are not formed by the first collecting agent (less than the critical micelle concentration). It is preferable, for example, 1 ppmv or more and 1000 ppmv or less.

(Second collector)
The second scavenger is a compound of a strong electrolyte that can electrostatically interact with the calcium component and co-adsorb to the first scavenger and calcium. The second collector can be a sulfate ester compound such as alkylbenzene sulfonic acid or a salt thereof. The counterion when it is a salt may be sodium ion or the like.

The alkylbenzene sulfonic acid or a salt thereof is preferably an alkylbenzene sulfonic acid having 6 or more and 18 or less carbon atoms or a salt thereof, more preferably an alkylbenzene sulfonic acid having 12 or more and 18 or less carbon atoms or a salt thereof, and dodecylbenzene. More preferably, it is a sulfonic acid (DBS) or a salt thereof.

When the first collector forms a salt with calcium eluted from the surface of the steelmaking slag particles to form a metal soap, it may adhere to the surface of the bubbles and cannot float on the surface of the slurry. Further, when the first collecting agent is consumed by the metal soap formation, the recovery efficiency in this step is lowered. Furthermore, even if the first catching agent is adsorbed on the calcium existing on the surface of the steelmaking slag particles, if the adsorbed calcium is eluted, the first collecting agent is also removed from the steelmaking slag particles. Since they are separated, it may not be possible to stably collect steelmaking slag particles.

On the other hand, the second collector forms a stable adsorption layer on the surface of the steelmaking slag particles and suppresses the elution of calcium from the surface of the steelmaking slag particles. As a result, the second collecting agent suppresses the formation of metal soap by the above-mentioned eluted calcium and the desorption of the first collecting agent from the steelmaking slag due to the above-mentioned elution of calcium, and the calcium component in this step is suppressed. It is considered that the recovery efficiency of the steelmaking slag particles contained therein is maintained.

Further, the second collecting agent suppresses the amount of the first collecting agent used by suppressing the formation of metal soap, and makes it possible to recover the steelmaking slag particles in this step at low cost.

The amount of the second catching agent added to the slurry containing the non-magnetic deposit is such that the steelmaking slag particles can be sufficiently recovered and micelles are not formed by the second collecting agent (less than the critical micelle concentration). It is preferable, for example, 1 ppmv or more and 1000 ppmv or less.

Further, the amount of the second collecting agent added is preferably substantially the same as the amount of the first collecting agent added. Specifically, the first collecting agent and the second collecting agent are added. In terms of volume ratio, the amount ratio with (1st catching agent / 2nd catching agent) is preferably 1/4 or more and 4/1 or less, and 1/3 or more and 3/1 or less. More preferably, it is more preferably 1/2 or more and 2/1 or less.

(Other collection agents)
In addition, in this embodiment, the above-mentioned first collection agent or other collection agent different from the second collection agent may be used, and the above other collection agent may be used as the first collection agent. Alternatively, it may be used in combination with a second collecting agent.

Examples of the other collecting agents include saturated or unsaturated alkylamines having 6 to 18 carbon atoms or salts thereof, such as dodecyl ammonium acetate (DAA). However, since a cationic scavenger such as DAA is often expensive and the scavenging efficiency is lower than that of the first scavenger, it is possible to use the first scavenger described above in this embodiment. preferable.

(Coagulant)
In this step, before adding the first collecting agent and the second collecting agent, the cationic polymer flocculant (hereinafter, also simply referred to as “aggregating agent”) is added to the slurry containing the non-magnetic deposit. It is preferable to add it.

The flocculant can aggregate calcium carbonate. Therefore, by adding a coagulant in advance to the slurry containing the non-magnetic deposit, the first catching agent is adsorbed on the steelmaking slag particles having an appropriate size due to the coagulation and floats together with the bubbles, so that the first catching agent is formed. Even if the amount of the collector added is smaller, the steelmaking slag particles containing the calcium component can be sufficiently recovered.

The amount of the aggregating agent added to the slurry containing the non-magnetic material may be such that the steelmaking slag particles appropriately agglomerate and the recovery efficiency by the first collecting agent is increased. Specifically, the particle size of the steelmaking slag particles contained in the non-magnetic material, which usually has a particle size of less than 10 μm, may be added to such an extent that the particle size is 10 μm or more, and is, for example, 0.01 ppmv or more and 10000 ppmv or less. Is more preferable, 0.1 ppmv or more and 1000 ppmv or less is more preferable, and 1 ppmv or more and 100 ppmv or less is further preferable.

(Other additives)
In addition to these, a foaming agent, a pH adjuster, and the like can be added to the slurry containing the non-magnetic material.

The foaming agent promotes the generation of bubbles and stabilizes the bubbles formed on the surface of the slurry. The foaming agent may be any known foaming agent such as an alcohol having 1 to 8 carbon atoms and a ketone having 1 to 8 carbon atoms, and may be, for example, methanol, ethanol, propanol, butanol, or methyl isobutyl ketone ( MIBK), methyl isobutyl carbinol (MIBC) and the like are preferably used. The amount of the foaming agent added to the slurry containing the non-magnetic material is preferably 1 ppm or more and 10000 ppm or less in terms of molar amount.

The pH adjuster adjusts the pH of the slurry. The second collector electrostatically interacts with the calcium component present on the surface of the steelmaking slag particles and adsorbs them on the steelmaking slag particles. In order to cause this electrostatic adsorption, it is desirable that the zeta potential of the calcium component (particularly calcium carbonate) is positive. From this point of view, especially when a second collector is used, it is preferable to adjust the pH of the slurry containing the non-magnetic substance to an alkaline range of 7 to 14 with a pH adjuster, and to 9 to 12. It is more preferable to adjust.

(De-Ca ²⁺ ion)
^{In this step, calcium ions (Ca 2+} ions) generated by elution of the calcium component into the liquid component of the slurry may be precipitated as poorly soluble calcium carbonate.

The precipitation method is not particularly limited, but for example, carbon dioxide (CO ₂ ) may be blown into the slurry (aeration). Incidentally, carbonate in the aqueous solution is often when pH is 10 or more is present as carbonate ion _(CO ^{3 2-),} more when the pH is lower in the bicarbonate ion ^- present as (HCO ₃₎ .. Therefore, it is preferable to adjust the pH of the slurry at this time to 10 or more in order to further increase the amount of calcium carbonate precipitated by using more of the carbonic acid introduced into the slurry by aeration as carbonic acid ions.

Precipitation of calcium ions may occur at any time, such as before the addition of the catching agent, after the addition of the collecting agent and before conditioning, after conditioning and before flotation. If the carbonate ions and hydrogen carbonate ions that have increased in the slurry due to aeration are adsorbed on the calcium sites of calcium carbonate existing on the surface of the steelmaking slag particles, which hinders the adsorption of the collected material. , The above exposure does not have to be performed.

(Floth flotation)
The method of flotation is not particularly limited, and it can be performed by a known flotation method including an air self-sufficient type and an air blowing type. Of these, the air-blown type is preferable, such as the column type in which air is blown from the spurger arranged at the bottom of the column, and the agitea type in which air is blown from the impeller shaft and at the same time the impeller is rotated at high speed to generate air bubbles. The formula is more preferred.

The bubbles to which the steelmaking slag particles containing the calcium component are attached and float on the surface of the slurry are preferably microbubbles having an average diameter of 0.1 μm or more and 1000 μm or less, and preferably 1 μm or more and 200 μm or less. Since the microbubbles have a fine volume, the ascending rate is slow, they are difficult to bond with each other, and the surface area is large, so that steelmaking slag particles containing a calcium component can be efficiently adhered.

From the viewpoint of improving the recovery efficiency by the above-mentioned collector, the slurry in which the steelmaking slag particles containing the calcium component are recovered by flotation is preferably a slurry having a particle size d90 of the steelmaking slag particles of 500 μm or less, preferably 200 μm or less. It is more preferable that the slurry is 100 μm or less, and more preferably 100 μm or less. The particle size d90 of the steelmaking slag particles can be adjusted by the degree of crushing or crushing of the steelmaking slag particles.

Further, from the viewpoint of improving the recovery efficiency by flotation, the slurry preferably has a slurry concentration of 0.5 w / v% or more and 20 w / v% or less, and 1 w / v% or more and 10 w / v% or less. A slurry is more preferable, and a slurry of 2 w / v% or more and 5 w / v% or less is further preferable. The slurry concentration can be adjusted by adding water or the like, if necessary.

(collect)
After that, the bubbles floating on the surface of the slurry are collected, and the collected bubbles are solid-liquid separated by a known method such as coagulation precipitation, whereby the solid content containing calcium can be recovered. The recovery method is not particularly limited, and the upper layer of the slurry may be overflowed, bubbles may be scooped up, or the slurry may be sucked into a decompression container by a pipe or the like.

On the other hand, the unrecovered residue is reused for slurrying of steelmaking slag particles or wastewater after repeated addition of a catching agent and other additives, conditioning, flotation, and recovery as necessary. Can be done.

(effect)
As described above, in the present embodiment, the recovery efficiency of the steelmaking slag particles containing the calcium component can be remarkably improved by using the anionic catching agent (first catching agent) of the weak electrolyte. Further, in the present embodiment, by using the anionic scavenger (second scavenger) of the strong electrolyte, the metal soap formation of the first scavenger is suppressed and the first scavenger is used. The amount used can be reduced. Further, in the present embodiment, the steelmaking slag particles are agglomerated in advance with a flocculant and then flotation is performed to improve the recovery efficiency of the steelmaking slag particles containing a calcium component, and the first catching agent is used. The amount can also be reduced. Further, by reducing the amount of the first collecting agent used in this way, it becomes possible to recover the steelmaking slag particles containing the calcium component at low cost.

Hereinafter, the present invention will be described in more detail with reference to Examples. It should be noted that these examples do not limit the scope of the present invention to the specific methods described below.

[Experiment 1]
Steelmaking slag having the component ratios shown in Table 1 was prepared. The components of the steelmaking slag were measured by fluorescent X-ray (XRF) analysis.

The steelmaking slag shown in Table 1 was pulverized so as to have a diameter of 5 mm or less, and then heated at 750 ° C. for 10 minutes. After heating, it was air-cooled until it reached room temperature. Then, 0.2 L of water was added to 20.00 g of the heat-treated steelmaking slag, and wet pulverization was performed with a ball mill so that the maximum particle size of the steelmaking slag particles was 100 μm or less.

1.8 L of water was added to the slurry in which the steelmaking slag particles were dispersed in water and magnetically separated by a drum type magnetic separator. The air core magnetic field strength of the drum was 500 G, and the flow rate of the slurry was 6.83 L / min. After magnetic separation, the rotary drum was rinsed with 0.5 L of water. By this magnetic separation, 5.91 g of solid content (magnetic deposit) was recovered.

(Test 1-A)
The following experiment was carried out using 1 L of the slurry containing a non-magnetic substance that was detached without being captured by the surface of the rotary drum.

As a scavenger, 30 ppmv of sodium oleate (first scavenger) and 20 ppmv of sodium dodecylbenzenesulfonate (second scavenger) were added to the slurry. After that, the slurry was put into an agitate flotation machine, the impeller was rotated at 1000 rpm for 5 minutes to perform conditioning, and then the air flow rate was set to 6 to 14 L / min, and the flotation by microbubbles was performed for 5 minutes. .. The amount of each element was measured by weighing and XRF analysis for the solid content obtained by collecting, filtering and drying the floating foam. The solid content recovered by the first flotation is referred to as "1-F1-A".

To the residual slurry after collecting the foam, 30 ppmv of sodium oleate (first collector) and 20 ppmv of sodium dodecylbenzenesulfonate (second collector) were added, and the same flotation was performed. The beneficiation was carried out for 5 minutes, and the flotation was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. The solid content recovered by the second flotation is referred to as "1-F2-A".

Further, the same flotation was carried out, and the amount of each element was measured by collecting, filtering, drying and XRF analysis of the floating foam. The solid content recovered by the third flotation is referred to as "1-F3-A". In addition, the slurry residue not recovered by the third flotation was also filtered, dried, and weighed and the component amount of each element was measured by XRF analysis. The slurry residue is referred to as "1-sink-A".

(Test 1-B)
The following experiment was carried out using another 1 L of the slurry containing a non-magnetic substance that was detached without being captured by the surface of the rotary drum.

As a scavenger, 100 ppmv of dodecyl ammonium acetate (cationic scavenger) was added to the slurry. Then, the slurry was put into an agitate flotation machine, and the impeller was rotated at 1000 rpm for 5 minutes for conditioning. Then, carbon dioxide (CO ₂ ) was blown into the slurry. The carbon dioxide was blown in for 21 minutes at a flow rate of 0.24 nL / min. After that, the air flow rate was set to 6 to 20 L / min, and flotation by microbubbles was performed for 7 minutes. The amount of each element was measured by weighing and XRF analysis for the solid content obtained by collecting, filtering and drying the floating foam. The solid content recovered by the first flotation is referred to as "1-F1-B".

To the residual slurry after collecting the foam, 30 ppmv of dodecyl ammonium acetate (cationic collector) was added, and the same flotation was performed for 5 minutes to collect, filter, dry, and float the foam. The amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the second flotation is referred to as "1-F2-B".

Further, 30 ppmv of dodecylammonium acetate (cationic collector) was added to the residual slurry after collecting the foam, and the same flotation was performed for 4 minutes to collect, filter, and dry the floating foam. , And the component amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the third flotation is referred to as "1-F3-B".

Further, 30 ppmv of dodecylammonium acetate (cationic collector) was added to the residual slurry after collecting the foam, and the same flotation was carried out for 5 minutes to collect, filter, and dry the floating foam. , And the component amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the fourth flotation is referred to as "1-F4-B".

Further, 50 ppmv of dodecylammonium acetate (cationic collector) was added to the residual slurry after collecting the foam, and the same flotation was carried out for 4 minutes to collect, filter and dry the floating foam. , And the component amount of each element was measured by weighing and XRF analysis. The solid content recovered by the fifth flotation is referred to as "1-F5-B". In addition, the slurry residue not recovered by the fifth flotation was also filtered, dried, and weighed and the component amount of each element was measured by XRF analysis. The slurry residue is referred to as "1-sink-B".

(result)
The amount of solids recovered (mass% of total solids) and the amount of calcium recovered (total of calcium in total solids) for the solids recovered as foam and the solids obtained from the slurry residue in each test. Table 2 shows the amount of the collected agent added (sodium oleate is referred to as “NaOl”, sodium dodecylbenzenesulfonate is referred to as “NaDBS”, and dodecylammonium acetate is referred to as “DAA”). ..

Further, in each test, the amount of solids recovered as foam by each flotation (mass% with respect to total solids) is shown in FIG. 2A, and the amount of calcium recovered as foam by each flotation (mass%). (% by mass based on the total amount of calcium in the total solid content) is shown in FIG. 2B, respectively.

As shown in Table 2, FIG. 2A and FIG. 2B, the solid content containing calcium could be recovered from the slurry containing the non-magnetic deposit selected by the magnetic separation of the steelmaking slag by flotation.

In particular, when sodium oleate (first collector) and sodium dodecylbenzenesulfonate (second collector) are used as the flotation agent (Test 1-A), dodecyl ammonium acetate (cationic) is used as the flotation agent. More solids can be recovered and more solids can be recovered with less amount of scavenger and fewer flotations than when ionic scavenger) was used (Test 1-B). The calcium component could be recovered.

[Experiment 2]
Steelmaking slag having the component ratios shown in Table 3 was prepared. The components of the steelmaking slag were measured by fluorescent X-ray (XRF) analysis.

The steelmaking slag shown in Table 1 was classified so that the maximum particle size was 25 mm or less, and then heated at 750 ° C. for 10 minutes. After heating, it was air-cooled until it reached room temperature. Then, the heat-treated steelmaking slag was dry-pulverized with a ball mill so that the diameter was 100 μm or less.

The same amount of water was added to the crushed steelmaking slag particles to form a slurry, which was then added so that the ratio of solid content to water was 1/50 by mass ratio, and magnetically separated by a drum-type magnetic separator. .. The air core magnetic field strength of the drum was 3500 T, and the flow rate of the slurry was 6.83 L / min. By this magnetic separation, an amount of solid content (magnetic deposit) corresponding to 60% by mass of the steelmaking slag particles was recovered.

Water was added so that the ratio of the solid content to water was 1/100 of the mass ratio of 20.00 g of the slurry containing the non-magnetic substance that was detached without being trapped on the surface of the rotary drum. The following experiment was carried out using the slurry containing the non-magnetic material thus obtained.

(Test 2-A)
As a scavenger, 20 ppmv of sodium oleate (first scavenger) and 20 ppmv of sodium dodecylbenzenesulfonate (second scavenger) were added to the slurry. Then, the slurry was put into an agitate flotation machine, the impeller was rotated at 1000 rpm for 5 minutes to perform conditioning, and then the air flow rate was set to 6 to 8 L / min, and the flotation by microbubbles was performed for 5 minutes. .. The amount of each element was measured by weighing and XRF analysis for the solid content obtained by collecting, filtering and drying the floating foam. The solid content recovered by the first flotation is referred to as "2-F1-A".

To the residual slurry after collecting the foam, 20 ppmv of sodium oleate (first collector) and 20 ppmv of sodium dodecylbenzenesulfonate (second collector) were added, and the same flotation was performed. The beneficiation was carried out for 5 minutes, and the flotation was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. The solid content recovered by the second flotation is referred to as "2-F2-A".

Further, 30 ppmv of sodium oleate (first collector) and 30 ppmv of sodium dodecylbenzenesulfonate (second collector) were added to the residual slurry after collecting the foam, and the same was performed. Floth flotation was carried out for 5 minutes, and the floating foam was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. The solid content recovered by the third flotation is referred to as "2-F3-A".

Further, 30 ppmv of sodium oleate (first collector) and 30 ppmv of sodium dodecylbenzenesulfonate (second collector) were added to the residual slurry after collecting the foam, and the same was performed. Floth flotation was carried out for 5 minutes, and the floating foam was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. The solid content recovered by the fourth flotation is referred to as "2-F4-A". In addition, the slurry residue not recovered by the fourth flotation was also filtered, dried, and weighed and the component amount of each element was measured by XRF analysis. The slurry residue is referred to as "2-sink-A".

(Test 2-B)
As a cationic polymer flocculant, 10 ppmv of "Sunflock C-009P" manufactured by Sanyo Chemical Industries, Ltd. was added to the slurry, and then 20 ppmv of sodium oleate (first collector) was added as a collector. Added to the slurry. Then, the slurry was put into an agitate flotation machine, the impeller was rotated at 1000 rpm for 5 minutes to perform conditioning, and then the air flow rate was set to 8 L / min, and the flotation by microbubbles was performed for 5 minutes. At this time, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry as a foaming agent. The amount of each element was measured by weighing and XRF analysis for the solid content obtained by collecting, filtering and drying the floating foam. The solid content recovered by the first flotation is referred to as "2-F1-B".

The same flotation was carried out for 5 minutes except that 20 ppmv of sodium oleate (first collector) was added to the residual slurry after collecting the foam to set the air flow rate to 18 to 20 L / min. , Floth flotation was recovered, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the second flotation is referred to as "2-F2-B".

Further, 30 ppmv of sodium oleate (first collector) was added to the residual slurry after collecting the foam, and the same flotation as in the second flotation was performed for 5 minutes to float. The foam was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the third flotation is referred to as "2-F3-B".

Further, 20 ppmv of sodium oleate (first collector) was added to the residual slurry after collecting the foam, and the same flotation as in the second flotation was performed for 5 minutes to float. The foam was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the fourth flotation is referred to as "2-F4-B".

Further, 10 ppmv of sodium oleate (first collector) was added to the residual slurry after collecting the foam, and the same flotation as in the second flotation was performed for 3 minutes to float. The foam was collected, filtered, dried, and the amount of each element was measured by weighing and XRF analysis. During the flotation, 20 drops of methylisobutylcarbinol (foaming agent) was added to the slurry. The solid content recovered by the fifth flotation is referred to as "2-F5-B". In addition, the slurry residue not recovered by the fifth flotation was also filtered, dried, and weighed and the component amount of each element was measured by XRF analysis. The slurry residue is referred to as "2-sink-B".

(result)
The amount of solids recovered (mass% of total solids) and the amount of calcium recovered (total of calcium in total solids) for the solids recovered as foam and the solids obtained from the slurry residue in each test. Table 4 shows the amount of the collected agent added (sodium oleate is referred to as “NaOl”, sodium dodecylbenzenesulfonate is referred to as “NaDBS”, and dodecylammonium acetate is referred to as “DAA”). ..

Further, in each test, the amount of solids recovered as foam by each flotation (mass% with respect to total solids) is shown in FIG. 3A, and the amount of calcium recovered as foam by each flotation (mass%). (Mass% based on the total amount of calcium in the total solid content) is shown in FIG. 3B, respectively.

As shown in Table 4, FIG. 3A and FIG. 3B, sodium oleate (first flotation agent) and sodium dodecylbenzenesulfonate (second flotation agent) are used in combination as a flotation agent (Test 2-A). ), And with a smaller number of flotations, more solids could be recovered and more calcium components could be recovered.

In addition, if a cationic polymer flocculant is added to the slurry before the collection agent is added (Test 2-B), more solids can be recovered with a smaller number of flotations, and more solids can be recovered. , I was able to recover more calcium components.

The method for recovering a solid content containing calcium according to the present invention can be recovered more inexpensively and easily by solid-liquid separation of a non-magnetic deposit containing a calcium component after wet magnetic separation of a slurry-made steelmaking slag, and thus in steelmaking. It is useful as a method for recovering calcium resources.

Claims (7)

The process of preparing a slurry containing a non-magnetic material selected by magnetic separation of steelmaking slag, and
A step of performing flotation on the slurry and
A method for recovering a solid content containing calcium. The method for recovering a solid content containing calcium according to claim 1, wherein an anionic scavenger of a weak electrolyte is used as a scavenger in the step of performing flotation. The method for recovering a solid content containing calcium according to claim 2, wherein an anionic scavenger of a strong electrolyte is further used as a scavenger in the step of performing flotation. The method for recovering a solid content containing calcium according to claim 2 or 3, further using a cationic polymer flocculant as a collecting agent in the step of performing flotation. The calcium-containing solid content according to any one of claims 1 to 4, wherein the slurry is a slurry containing the non-magnetic substance selected by magnetic separation after carbonating the slurry containing the steelmaking slag. Collection method. The method for recovering a solid content containing calcium according to any one of claims 1 to 5, wherein the slurry is a slurry having a particle size d90 of 500 μm or less. The method for recovering a solid content containing calcium according to any one of claims 1 to 6, wherein the slurry is a slurry having a slurry concentration of 0.5 w / v% or more and 20 w / v% or less.

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