WO2022032726A1

WO2022032726A1 - Foam separation method for magnesium hydroxide colloidal solution

Info

Publication number: WO2022032726A1
Application number: PCT/CN2020/111355
Authority: WO
Inventors: 王丽; 张烨; 孙伟; 徐芮; 胡岳华; 高建德
Original assignee: 中南大学
Priority date: 2020-08-08
Filing date: 2020-08-26
Publication date: 2022-02-17
Also published as: CN111874926B; CN111874926A

Abstract

A foam separation method for a magnesium hydroxide colloidal solution. The method comprises: adding an appropriate amount of a modifier to a magnesium hydroxide colloidal solution, and performing stirring and pulp conditioning; adding a foaming agent to magnesium hydroxide pulp and filling with a gas, and standing for several hours to obtain an upper layer and a clarified water layer, the upper layer being magnesium hydroxide, and foam being directly dried to obtain a magnesium hydroxide product. The method can achieve high-efficiency separation between magnesium hydroxide and water in the magnesium hydroxide colloidal solution, and also solves the problem of difficult filtration of magnesium hydroxide colloids in the conventional magnesium hydroxide precipitation process.

Description

A kind of method of magnesium hydroxide colloidal solution foam separation

technical field

The invention relates to a method for recycling magnesium hydroxide resources, in particular to a method for separating foams of magnesium hydroxide colloidal solution, belonging to the technical field of comprehensive utilization of magnesium resources.

Background technique

Magnesium is one of the most abundant light metal elements on earth. Magnesium is abundant in abundance, with an abundance of 2% in the earth's crust. Magnesium is an important material for the aviation industry. Magnesium alloys are good lightweight structural materials and are widely used in industrial sectors such as space technology, aviation, automobiles and instrumentation. Magnesium is also used to manufacture photographic and optical instruments. As a strong reducing agent, Magnesium can also be used in the production of titanium, zirconium, beryllium, uranium and hafnium; magnesium fertilizer can promote the absorption and utilization of phosphorus by plants, and the growth of magnesium-deficient plants tends to stagnate. Magnesium is a basic material that occupies an important position in people's lives.

my country ranks first in the world in reserves of magnesium resources, accounting for 22.5% of the world's total reserves, including magnesium ore resources, salt lake magnesium resources and marine magnesium resources. At present, magnesium ore resources are mainly magnesite and dolomite. my country has proven magnesite reserves of 3.4 billion tons and dolomite reserves of more than 4 billion tons. The four salt lake areas in my country are rich in magnesium salt resources. Among them, 33 brine lakes, semi-dry salt lakes and dry salt lakes in the Qaidam Basin have reserves of 6.003 billion tons of magnesium salt resources. The reserves amount to 6.003 billion tons, of which the magnesium salt reserves in the Qaidam Basin account for 99% of the total amount of magnesium salts identified in the country, ranking first in the country, and it is an important source of magnesium salt production.

In recent years, scholars at home and abroad have carried out a lot of research on the development and utilization of magnesium resources in solution. At present, the research on solution magnesium resources mostly focuses on the production of various magnesium salt products, including magnesium sulfate, magnesium hydroxide, magnesium oxide, magnesium carbonate, magnesium oxalate and hydrotalcite materials. Among them, the production process of traditional magnesium hydroxide products mostly adopts the sodium hydroxide precipitation method to directly precipitate magnesium ions. Although the process is simple, the particle size of the precipitated magnesium hydroxide is extremely fine (the particle size is generally below 100nm), and there is hydration It is easy to form magnesium hydroxide hydrate, so that it can be stably and uniformly dispersed in the solution to form a magnesium hydroxide colloidal solution. The colloidal solution is different from other conventional solid slurry systems, and the magnesium hydroxide has poor sedimentation or filtration performance. In view of this problem, although crystalline Mg(OH) ₂ can be obtained by modifying and controlling the precipitation conditions to improve its filtration performance, the complexity of the process flow increases, and industrial production is not used. Therefore, for the magnesium hydroxide colloidal solution, it is urgent to develop a process flow with simple process and little environmental pollution, so as to realize the high-efficiency solid-liquid separation of the magnesium hydroxide colloidal solution, and then realize the comprehensive recovery and utilization of magnesium resources.

technical problem

In the prior art, the magnesium hydroxide precipitation generated by the traditional direct precipitation method to produce magnesium hydroxide is easy to generate colloids, and the problems such as poor natural settling performance and filtration performance are used for the recovery of solution magnesium resources. The object of the present invention is to provide A method for foam separation of magnesium hydroxide colloidal solution.

technical solutions

In order to achieve the above technical purpose, the present invention provides a method for foam separation of magnesium hydroxide colloidal solution, which is characterized by comprising the following steps.

Step 1) Add a modifier to the magnesium hydroxide colloidal solution and mix to obtain a mixed solution; the modifier is an amine modifier of formula 1, a sulfonic acid modifier of formula 2, and a At least one of the sulfuric acid-based modifier of structural formula 3 and the carboxylic acid-based modifier of structural formula 4.

.

Said R ₁ to R ₄ are independently C ₁₀ to C ₃₀ saturated hydrocarbon groups or hydrocarbon groups with 1 to 3 unsaturated bonds, or six-membered ring hydrocarbon groups.

The M is H, Na, K or NH ₄ ⁺ .

The A is -OH, -ONa, -OK, -ONH ₄ ⁺ , -NOH or -OR; the R is a C ₁ -C ₆ alkyl group.

Step 2) Add a foaming agent to the mixed solution and fill with gas to conduct gas-solid-liquid three-phase treatment.

Step 3) The aerated mixed solution is allowed to stand and layer to obtain an upper layer of magnesium hydroxide and a water layer.

The particle size of magnesium hydroxide formed by the precipitation method is extremely fine (below 100nm), and because of its hydroxide characteristics and nanoscale size characteristics, it is easy to form hydration, and it is easy to form a stable magnesium hydroxide colloidal solution; it is difficult to pass natural Sedimentation or filtration methods achieve separation of colloidal particles from aqueous solutions.

In order to solve the technical problem that the magnesium hydroxide colloid is difficult to effectively separate, the method of the present invention realizes the hydrogenation by adding the modifier and the foaming agent of the stated content to the magnesium hydroxide colloid solution, inflating after mixing, and standing for stratification. Efficient separation of magnesium oxide and water. In the present invention, under the three-phase (gas-solid-liquid) synergistic action of the modifier and gas, the magnesium hydroxide colloid can destroy the hydrated structure of magnesium hydroxide, and modify the surface of magnesium hydroxide to increase its surface Hydrophobicity, form hydrophobic aggregates, and make magnesium hydroxide aggregate to the upper layer, so as to separate from the water phase, and effectively realize the high-efficiency solid-liquid separation of magnesium hydroxide colloid and the recovery of precipitation. The invention benefits from the chemical and physical synergy of the agent and the gas, and can separate and recover the magnesium hydroxide in the colloidal solution, thereby realizing the efficient recovery of the magnesium ions in the solution and overcoming the magnesium hydroxide in the traditional precipitation process. The technical problems of colloid filtration and recovery are difficult, and the process is simplified, the process time is shortened, and the adverse impact on the environment is reduced.

The technical scheme of the present invention is to add an appropriate amount of modifier and foaming agent to the colloidal solution of magnesium hydroxide, stir and adjust slurry and aerate, and utilize the interaction between magnesium hydroxide, modifier and air bubbles to inhibit hydration and form hydrophobicity. Aggregates to achieve high-efficiency solid-liquid separation of magnesium hydroxide colloids. The technical scheme of the present invention innovatively utilizes the modifier for the modification of magnesium hydroxide and its hydrate, thereby solving the problem of selective separation of magnesium hydroxide and water in the magnesium hydroxide colloid. The technical scheme of the invention simplifies the process, shortens the process time, reduces the adverse impact on the environment, and overcomes the problems of poor natural sedimentation performance and filtration performance of magnesium hydroxide colloid produced by the traditional precipitation method.

In the present invention, the magnesium hydroxide colloidal solution may be a colloidal solution formed by any existing means. For example, the magnesium hydroxide colloidal solution is obtained by a traditional precipitation method, and the alkali metal hydroxide is added to a solution containing magnesium ions such as salt lake brine and salicylic salt solution.

Preferably, the added amount of the alkali metal hydroxide is 1 to 1.2 times the theoretical molar amount of the alkali metal hydroxide required to convert all the magnesium ions in the magnesium ion-containing solution into magnesium hydroxide. Alkali metal hydroxides are common strong bases in the art, such as sodium hydroxide, potassium hydroxide and the like.

In the magnesium hydroxide colloidal solution, the particle size of the magnesium hydroxide is below 100 nm, preferably 30 nm-100 nm.

In the magnesium hydroxide colloidal solution of the present invention, the content of magnesium hydroxide is not required, and the method of the present invention can be used to achieve efficient and high-selective separation when a stable colloidal solution is formed. For example, the magnesium hydroxide concentration in the magnesium hydroxide colloidal solution is not higher than 80 g/L.

In the present invention, in step (1), the pH of the magnesium hydroxide colloid solution is controlled to be 8-11.50; preferably 9-11.50; more preferably 9-10. The study found that controlling under the preferred pH conditions can help to further improve the gas-solid-liquid three-phase interaction between the modifier, magnesium hydroxide particles and bubbles, and help to further improve the treatment effect, and Reduce disposal costs and avoid environmental pressures.

The present invention innovatively utilizes the modifier to modify the colloid formed by magnesium hydroxide hydrate, and combines the gas-solid-liquid three-phase action to achieve high-selectivity separation of magnesium hydroxide and water. The research of the present invention also found that controlling the type of the modifier can help to further improve the effect, help to further improve the separation selectivity of magnesium hydroxide and water in the hydroxide colloid, and improve the recovery of magnesium hydroxide. Not only that, but also can significantly improve the processing efficiency.

In the modifier of the present invention, the R ₁ to R ₄ can be saturated hydrocarbon groups of C ₁₀ to C ₃₀ , preferably, the saturated alkyl groups are straight-chain saturated alkyl groups. For example, the R ₁ ~R ₄ can be decyl, n-undecyl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl , n-heptadecyl, n-octadecyl, n-nonadecyl, n-eicosyl, n-hecosyl, n-docosyl, n-docosyl, n-docosyl alkyl, n-pentacosyl, n-hexadecyl, n-heptacosyl, n-octacosyl, n-nonacosyl or n-triaconyl.

In addition, the R ₁ to R ₄ may also be hydrocarbon groups with double bonds, preferably straight-chain hydrocarbon groups with double bonds. Preferably, the double bond is formed by any adjacent carbon in the 2nd to 30th positions. Preferably, the number of the double bonds is 1 to 3. When the number of double bonds is 2 or 3, the double bonds preferably do not share carbon atoms.

In addition, the R ₁ to R ₄ may also be a six-membered ring hydrocarbon group, and the six-membered ring hydrocarbon group may be a saturated ring hydrocarbon group or a partially unsaturated ring hydrocarbon group.

Preferably, the sulfonic acid modifier includes at least one of sodium petroleum sulfonate, sodium dodecyl sulfonate, sodium octadecyl sulfonate, and sodium hexadecyl sulfonate.

Preferably, the sulfuric acid modifier is at least one of sodium lauryl sulfate, sodium hexadecyl sulfate, and sodium octadecyl sulfate.

Preferably, the carboxylic acid modifiers include oleic acid, linoleic acid, linolenic acid, lauric acid, myristic acid, capric acid, palmitic acid, stearic acid, naphthenic acid, hydroxamic acid, oxidized paraffin soap , at least one of tall oil, tall oil soap and sodium oleate. The research found that the preferred carboxylic acid modifier can obtain good separation effect at a lower dosage.

Preferably, the amine modifier includes at least one of dodecylamine, tetradecylamine, hexadecylamine, octadecylamine and dodecylamine. The research of the present invention unexpectedly found that the use of the amine modifier unexpectedly has a better effect, and a good separation effect of magnesium hydroxide and water in the colloid can be obtained under the premise of lower dosage.

In the present invention, the different types of modifiers can be used alone or in combination. The study found that under the modifier, the further control of the dosage is helpful to further exert the synergistic effect between the modifier, the magnesium hydroxide particles and the gas, which is helpful to further improve the Dehydration rate of magnesium hydroxide colloid.

Preferably, based on the weight of the magnesium hydroxide colloidal solution, the amount of the carboxylic acid modifier is not less than (not less than or equal to in the present invention) 30g/t, preferably 30~ 200 g/t; more preferably 30~100 g/t.

Preferably, based on the weight of the magnesium hydroxide colloidal solution, the amount of the amine modifier is preferably not less than 5g/t, preferably 5~50g/t; more preferably 5~30g /t; more preferably 10 to 20 g/t.

Preferably, based on the weight of the magnesium hydroxide colloidal solution, the consumption of the sulfonic acid modifier or the sulfuric acid modifier is not less than 50 g/t, preferably 50 to 350 g/t; Preferably 200~300 g/t.

The present invention also finds that the use of the compound modifier can further improve the dehydration rate of magnesium hydroxide colloid, the recovery rate, purity and colloid dehydration rate of magnesium hydroxide based on the synergistic effect between the modifiers.

Preferably, the modifier includes an amine modifier, and optionally includes at least one of a sulfonic acid modifier, a sulfuric acid modifier, and a carboxylic acid modifier.

In step (1) of the present invention, an existing method can be used to mix the modifier and the colloidal solution, such as mechanical stirring.

The mixing time is not particularly required, and in consideration of processing effect and process efficiency, the mixing time is preferably 3 to 5 min.

In the present invention, the foaming agent is at least one of terpineol oil, industrial No. 2 oil and MIBC. Based on the weight of the magnesium hydroxide colloidal solution, the consumption of the foaming agent is 5-10 g/t.

In the present invention, gas is blown into the mixed system, and based on the gas-solid-liquid three-phase interaction of the modifier, magnesium hydroxide particles and bubbles, the inhibition and decomposition of magnesium hydroxide hydrate can be effectively achieved, Forming hydrophobic aggregates and avoiding further hydration into colloids can effectively achieve separation of magnesium hydroxide and water in colloids.

In the present invention, the type of gas to be charged is not required, for example, air, nitrogen, inert gas, etc. are all acceptable, preferably air.

In step (2), the time of filling gas is not less than 0.5min; preferably 3min and above; further preferably 3~10min. The technical scheme of the present invention, based on the effect of the modifier on magnesium hydroxide hydrate, can inhibit hydration and avoid desorption, and in combination with the joint control of the aeration time, it is not necessary to adjust the aeration process during the aeration process. The solids on the surface are continuously recovered, and a good separation effect of magnesium hydroxide and water can be obtained after only one gassing and one standing.

In step (3), the standing time is not less than 5min, preferably 5-120min. By standing for stratification, the dehydration rate of the magnesium hydroxide colloidal solution is over 75%, and the moisture content of the upper layer of magnesium hydroxide is about 80-90%.

In the present invention, the existing means can be used to separate the upper layer after standing for stratification to obtain the upper layer of magnesium hydroxide.

The present invention also provides a medicament for dehydrating magnesium hydroxide colloidal solution to recover magnesium hydroxide, comprising the modifier described in any one of formula 1 to formula 4.

Preferably, the medicament comprises an amine modifier of formula 1.

More preferably, it contains the amine modifier of formula 1, and also contains at least one of the sulfonic acid modifiers of formula 2, the sulfuric acid modifier of formula 3, and the carboxylic acid modifier of formula 4. A sort of.

More preferably, the weight part of the amine modifier is 10-30 parts; the weight part of other modifiers is 0-300 parts.

More preferably, the medicament comprises an amine modifier and a carboxylic acid modifier, wherein the weight portion of the amine modifier is 10 to 30 parts; the weight portion of the carboxylic acid modifier is 30 to 30 parts by weight. 90 servings.

Alternatively, the medicament includes an amine modifier and a sulfonic acid modifier, wherein the weight portion of the amine modifier is 10-30 parts; the weight portion of the sulfonic acid modifier is 200-300 parts .

Alternatively, the medicament includes an amine modifier, a sulfonic acid modifier, and a carboxylic acid modifier, wherein the weight part of the amine modifier is 10-30 parts; The weight part is 200-300 parts; the weight part of the carboxylic acid modifier is 30-90 parts.

beneficial effect

1. The present invention discovers for the first time that the modifier modifies magnesium hydroxide hydrate, destroys the hydration structure and inhibits the formation of hydration, thereby enabling the selective separation of magnesium hydroxide and water in the colloid.

2. The present invention provides a brand-new idea for separating magnesium hydroxide from magnesium hydroxide colloid, that is, destroying the structure of magnesium hydroxide hydrate and making it hydrophobic to aggregate to the upper layer, and the water phase is located in the lower layer, so as to realize the separation of magnesium hydroxide in the magnesium hydroxide colloid. Selective separation of magnesium hydroxide and water.

3. It is found in the research of the present invention that, thanks to the synergistic effect of the modifier, the magnesium hydroxide particles and the gas-filled three-phase system, the dehydration rate of the magnesium hydroxide colloid can be unexpectedly improved, and the hydrogen Efficient recovery of magnesium hydroxide from magnesium oxide colloids.

The technical scheme of the present invention adopts the foam separation method to realize the high-efficiency solid-liquid separation and recovery of the magnesium hydroxide colloidal solution. By adding an appropriate amount of modifier to the magnesium hydroxide colloidal solution, mixing and aerating, the modifier is used to improve the hydroxide The surface of magnesium precipitation is hydrophobic, and under the action of modifier and air bubbles, magnesium hydroxide is precipitated to form hydrophobic aggregates, which are separated from the water phase to achieve high-efficiency solid-liquid separation and recovery of magnesium hydroxide colloid. Through the foam separation method, the precipitation and recovery of magnesium resources such as salt lake brine and diaphoretic salt can be achieved, and the recovery rate can reach more than 95%. The foam separation method overcomes the traditional direct precipitation method to produce magnesium hydroxide. Problems such as poor sedimentation performance and filtration performance simplify the process, shorten the process time, have no pollution to the environment, and have broad application prospects.

The technical scheme of the present invention utilizes the synergistic effect of the modifier and the air bubbles to strengthen the hydrophobicity of the magnesium hydroxide precipitation, and the modifier, the air bubbles and the magnesium hydroxide precipitation form a hydrophobic aggregate to strengthen the separation of the magnesium hydroxide precipitation and the water phase, thereby realizing High-efficiency solid-liquid separation and recovery of magnesium hydroxide colloid, the purity of magnesium hydroxide obtained by directly drying the foam is more than 95%.

Description of drawings

Fig. 1 is the process flow schematic diagram of the present invention.

FIG. 2 is a picture of the colloid separation of Example 1. FIG.

FIG. 3 is an uninflated picture of Comparative Example 1. FIG.

FIG. 4 is a picture of Comparative Example 2 without adding a modifier.

Figure 5 is a picture of Comparative Example 3 after inflation and standing.

Embodiments of the present invention

The content of the present invention will be further described in detail below with reference to specific embodiments, and the protection scope of the claims of the present invention is not limited by the embodiments.

In the following examples, the colloidal solution is formed by adding sodium hydroxide solution to the solution containing magnesium ions, and the amount of sodium hydroxide added is 1% of the theoretical molar amount required to convert all magnesium ions in the solution containing magnesium ions into magnesium hydroxide. ~1.2x. In the obtained colloidal solution, the particle size is 30-100 nm, and the pH is 9.0-9.4.

In the following cases, unless otherwise stated, the gases described are all air.

In the following cases, unless otherwise stated, the dosage of the medicament is based on the weight of the magnesium hydroxide colloidal solution.

Example 1 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 70g/L, add 300 g/t sodium petroleum sulfonate to the magnesium hydroxide colloidal solution, 15 g/t dodecylamine, 90 g/t sodium oleate, and stirring for 5 min to obtain a magnesium hydroxide mixed solution.

(2) Add 5g/t industrial No. 2 oil to the magnesium hydroxide mixed solution and inflate with gas, and inflate for 5 minutes.

(3) The aerated magnesium hydroxide mixed solution (step (2)) was allowed to stand for 60 min and then layered to obtain an upper layer of magnesium hydroxide and a water layer (lower layer) (as shown in Figure 2). The colloidal dehydration rate of magnesium hydroxide 83%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 98% and a recovery rate of magnesium hydroxide of 98%.

Example 2 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 50g/L, add 200 g/t sodium petroleum sulfonate to the magnesium hydroxide colloidal solution, 20 g/t g/t dodecylamine, stirring and slurrying for 5 min to obtain a magnesium hydroxide mixed solution.

(3) The aerated magnesium hydroxide mixture was left standing for 45 minutes and then layered to obtain the upper layer of magnesium hydroxide and the water layer, and the dehydration rate of magnesium hydroxide colloid was 81%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 99%.

Example 3 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 30 g/L, add 10 g/t dodecylamine to the magnesium hydroxide colloidal solution, 30 g/t g/t sodium oleate was stirred and slurried for 5 minutes to obtain a magnesium hydroxide mixed solution.

(3) The aerated magnesium hydroxide mixture was left standing for 20 min and then layered to obtain an upper layer of magnesium hydroxide and a water layer, and the dehydration rate of magnesium hydroxide colloid was 79%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Example 4 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 15 g/t dodecylamine to the magnesium hydroxide colloidal solution, 200 g/t g/t sodium petroleum sulfonate, stirring and slurrying for 5 min to obtain a magnesium hydroxide mixed solution.

(2) Add 5g/t industrial No. 2 oil to the magnesium hydroxide mixed solution and inflate with gas, and inflate for 2 min.

(3) The aerated magnesium hydroxide mixture was left standing for 60 min and then layered to obtain an upper layer of magnesium hydroxide and a water layer, and the dehydration rate of magnesium hydroxide colloid was 80%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a magnesium hydroxide recovery rate of 97%.

Example 5 .

Compared with Example 4, the main difference is that different dosages of single modifiers are used, specifically.

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 15 g/t dodecylamine to the magnesium hydroxide colloidal solution, and stir and adjust the slurry for 5 minutes to obtain magnesium hydroxide mixture.

(3) The aerated magnesium hydroxide mixture was left standing for 60 min and then layered to obtain the upper layer and the water layer of magnesium hydroxide. The dehydration rate of magnesium hydroxide colloid was 75%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Example 6 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 200 g/t sodium petroleum sulfonate to the magnesium hydroxide colloidal solution, stir and adjust the slurry for 5 minutes to obtain hydroxide Magnesium mixture.

(3) The aerated magnesium hydroxide mixture was left standing for 60 min and then layered to obtain an upper layer of magnesium hydroxide and a water layer, and the dehydration rate of magnesium hydroxide colloid was 73%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Example 7 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 30 g/t sodium oleate to the magnesium hydroxide colloidal solution, stir and adjust the slurry for 5 minutes to obtain magnesium hydroxide mixture.

(3) The aerated magnesium hydroxide mixture was left standing for 60 min and then layered to obtain an upper layer of magnesium hydroxide and a water layer, and the dehydration rate of magnesium hydroxide colloid was 74%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 99%.

Example 8 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 30 g/t dodecylamine to the magnesium hydroxide colloidal solution, stir and adjust the slurry for 10 minutes to obtain magnesium hydroxide mixture.

(3) The aerated magnesium hydroxide mixture was left standing for 50 min and then layered to obtain the upper layer of magnesium hydroxide and the water layer. The dehydration rate of magnesium hydroxide colloid was 76%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Example 9 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 260 g/t sodium petroleum sulfonate to the magnesium hydroxide colloidal solution, stir and adjust the slurry for 5 minutes to obtain hydroxide Magnesium mixture.

(2) Add 5g/t industrial No. 2 oil to the magnesium hydroxide mixed solution and inflate with gas, and inflate for 3 minutes.

(3) The aerated magnesium hydroxide mixture was left standing for 70 minutes and then layered to obtain the upper layer and the water layer of magnesium hydroxide. The dehydration rate of magnesium hydroxide colloid was 75%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 98% and a magnesium hydroxide recovery rate of 99%.

Example 10 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 50 g/t sodium oleate to the magnesium hydroxide colloidal solution, and stir and adjust the slurry for 10 minutes to obtain magnesium hydroxide mixture.

(3) The aerated magnesium hydroxide mixture was left standing for 60 min and then layered to obtain the upper layer and the water layer of magnesium hydroxide. The dehydration rate of magnesium hydroxide colloid was 75%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a magnesium hydroxide recovery rate of 97%.

Example 11 .

Compared with Example 8, the main difference is that two modifiers are used in combination, specifically.

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20g/L, add 15g/t dodecylamine to the magnesium hydroxide colloid solution, 15g/t Sodium oleate, stirring and slurrying for 10 minutes to obtain a magnesium hydroxide mixed solution.

(3) The aerated magnesium hydroxide mixture was left for 50 minutes and then layered to obtain the upper layer and the water layer of magnesium hydroxide. The dehydration rate of magnesium hydroxide colloid was 81%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Compared with Example 8, the combined use of dodecylamine and sodium oleate can unexpectedly produce a synergistic effect, which helps to further improve the dehydration rate of the colloid.

Example 12 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 20 g/L, add 30 g/t dodecylamine to the magnesium hydroxide colloidal solution, 150 g/t g/t sodium petroleum sulfonate, stirring and slurrying for 10 min to obtain a magnesium hydroxide mixed solution.

(3) The aerated magnesium hydroxide mixture was left standing for 50 min and then layered to obtain the upper layer of magnesium hydroxide and the water layer. The dehydration rate of magnesium hydroxide colloid was 79%. The magnesium hydroxide foam is dried to obtain a magnesium hydroxide product with a purity of 99% and a recovery rate of magnesium hydroxide of 98%.

Compared with Examples 6 and 9, a certain amount of dodecylamine is added to the modifier, which can produce a synergistic effect, and can also show a better dehydration rate at a lower total dosage.

Comparative Example 1 .

Compared with Example 1, the only difference is that no gas is introduced (gas-solid-liquid three-phase treatment is not performed), specifically.

(2) Without filling the gas into the mixture, let it stand for 60 min (as shown in Figure 3), the magnesium hydroxide colloid did not delaminate.

Comparative Example 2 .

Compared with Example 1, the only difference is that no modifier is added, specifically.

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 70g/L, without adding any modifier, directly stir and adjust the slurry for 5min to obtain a magnesium hydroxide mixed solution.

(2) Add 5g/t industrial No. 2 oil to the mixed solution, fill it with gas, and let it stand for 360 min directly (as shown in Figure 4). The magnesium hydroxide colloid has a poor stratification effect. The upper layer is recovered, and its dehydration rate is estimated to be only 10%, and it is difficult to recover magnesium hydroxide through processes such as filtration and drying.

Comparative Example 3 .

(1) Select a magnesium hydroxide colloidal solution, the concentration of magnesium hydroxide in the colloidal solution is 70g/L, add 1000 g/t butyl xanthate, stir and adjust the slurry for 5min to obtain a magnesium hydroxide mixed solution.

(3) The aerated magnesium hydroxide mixture was allowed to stand for 50 min (Figure 5). Although the magnesium hydroxide upper layer and water layer could be obtained, the dehydration rate of magnesium hydroxide colloid was only 36%.

It can be seen that the selective separation of magnesium hydroxide and water in the colloid of the present invention cannot be achieved at all by using the existing conventional collection methods.

Claims

A method for separation of magnesium hydroxide colloid solution foam, it is characterized in that, comprises the following steps:

Step 1) Add a modifier to the magnesium hydroxide colloidal solution and mix to obtain a mixed solution; the modifier is an amine modifier of formula 1, a sulfonic acid modifier of formula 2, and a At least one of the sulfuric acid modifiers of the structural formula 3 and the carboxylic acid modifiers of the structural formula 4;

Said R 1 to R 4 are independently C 10 to C 30 saturated hydrocarbon groups or hydrocarbon groups with 1 to 3 unsaturated bonds, or

which is a six-membered ring hydrocarbon group;

The M is H, Na, K or NH 4 + ;

Described A is -OH, -ONa, -OK, -ONH 4 + , -NOH or -OR; Described R is C 1～C 6 alkyl;

Step 2) Add a foaming agent to the mixture and fill it with gas;

Step 3) The aerated mixed solution is allowed to stand and layer to obtain an upper layer of magnesium hydroxide and a water layer.
The method for foam separation of magnesium hydroxide colloidal solution according to claim 1, characterized in that, in the magnesium hydroxide colloidal solution, the particle size of the particles is below 100 nm;

Preferably, the magnesium hydroxide concentration in the magnesium hydroxide colloidal solution is not higher than 80g/L;

Preferably, in step (1), the pH of the magnesium hydroxide colloidal solution is controlled to be 8-11.50.
The method for foam separation of magnesium hydroxide colloidal solution according to claim 1, wherein the amine modifier comprises dodecylamine, tetradecylamine, hexadecylamine, octadecylamine, dodecylamine at least one of them;

Preferably, the sulfonic acid modifier includes at least one of sodium petroleum sulfonate, sodium dodecyl sulfonate, sodium octadecyl sulfonate, and sodium hexadecyl sulfonate;

Preferably, the sulfuric acid modifier is at least one of sodium lauryl sulfate, sodium hexadecyl sulfate, and sodium octadecyl sulfate;

Preferably, the carboxylic acid modifiers include oleic acid, linoleic acid, linolenic acid, lauric acid, myristic acid, capric acid, palmitic acid, stearic acid, naphthenic acid, hydroxamic acid, oxidized paraffin soap , at least one of tall oil, tall oil soap and sodium oleate.
The method for foam separation of magnesium hydroxide colloidal solution according to claim 1, wherein the modifier comprises an amine modifier, and optionally a sulfonic acid modifier and a sulfuric acid modifier , at least one of carboxylic acid modifiers.
The method for foam separation of magnesium hydroxide colloidal solution as claimed in claim 1, is characterized in that, based on the weight of described magnesium hydroxide colloidal solution, the consumption of described carboxylic acid modifier is not less than 30g/ t, preferably 30~200 g/t; more preferably 30~100 g/t;

Preferably, the amount of the amine modifier used is not less than 5 g/t, preferably 5 to 50 g/t; more preferably 5 to 30 g/t; further preferably 10 to 20 g/t;

Preferably, the consumption of the sulfonic acid type modifier or the sulfuric acid type modifier is not less than 50 g/t, preferably 50～350 g/t; preferably 200～300 g/t.
The method for foam separation of magnesium hydroxide colloidal solution as claimed in claim 1, is characterized in that, in step (1), mixing time is 3～5min.
The method for foam separation of magnesium hydroxide colloidal solution as claimed in claim 1, is characterized in that, in step (2), the foaming agent is terpineol oil, No. 2 industrial oil, MIBC at least one; The magnesium oxide colloidal solution is used as the benchmark, and the dosage of the foaming agent is 5-10g/t.
The method for foam separation of magnesium hydroxide colloidal solution as claimed in claim 1, characterized in that, the time for filling gas is not less than 0.5min; preferably 3min and above; further preferably 3～10min.
The method for foam separation of magnesium hydroxide colloidal solution as claimed in claim 1, characterized in that, in step (3), the standing time is not less than 5 min, preferably 5-120 min.
A kind of medicament for magnesium hydroxide colloidal solution dehydration recovery magnesium hydroxide, it is characterized in that, comprise at least one in the modifier described in any one of claim 1～9;

Preferably, the amine modifier of formula 1 is included;

More preferably, it contains the amine modifier of formula 1, and also contains at least one of the sulfonic acid modifiers of formula 2, the sulfuric acid modifier of formula 3, and the carboxylic acid modifier of formula 4. A sort of;

Further preferably, the weight portion of the amine modifier is 10 to 30 parts; the weight portion of other modifiers is 0 to 300 parts;

More preferably, the medicament comprises an amine modifier and a carboxylic acid modifier, wherein the weight portion of the amine modifier is 10 to 30 parts; the weight portion of the carboxylic acid modifier is 30 to 30 parts by weight. 90 copies;

The medicament comprises an amine modifier and a sulfonic acid modifier, wherein the weight portion of the amine modifier is 10-30 parts; the weight portion of the sulfonic acid modifier is 200-300 parts;

The medicament includes an amine modifier, a sulfonic acid modifier, and a carboxylic acid modifier, wherein the weight portion of the amine modifier is 10 to 30 parts; the weight portion of the sulfonic acid modifier It is 200~300 parts; the weight part of the carboxylic acid modifier is 30~90 parts.