CN110976096A

CN110976096A - Beneficiation method for rare earth ore

Info

Publication number: CN110976096A
Application number: CN201911121378.6A
Authority: CN
Inventors: 戴兵; 刘永; 李向阳; 陈英
Original assignee: University of South China
Current assignee: University of South China
Priority date: 2019-11-15
Filing date: 2019-11-15
Publication date: 2020-04-10
Anticipated expiration: 2039-11-15
Also published as: CN110976096B

Abstract

The invention provides a rare earth ore beneficiation method, which is used for sorting micro-fine rare earth ore with the particle size fraction of-30 microns +10 microns by a flotation method. Firstly, preparing an aqueous solution containing 300-600 g/t of a first collecting agent, and mixing slurry of the fine-particle rare earth ore with the aqueous solution; then sequentially adding a pH regulator, an inhibitor and 500-800 g/t of a second collecting agent, and uniformly stirring; and finally, carrying out flotation to obtain concentrate and tailings. The invention selects the aqueous solution containing a certain amount of the first collecting agent for size mixing, and can preliminarily and selectively adsorb useful minerals during size mixing; after size mixing, the self-made trimethylsilylhydroxamic acid is selected as the second collecting agent, the selectivity to rare earth metal is good, the preparation method is simple, the recovery rate of the concentrate obtained by final flotation is up to more than 90%, and the grade is up to more than 65%.

Description

Beneficiation method for rare earth ore

Technical Field

The invention belongs to the technical field of mineral separation, and particularly relates to a mineral separation method for rare earth ores.

Background

Rare earth ores can be classified into mineral type and ionic type according to ore deposits. The mineral type rare earth ore in China is rich in resources, and is typically Baiyunebo iron rare earth niobium ore, Sichuan crown rare earth ore and Shandong Weishan rare earth ore, but the rare earth ore has more complex composition, the embedded particle size of the rare earth ore is fine, and the rare earth ore commonly coexists with gangue minerals such as quartz, fluorite, feldspar, barite, calcite and silicate, so that the rare earth ore needs to be sorted to have use value. The rare earth minerals in the rare earth deposit are generally in compact symbiosis with associated minerals, the embedding particle size is fine, the ores need to be finely ground to enable the rare earth mineral monomers to be dissociated, and the grinding fineness is generally 80-90% of-200 meshes. Since non-sulfide minerals such as rare earth minerals, associated minerals such as fluorite and calcite are brittle and easy to be crushed and argillized during grinding, the classification of the ground minerals is strictly controlled during fine grinding to prevent argillization or desliming is performed before flotation to eliminate adverse effects of the slime during flotation.

The micro-fine particle ore particles have the characteristics of large specific surface area and high surface energy, are suspended in the ore pulp uniformly, have low momentum and small inertia in the process of carrying flow of the ore pulp, are slightly influenced by a magnetic field and a gravity field, cannot achieve ideal separation effect when being treated by magnetic separation and gravity separation processes, and are effective processes for recovering the micro-fine particle rare earth ore by adopting flotation or chemical ore separation under the current ore separation technical conditions. The leaching and roasting-leaching in the chemical beneficiation process can obtain better process indexes, but the disadvantages of high consumption and high pollution of the chemical beneficiation cause the chemical beneficiation to lose the economy.

The flotation method has the problems that the rare earth minerals with fine particle distribution cannot be effectively recovered in the aspect of flotation reagents, so that a large amount of rare earth resources are wasted. For example, the recovery rate of the rare earth minerals in the bayan obo ore area with the largest rare earth reserves in China is less than 20 percent, while the recovery rate of the rare earth minerals in other areas such as the rare earth minerals in the mountainous Weishan mountain and the Sichuan Baoning rare earth minerals is only about 50 percent although the granularity of the rare earth minerals is thicker. In addition, the H205 collector which is widely used at present has the disadvantages of high production cost, little toxicity, large usage amount and easy environmental pollution. The inhibitor for rare earth ore dressing has poor inhibition selectivity on gangue in micro-fine particle rare earth minerals, so that high-grade rare earth concentrate such as Hubei bamboo mountain rare earth ore is difficult to obtain, the ore components are complex, and the inhibitor is not developed and utilized to date because of no proper process.

Hydroximic acid is a collecting agent with strong selectivity, can be used for flotation of various oxidized ores, and the development and utilization of rare earth ores are limited to a certain extent mainly due to the defects of poor selectivity and collecting property, high reagent cost, high reagent toxicity and the like of the hydroximic acid in the field of mineral flotation at present. Therefore, the development of a novel hydroximic acid collecting agent which is low in price, wide in source, strong in collecting capacity and good in selectivity has important theoretical and practical significance for future mineral flotation.

In conclusion, the search for a novel flotation collector with strong collecting capacity, good selectivity, no toxicity and no harm is an urgent problem to be solved.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a rare earth ore dressing method, which is used for sorting micro-fine rare earth ore with the particle size fraction of-30 microns +10 microns by a flotation method, firstly, an aqueous solution containing a certain amount of first collecting agent is prepared, the micro-fine rare earth ore is subjected to size mixing by the aqueous solution, then, a pH regulator, an inhibitor and a second collecting agent are sequentially added, and finally, flotation is carried out to obtain concentrate and tailings, wherein the recovery rate is up to more than 90%, and the grade is up to more than 65%.

In order to achieve the purpose, the invention adopts the following technical scheme:

a rare earth ore beneficiation method comprises the following steps:

s1, desliming: desliming the superfine rare earth ore to remove slime with the particle size of-10 mu m to obtain the superfine rare earth ore with the particle size of-30 mu m +10 mu m;

s2, size mixing: adding 300-600 g/t of a first collecting agent into water, then mixing the micro-fine rare earth ore with the particle size fraction of-30 microns +10 microns in the step S1 until the concentration is 45% -55%, adding a PH regulator, and uniformly stirring to obtain a first mixture; adding an inhibitor into the first mixture, and uniformly stirring to obtain a second mixture; adding 500-800 g/t of a second collecting agent into the second mixture, and uniformly stirring to obtain a third mixture;

s3, flotation: and (5) performing flotation on the third mixture obtained in the step S2 to obtain flotation concentrate and flotation tailings.

Further, the sum of the addition amounts of the first collecting agent and the second collecting agent is more than or equal to 1000 g/t.

Further, the first collecting agent is a composition of a hydroximic acid collecting agent and a surfactant in a mass ratio of 90: 10-98: 2.

Further, the hydroximic acid collecting agent is one of octyl hydroximic acid, benzohydroxamic acid and naphthalimic acid, and the surfactant is sodium dodecyl benzene sulfonate.

Further, the second collector is trimethylsilylhydroxamic acid.

Further, the preparation method of the trimethyl silylethyl hydroximic acid comprises the following steps:

s201, adding a dichloromethane-methanol mixed solvent with a volume ratio of 30: 70-50: 50 into a reactor, then sequentially adding hydroxylamine hydrochloride and sodium hydroxide, and filtering after complete reaction to obtain a filtrate;

s202, adding methyl trimethylsilylacetate into the filtrate obtained in the step S201, reacting at a constant temperature of 35-55 ℃ for 3-5 hours, and then carrying out reduced pressure distillation to obtain a crude product of trimethylsilylethyl hydroximic acid;

s203, repeatedly washing and filtering the crude trimethylsilylethyl hydroximic acid product obtained in the step S202 by using ethanol and ethyl acetate to obtain high-purity trimethylsilylethyl hydroximic acid.

Further, the molar ratio of the hydroxylamine hydrochloride to the sodium hydroxide is 1: (1.05-1.2), wherein the molar ratio of the methyl trimethylsilylacetate to the hydroxylamine hydrochloride is 1: (1.05-1.2).

Further, the pH regulator is sodium hydroxide or sodium carbonate, and the pH value of the first mixture is controlled to be 8.5-9.5.

Further, the inhibitor is one or more of sodium lignosulphonate, hydroxyethyl cellulose or guar gum, and the adding amount of the inhibitor is 600-800 g/t.

Further, the temperature of flotation is 35-45 ℃.

Advantageous effects

Compared with the prior art, the rare earth ore beneficiation method provided by the invention has the following beneficial effects:

(1) according to the invention, the self-made trimethylsilyl ethyl hydroximic acid is used as a second collecting agent, and the result of the flotation of the rare earth ore shows that the organosilicon hydroximic acid has stronger selectivity and collecting property on useful minerals, the recovery rate of concentrate is up to more than 90%, and the grade is up to more than 65%. Three methyl groups in the trimethylsilylethyl hydroximic acid molecules endow the trimethylsilylethyl hydroximic acid molecules with lower surface energy and better hydrophobicity, and after complexing with rare earth metals, the hydrophobicity degree of the mineral surface can be obviously improved, so that the mineral surface is easy to adhere to bubbles, the floatability of the mineral is improved, and the flotation recovery rate is further improved.

(2) The invention takes methyl trimethylsilylacetate and hydroxylamine hydrochloride as main raw materials, and selects dichloromethane and methanol as mixed solvent, thus improving the compatibility of the methyl trimethylsilylacetate. Reacting at the constant temperature of 35-55 ℃ for 3-5 h, and repeatedly washing and filtering with ethanol and ethyl acetate to obtain trimethylsilyl ethyl hydroximic acid, wherein the preparation method has the advantages of simplicity, mild reaction conditions and low toxicity, and the prepared trimethylsilyl ethyl hydroximic acid has good low-temperature resistance and can realize efficient flotation of rare earth ore at the temperature of 35-45 ℃.

(3) According to the invention, before size mixing, an aqueous solution containing a certain amount of first collecting agent is prepared, wherein the first collecting agent consists of hydroximic acid collecting agent and surfactant with the mass ratio of 90: 10-98: 2, compared with the prior art that size mixing is directly carried out by water, selective adsorption can be carried out on useful minerals preliminarily during size mixing, gangue minerals and useful minerals are wetted equally when size mixing is carried out by water directly, and selective adsorption capacity and efficiency on the useful minerals are affected when the collecting agent is added subsequently.

(4) According to the invention, the first collecting agent and the second collecting agent are sequentially added by adopting a two-step method, and the total adding amount of the collecting agent is as low as 1000g/t, so that the recovery rate and grade are high, and compared with the prior art, the use amount of the collecting agent can be obviously reduced, thus the flotation cost of rare earth ore is obviously reduced, and the generation of harmful substances is reduced.

Drawings

Fig. 1 is a schematic flow chart of a rare earth ore beneficiation method provided by the invention.

Detailed Description

The technical solutions of the embodiments of the present invention will be described clearly and completely below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments; all other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without any inventive step, are within the scope of the present invention.

Referring to fig. 1, the method for concentrating rare earth ore according to the present invention includes the following steps:

the sum of the addition amount of the first collecting agent and the second collecting agent is more than or equal to 1000g/t, the first collecting agent is a composition of hydroximic acid collecting agent and surfactant with the mass ratio of 90: 10-98: 2, the second collecting agent is trimethylsilylhydroximic acid, and the synthetic route is shown as the following formula:

By the method, the recovery rate of the concentrate obtained by flotation is up to more than 90%, the grade is up to more than 65%, the flotation cost is obviously reduced, and the generation amount of harmful substances is also obviously reduced. Three methyl groups in the trimethyl silylethyl hydroximic acid molecule prepared by the method are endowed with lower surface energy and better hydrophobicity, and after the trimethyl silylethyl hydroximic acid molecule is complexed with rare earth metal, the hydrophobicity degree of the surface of the mineral can be obviously improved, so that the mineral can be easily adhered to bubbles, the floatability of the mineral is improved, and the flotation recovery rate is further improved.

Example 1

Embodiment 1 provides a method for beneficiation of rare earth ore, which selects rare earth ore from mountainous-east micro mountain as an ore sample for flotation, and includes the following steps:

s1, desliming: desliming the micro-fine rare earth ore in Shandong, removing-10 mu m slime to obtain the micro-fine rare earth ore with the grain size of-30 mu m +10 mu m;

s2, size mixing: adding 450g/t of a first collecting agent into water, then, pulping the micro-fine rare earth ore with the particle size fraction of-30 microns +10 microns in the step S1 until the concentration is 50%, adding sodium hydroxide to control the pH value of the pulp within 8.5-9.5, and uniformly stirring to obtain a first mixture; adding 700g/t of hydroxyethyl cellulose into the first mixture, and uniformly stirring to obtain a second mixture; adding 650g/t of second collecting agent trimethylsilylhydroxamic acid into the second mixture, and uniformly stirring to obtain a third mixture;

the first collecting agent is benzohydroxamic acid and sodium dodecyl benzene sulfonate with the mass ratio of 95: 5; the trimethyl silylethyl hydroximic acid is prepared by the following method:

s201, adding 250ml of dichloromethane-methanol mixed solvent with a volume ratio of 40:60 into a 500ml three-neck flask, and then sequentially adding a solvent with a molar ratio of 1: 1.1, stirring hydroxylamine hydrochloride and sodium hydroxide for reaction at 40 ℃, and filtering to obtain filtrate after complete reaction;

s202, adding methyl trimethylsilanoate into the filtrate obtained in the step S201, wherein the molar ratio of the methyl trimethylsilanoate to the hydroxylamine hydrochloride is 1: 1.1, reacting for 4 hours at a constant temperature of 45 ℃, and then distilling under reduced pressure to obtain a crude product of trimethylsilylhydroxamic acid;

S3, flotation: and (4) carrying out flotation on the third mixture obtained in the step S2 at the temperature of 40 ℃ to obtain flotation concentrate and flotation tailings.

Tests prove that the yield of the high-purity trimethylsilylethyl hydroximic acid is 89%, the recovery rate of the rare earth ore is 91.9%, and the grade is 71%. Compared with the prior art, the recovery rate and the grade are both obviously improved, and the flotation condition is mild.

Examples 2 to 8

The rare earth ore dressing methods provided in embodiments 2 to 8 are different from those in embodiment 1 in that the addition amounts of the first collector, the inhibitor, and the second collector are shown in table 1, and the others are substantially the same as those in embodiment 1, and are not described again here.

Comparative examples 1 to 6

The beneficiation method for rare earth ore provided in comparative examples 1 to 6 is different from that in example 1 in that the addition amounts of the first collecting agent and the second collecting agent are shown in table 1, and the others are basically the same as those in example 1, and are not described again.

TABLE 1 test results of preparation conditions, recovery rates and grades of examples 2 to 8 and comparative examples 1 to 6

Test specimen	First collector (g/t)	Second collector (g/t)	Inhibitors (g/t)	Recovery (%)	Grade (%)
						Example 2	300	750	700	91.6	70.9
Example 3	600	600	700	91.4	70.3
						Example 4	600	500	700	90.5	69.7
Example 5	450	600	700	91.2	70.2
						Example 6	450	800	700	91.8	70.8
Example 7	450	650	600	91.3	70.3
						Example 8	450	650	800	91.5	70.5
Comparative example 1	300	650	700	88.5	68.4
						Comparative example 2	250	650	700	85.6	65.3
Comparative example 3	650	650	700	86.8	66.5
						Comparative example 4	450	500	700	86.5	66.3
Comparative example 5	450	450	700	85.4	65.6
						Comparative example 6	450	850	700	88.3	68.0

As can be seen from table 1, the rare earth ore recovery rate and grade did not change much as the addition amount of the first collector increased. Along with the increase of the addition amount of the second collecting agent, the change of the rare earth ore recovery rate and the grade is small after the rare earth ore recovery rate and the grade are gradually increased, the influence of the addition amount of the second collecting agent on the flotation effect of the rare earth ore is larger, the addition amount of the second collecting agent is properly increased, and the improvement of the recovery rate and the grade of the rare earth ore is facilitated. Within the limit range of the invention, the addition amount of the inhibitor has little influence on the recovery rate and the grade of the rare earth ore. From the comparative example, it can be seen that when the sum of the addition amounts of the first collector and the second collector is less than 1000g/t, the recovery rate and grade of the rare earth ore are obviously reduced, and especially when the sum of the addition amounts of the first collector and the second collector is less than 1000g/t, and the addition amount of the first collector or the second collector is less than the minimum value of the defined range, the recovery rate and grade of the rare earth ore are most obviously reduced. The adding amount of the collecting agent is too low, so that the useful minerals cannot be effectively selected and collected.

Examples 9 to 14

The rare earth ore beneficiation methods provided in examples 9 to 14 are different from those in example 1 in that the volume ratio of dichloromethane to methanol, the molar ratio of hydroxylamine hydrochloride to sodium hydroxide, and the molar ratio of methyl trimethylsilylacetate to hydroxylamine hydrochloride are shown in table 2, and the others are substantially the same as those in example 1 and are not repeated herein.

Table 2 test results of preparation conditions, yield, recovery rate and grade of examples 9 to 14

As can be seen from Table 2, with the increase of the volume ratio of dichloromethane to methanol, the yield of trimethylsilylhydroxamic acid is gradually reduced, and the recovery rate and grade of rare earth ore are correspondingly reduced, which indicates that the methanol content is too low to facilitate the reaction. Within the limit range of the invention, the molar ratio of the hydroxylamine hydrochloride and the sodium hydroxide and the molar ratio of the methyl trimethylsilylacetate and the hydroxylamine hydrochloride have little influence on the yield, and the recovery rate and the grade are not changed greatly.

Comparative example 7

The method for concentrating rare earth ore according to comparative example 7 is different from that of example 1 in that step S2 is as follows:

size mixing: using pure water to size the micro-fine rare earth ore with the particle size fraction of-30 microns +10 microns in the step S1 to 50%, adding sodium hydroxide to control the pH of the ore pulp within 8.5-9.5, and uniformly stirring to obtain a first mixture; adding 700g/t of hydroxyethyl cellulose into the first mixture, and uniformly stirring to obtain a second mixture; adding 450g/t of first collecting agent and 650g/t of second collecting agent trimethyl silyl hydroximic acid into the second mixture, and uniformly stirring to obtain a third mixture;

other preparation methods and steps are basically the same as those of embodiment 1, and are not repeated herein.

The test shows that the recovery rate of the rare earth ore in the comparative example 7 is 88.9 percent, and the grade is 68.2 percent. Compared with the example 1, the method is obviously reduced, and the aqueous solution containing a certain amount of the first collecting agent is selected for size mixing, so that the flotation recovery rate and the grade are improved. The reason is that the aqueous solution containing a certain amount of the first collecting agent is selected for size mixing, so that the useful minerals can be initially and selectively adsorbed during size mixing, when water is directly used for size mixing, gangue minerals and the useful minerals are equally wetted, and when the collecting agent is subsequently added, the selective adsorption capacity and the efficiency of the useful minerals are affected.

Comparative example 8

The ore dressing method for rare earth ore provided in comparative example 8 is different from that of example 1 in that the second collector is benzohydroxamic acid in step S2, and the rest is basically the same as that of example 1, and is not described again.

The test shows that the recovery rate of the rare earth ore in the comparative example 8 is 86.8 percent, and the grade is 66.2 percent. The obvious reduction is compared with example 1, which shows that the trimethyl silyl hydroximic acid prepared by the invention has more excellent selectivity and collecting property compared with benzohydroxamic acid. The reason is that three methyl groups in the trimethylsilylethyl hydroximic acid molecules endow the trimethylsilylethyl hydroximic acid molecules with lower surface energy and better hydrophobicity, and after the trimethylsilylethyl hydroximic acid molecules are complexed with rare earth metals, the hydrophobicity of the mineral surface can be obviously improved, so that the mineral surface can be easily adhered to bubbles, the floatability of the mineral is improved, and the flotation recovery rate is further improved.

Comparative example 9

The rare earth ore dressing method provided in comparative example 9 is different from that of example 1 in that the second collector is not added in step S2, and the rest is substantially the same as that of example 1, and thus, the description thereof is omitted.

The test result shows that the recovery rate of the rare earth ore of the comparative example 9 is only 76.6%, and the grade is only 57.2%. Compared with the embodiment 1 and the comparative example 8, the method has the advantages that the method is obviously reduced, the necessity of adding the second collecting agent is illustrated, and the second collecting agent is trimethyl silyl ethyl hydroximic acid prepared by the method, so that the recovery rate and the grade are better.

In conclusion, the invention selects the aqueous solution containing a certain amount of first collecting agent for size mixing and selects the self-made trimethylsilylhydroximic acid as the second collecting agent, thereby realizing high selectivity and high collecting property on the rare earth ore, and the recovery rate of the concentrate obtained by final flotation is up to more than 90 percent and the grade is up to more than 65 percent.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims

1. The rare earth ore beneficiation method is characterized by comprising the following steps:

2. The rare earth ore dressing method according to claim 1, wherein the sum of the addition amounts of the first collecting agent and the second collecting agent is not less than 1000 g/t.

3. The rare earth ore dressing method according to claim 1, wherein the first collector is a composition of a hydroximic acid collector and a surfactant in a mass ratio of 90: 10-98: 2.

4. The method for concentrating rare earth ore according to claim 3, wherein the hydroximic acid collecting agent is one of octyl hydroximic acid, benzohydroxamic acid and naphthalimic acid, and the surfactant is sodium dodecyl benzene sulfonate.

5. The method for concentrating rare earth ore according to claim 1, wherein the second collector is trimethylsilylhydroxamic acid.

6. The method for concentrating rare earth ore according to claim 5, wherein the preparation method of trimethylsilylhydroxamic acid comprises the following steps:

7. The method for beneficiating a rare earth ore according to claim 6, wherein the molar ratio of the hydroxylamine hydrochloride to the sodium hydroxide is 1: (1.05-1.2), wherein the molar ratio of the methyl trimethylsilylacetate to the hydroxylamine hydrochloride is 1: (1.05-1.2).

8. The method for concentrating rare earth ore according to claim 1, wherein the PH adjusting agent is sodium hydroxide or sodium carbonate, and the PH of the first mixture is controlled to be 8.5 to 9.5.

9. The rare earth ore dressing method according to claim 1, wherein the inhibitor is one or more of sodium lignosulfonate, hydroxyethyl cellulose or guar gum, and the addition amount of the inhibitor is 600-800 g/t.

10. The rare earth ore dressing method according to claim 1, wherein the temperature for flotation is 35-45 ℃.