A chemical beneficiation method for low-grade bastnaesite concentrate

Abstract

The present invention provides a chemical beneficiation method for low-grade bastnaesite concentrate, wherein the low-grade bastnaesite concentrate contains at least two minerals, bastnaesite and sodium carbonate cerium ore, and the method comprises: dissolving the low-grade bastnaesite concentrate with dilute acid so that the sodium carbonate cerium ore is dissolved in the dilute acid to obtain a soluble salt solution; wherein the soluble salt solution contains rare earth and calcium strontium barium sodium; recovering rare earth from the soluble salt solution and secondary rare earth concentrate; wherein the rare earth minerals in the secondary rare earth concentrate are basically composed of the bastnaesite that is not soluble in dilute acid. The present invention processes the concentrate by a chemical beneficiation method to obtain a high-grade secondary rare earth concentrate and a soluble salt solution containing rare earth, and then recovers rare earth from the secondary rare earth concentrate and the soluble salt solution containing rare earth, thereby improving the overall yield, and from the low-grade bastnaesite concentrate to the rare earth chloride solution, the total yield of rare earth beneficiation can be guaranteed to be above 90%.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth beneficiation, and in particular to a chemical beneficiation method for low-grade bastnaesite concentrate. Background Art

[0002] Fluorocarbon cerium is the world's largest rare earth mineral. About 70% of the world's rare earth products come from fluorocarbon cerium. my country's Bayan Obo rare earth mine in Inner Mongolia, Mianning and Dechang rare earth mines in Sichuan, and Weishan rare earth mine in Shandong are all large rare earth deposits dominated by fluorocarbon cerium. In addition to fluorocarbon cerium, the rare earth minerals in the fluorocarbon cerium ore also contain monazite, sodium carbonate cerium ore, and strontium calcium cerium ore. Its gangue is mainly composed of calcite, magnesite, strontium ore, amphibole, and barite.

[0003] In order to recover the rare earths in the fluorocarbon cerium ore, Shandong Weishan Rare Earth Mine first uses the physical beneficiation process of "one roughing, two sweeping and three fines" to obtain a fluorocarbon cerium ore concentrate with a rare earth grade of 40% REO (the rare earth content in the rare earth material is calculated as rare earth oxide REO, the same below), and then treats the fluorocarbon cerium ore concentrate by sulfuric acid roasting. In addition, with the change of resource endowment, there are more and more sodium carbonate cerium ores in the raw ore, which has a greater impact on rare earth recovery.

[0004] Therefore, the following technical problems exist in the field of low-grade bastnaesite concentrate beneficiation technology: (1) It is difficult to effectively separate sodium carbonate cerium ore from bastnaesite in bastnaesite ore by traditional physical beneficiation such as flotation, gravity separation or magnetic separation. As a result, sodium carbonate cerium ore will be carried into the bastnaesite concentrate after beneficiation, resulting in low beneficiation yield and reduced grade; (2) The sodium element in sodium carbonate cerium ore will also interfere with the sulfuric acid roasting treatment of bastnaesite concentrate. The sodium element causes rare earth to be lost in the acid leaching slag and neutralization slag in the form of sulfate rare earth complex salts, resulting in low yield of rare earth during smelting and separation. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a chemical beneficiation method for low-grade bastnaesite concentrate, wherein the low-grade bastnaesite concentrate contains at least two minerals, bastnaesite and sodium carbonate cerium ore, and the method comprises:

[0006] Dissolving low-grade bastnaesite concentrate with dilute acid, so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain a soluble salt solution; wherein the soluble salt solution contains rare earth and calcium, strontium, barium and sodium;

[0007] Recovering rare earths from the soluble salt solution and the secondary rare earth concentrate; wherein the rare earth minerals in the secondary rare earth concentrate are substantially composed of the fluorocarbon cerium ore which is insoluble in dilute acid.

[0008] Preferably, the dilute acid is at least one of hydrochloric acid, acetic acid or nitric acid.

[0009] Preferably, the concentration of the dilute acid is 0.5-4.0 mol / L.

[0010] Preferably, the low-grade bastnaesite concentrate is dissolved with dilute acid so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain a soluble salt solution, comprising:

[0011] When the low-grade bastnaesite concentrate is dissolved by using dilute acid, the temperature is controlled at 15-40° C. so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain the soluble salt solution.

[0012] Preferably, the rare earth grade in the low-grade bastnaesite concentrate is 15% to 40% REO; the rare earth in the sodium carbonate cerium ore accounts for 10% to 80% of the total rare earth in the low-grade bastnaesite concentrate; the rare earth grade in the secondary rare earth concentrate is 40% to 70% REO.

[0013] Preferably, the pH value of the soluble salt solution is 3.0-4.0.

[0014] Preferably, recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises:

[0015] washing the secondary rare earth concentrate to remove chloride ions in the secondary rare earth concentrate;

[0016] After washing, sulfuric acid is added to the secondary rare earth concentrate and subjected to a sulfate roasting process to recover the rare earths; wherein the sulfate roasting process includes roasting, water leaching, neutralization and impurity removal, and transformation.

[0017] Preferably, the chloride ion content in the secondary rare earth concentrate after washing is less than 0.5%.

[0018] Preferably, in the process of adding sulfuric acid to the washed secondary rare earth concentrate for sulfation roasting, the mass ratio of the sulfuric acid to the washed secondary rare earth concentrate is 0.9-2.0, the roasting temperature is 150-400° C., and the water immersion temperature is 15-50° C.;

[0019] The neutralization and impurity removal is to use at least one of magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide or magnesium bicarbonate to remove impurities to obtain a rare earth sulfate solution with a pH value of 3.0 to 4.0; wherein the rare earth content in the rare earth sulfate solution is 17 to 45 gREO / L;

[0020] The transformation is to transform the rare earth sulfate solution by rare earth carbonate precipitation or extraction to obtain a rare earth chloride solution.

[0021] Preferably, recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises:

[0022] The soluble salt solution is precipitated using at least one of sodium carbonate, sodium bicarbonate or ammonium bicarbonate, or the soluble salt solution is extracted using an acidic extractant to recover the rare earth in the soluble salt solution.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] The present invention provides a chemical beneficiation method for low-grade bastnaesite concentrate, wherein the low-grade bastnaesite concentrate contains at least two minerals, bastnaesite and sodium carbonate cerium ore, and the method comprises: dissolving the low-grade bastnaesite concentrate with dilute acid so that the sodium carbonate cerium ore is dissolved in the dilute acid to obtain a soluble salt solution; wherein the soluble salt solution contains rare earth and calcium strontium barium sodium; recovering rare earth from the soluble salt solution and secondary rare earth concentrate; wherein the rare earth minerals in the secondary rare earth concentrate are basically composed of the bastnaesite that is not soluble in dilute acid. The present invention processes the concentrate by a chemical beneficiation method to obtain a high-grade secondary rare earth concentrate and a soluble salt solution containing rare earth, and then recovers rare earth from the secondary rare earth concentrate and the soluble salt solution containing rare earth, thereby improving the overall yield, and ensuring that the total yield of rare earth beneficiation is above 90% from the low-grade bastnaesite concentrate to the end of recovery.

[0025] The present invention performs chemical ore dressing on low-grade fluorocarbon cerium ore concentrate, dissolves sodium cerium carbonate ore therein with dilute acid, obtains a soluble salt solution containing rare earth and calcium, strontium, barium and sodium, and the fluorocarbon cerium ore is basically insoluble in dilute acid, thereby achieving the purpose of selectively removing sodium cerium carbonate ore from the low-grade fluorocarbon cerium ore concentrate, ensuring the rare earth yield and the grade of the fluorocarbon cerium ore; removing the sodium cerium carbonate ore containing sodium, ensuring that the rare earth yield will not be further reduced due to the presence of sodium element during the sulfuric acid roasting process (the precipitation of rare earth sulfate complex salt produced by the sodium element will affect the rare earth yield), and solving the problem of reduced rare earth yield during the sulfuric acid roasting process. By adopting the present invention, the fluorocarbon cerium ore is dissolved by dilute acid, which can effectively improve the rare earth yield during the sulfuric acid roasting process, and the rare earth yield of the fluorocarbon cerium ore is maintained at more than 90%; the rare earth in the sodium cerium carbonate ore is dissolved by dilute acid, and recovered by precipitation or extraction method. Ultimately, it can be ensured that the total yield of rare earth beneficiation is greater than 90% from the low-grade bastnaesite concentrate as the raw material to the end of recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 The present invention is a flowchart of the steps of a chemical beneficiation method for low-grade bastnaesite concentrate according to an embodiment of the present invention. DETAILED DESCRIPTION

[0027] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific examples, but should not be construed as limiting the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. Unless otherwise specified, the examples, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0028] Sodium cerium carbonate was first discovered in the Kola Peninsula, and was later found in the Bayan Obo iron-rare earth-niobium mine in my country and the Weishan Lake rare earth mine in Shandong. In particular, the mineral showed a significant increase during the deep development of the Weishan Lake rare earth mine in Shandong. Sodium cerium carbonate is an orthorhombic system containing rare earth, strontium, calcium, sodium and barium elements. Its composition is complex. When it coexists with fluorocarbon cerium in the original ore, it interferes with the traditional physical beneficiation process, reduces the concentrate grade and beneficiation yield, and also reduces the rare earth yield in the subsequent concentrate sulfuric acid roasting process.

[0029] According to theoretical calculations, the rare earth content of pure bastnaesite is 74.77% REO, and the rare earth content of pure sodium carbonate cerium ore is about 33% REO. This means that when the proportion of sodium carbonate cerium in the bastnaesite ore is large enough, even if the rare earth minerals are completely selected by flotation, it is impossible to obtain a bastnaesite concentrate with a REO content of >40% in the traditional sense.

[0030] Fluorocarbon cerium ore concentrate with a grade of 40% REO and below is not suitable for oxidation roasting-hydrochloric acid leaching or alkaline treatment. It is generally treated by sulfuric acid roasting, and the rare earth yield can reach more than 90%. However, research and industrial practice have found that as sodium cerium carbonate minerals enter the fluorocarbon cerium ore concentrate, when the rare earth content in the form of sodium cerium carbonate minerals is greater than 10%, the rare earth yield of the fluorocarbon cerium ore concentrate treated by sulfuric acid roasting is less than 85%, and as the proportion of sodium cerium carbonate minerals in the concentrate increases, the rare earth yield of the concentrate treated by sulfuric acid roasting will show a significant decline.

[0031] In view of this, the present invention provides a chemical beneficiation method for low-grade bastnaesite concentrate, wherein the low-grade bastnaesite concentrate contains at least two minerals, bastnaesite and sodium carbonate cerium ore. Figure 1 As shown, a flow chart of the steps of a chemical beneficiation method for low-grade bastnaesite concentrate according to an embodiment of the present invention is shown, and the method comprises:

[0032] S1, using dilute acid to dissolve low-grade fluorocarbon cerium ore concentrate, so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain a soluble salt solution; wherein the soluble salt solution contains rare earth and calcium, strontium, barium and sodium;

[0033] S2, recovering rare earths from the soluble salt solution and the secondary rare earth concentrate; wherein the rare earth minerals in the secondary rare earth concentrate are substantially composed of the fluorocarbon cerium ore which is insoluble in dilute acid.

[0034] Among them, the rare earth minerals in the secondary rare earth concentrate include not only fluorocarbon cerium ore which is insoluble in dilute acid, but also a small amount of sodium cerium carbonate mineral which is insoluble in dilute acid.

[0035] In the embodiment of the present invention, rare earths in two kinds of rare earth minerals are recovered respectively: on the one hand, the rare earth yield in the secondary rare earth concentrate sulphate roasting method can be improved to more than 90%; on the other hand, the rare earth in sodium carbonate cerium ore dissolved in dilute acid is recovered, and the rare earth yield is greater than 90%. Finally, it can be ensured that the total yield of rare earth beneficiation and smelting from low-grade fluorocarbon cerium ore concentrate as raw material to the recovery of rare earth chloride solution is greater than 90%.

[0036] By chemically dressing low-grade bastnaesite concentrate, dissolving sodium cerium carbonate in it with dilute acid, a soluble salt solution containing rare earth and calcium, strontium, barium and sodium is obtained, as well as a secondary rare earth concentrate containing bastnaesite that is basically insoluble in dilute acid, wherein the rare earth grade is greatly improved, thereby ensuring the yield and grade of bastnaesite; dissolving sodium cerium carbonate from bastnaesite ensures that the secondary rare earth concentrate will not produce rare earth sulfate complex salt precipitation due to the presence of sodium during the sulfuric acid roasting process, thereby ensuring a high yield of rare earth. The washed secondary rare earth concentrate is subjected to sulfuric acid roasting, water leaching, neutralization and impurity removal, and transformation to obtain a rare earth chloride solution, whose rare earth yield is above 90%.

[0037] In addition, by adopting chemical beneficiation for low-grade rare earth concentrate, various carbonate minerals such as calcite, magnesite, strontianite, etc. associated with low-grade fluorocarbon cerium ore concentrate can also be separated at the same time. That is, dilute acid selectively dissolves calcite, magnesite, strontianite, etc. from low-grade fluorocarbon cerium ore concentrate, thereby improving the grade of secondary rare earth concentrate, reducing the influence of impurities on the subsequent sulfuric acid roasting of secondary concentrate, reducing the consumption of chemical raw materials and improving the rare earth yield.

[0038] It should be noted that most of the rare earths in the low-grade fluorocarbon cerium ore concentrate come from sodium carbonate cerium ore and fluorocarbon cerium ore, but in addition to this, the low-grade fluorocarbon cerium ore concentrate also contains other small amounts of rare earths. The present invention does not impose any restrictions on the method for recovering this small amount of rare earths. The method of the present invention is only aimed at the recovery of rare earths in sodium carbonate cerium ore and fluorocarbon cerium ore.

[0039] Preferably, the dilute acid is at least one of hydrochloric acid, acetic acid or nitric acid.

[0040] In this embodiment, sodium cerium carbonate ore is dissolved in dilute acid to undergo an acid dissolution reaction to obtain a soluble salt solution containing rare earth, sodium, barium, calcium and strontium.

[0041] Preferably, the concentration of the dilute acid is 0.5-4.0 mol / L.

[0042] The concentration of the dilute acid may specifically be 0.5, 0.6, 0.7, ..., 4.0.

[0043] In this embodiment, the concentration of the dilute acid may be further preferably 0.5 to 2.5 mol / L. It is not advisable to use a dilute acid with too high a concentration so as not to affect the recovery of rare earths.

[0044] Preferably, the low-grade bastnaesite concentrate is dissolved with dilute acid so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain a soluble salt solution, comprising:

[0045] When the low-grade bastnaesite concentrate is dissolved by using dilute acid, the temperature is controlled at 15-40° C. so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain the soluble salt solution.

[0046] Among them, the fluoride ion concentration in the soluble salt solution is less than 0.1g / L. In this embodiment, the dissolution temperature may be further preferably 20 to 35°C. It is not advisable to use too high a reaction temperature (above 80°C) to avoid reducing the rare earth yield. For example, the use of a dissolution temperature above 80°C will cause the fluorocarbon cerium ore concentrate to dissolve significantly at high temperatures due to changes in the crystal form, which is mainly reflected in the entry of fluoride ions into the soluble salt solution. When the fluoride ion concentration is greater than 0.1g / L, the next step of recovering rare earths by precipitation or extraction will result in a reduced yield.

[0047] In actual operation, in order to avoid the whole system temperature being too high due to the vigorous dilute acid dissolution reaction, which leads to the dissolution of fluorocarbon cerium ore, the dilute acid dissolution reaction temperature can be controlled by slowing down the feeding speed.

[0048] Preferably, the rare earth grade in the low-grade bastnaesite concentrate is 15% to 40% REO; the rare earth in the sodium carbonate cerium ore accounts for 10% to 80% of the total rare earth in the low-grade bastnaesite concentrate; the rare earth grade in the secondary rare earth concentrate is 40% to 70% REO.

[0049] In this embodiment, the rare earth grade in the low-grade bastnaesite concentrate may preferably be 20% to 35% REO.

[0050] Preferably, the pH value of the soluble salt solution is 3.0-4.0.

[0051] In some embodiments, during the dissolution process using dilute acid, the final acidity of the soluble salt solution containing calcium, strontium, sodium and barium is 3.0-4.0 as the end point of acid addition.

[0052] In order to ensure that the sodium cerium carbonate ore is fully dissolved and the sodium content in the secondary rare earth concentrate is less than 1%, the final pH value needs to be controlled between 3.0 and 4.0.

[0053] Preferably, recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises:

[0054] washing the secondary rare earth concentrate to remove chloride ions in the secondary rare earth concentrate;

[0055] After washing, sulfuric acid is added to the secondary rare earth concentrate and subjected to a sulfate roasting process to recover the rare earths; wherein the sulfate roasting process includes roasting, water leaching, neutralization and impurity removal, and transformation.

[0056] In some embodiments, after the secondary rare earth concentrate obtained by chemical beneficiation is treated by sulfuric acid roasting, the total rare earth recovery rate is greater than 90%.

[0057] In traditional physical mineral processing, sodium carbonate cerium ore will be included in the fluorocarbon cerium ore concentrate. During the subsequent sulfuric acid roasting process, the sodium element in it forms a sulfate complex salt with the rare earth, resulting in a decrease in yield.

[0058] In this embodiment, the sodium carbonate cerium ore associated with the low-grade fluorocarbon cerium ore concentrate is dissolved with dilute acid before sulphation roasting, and then enters into a soluble salt solution containing rare earth and calcium, magnesium, sodium, strontium and barium, so as to solve the problem of reduced yield during sulphation roasting of the concentrate due to the presence of sodium. After sulphation roasting, neutralization and impurity removal are adopted, mainly to remove other non-rare earth impurities, such as iron, phosphorus, radioactive elements, etc.

[0059] When the rare earth grade in the secondary rare earth concentrate is greater than 50% REO, the rare earth can be recovered by oxidative roasting-hydrochloric acid leaching process; when the rare earth grade in the secondary rare earth concentrate is greater than 60% REO, the rare earth can be recovered by alkaline process, both of which have good economic value.

[0060] Preferably, the chloride ion content in the secondary rare earth concentrate after washing is less than 0.5%.

[0061] Studies have found that when the chloride content of secondary rare earth concentrate reaches 0.5% to 2%, the rare earth yield during its sulfuric acid roasting process will be reduced by 1.0 to 2.0%.

[0062] In some embodiments, after the secondary rare earth concentrate is washed, the chloride ion content therein is less than 0.5%, which can effectively reduce the influence of the oxidation-reduction effect of the chloride ions on the sulfation roasting process.

[0063] Preferably, in the process of adding sulfuric acid to the washed secondary rare earth concentrate for sulfation roasting treatment, the mass ratio of the sulfuric acid to the washed secondary rare earth concentrate is 0.9-2.0, the roasting temperature is 150-400° C., and the water immersion temperature is 15-50° C.;

[0064] The neutralization and impurity removal is to use at least one of magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide or magnesium bicarbonate to remove impurities to obtain a rare earth sulfate solution with a pH value of 3.0 to 4.0; wherein the rare earth content in the rare earth sulfate solution is 17 to 45 gREO / L;

[0065] The transformation is to transform the rare earth sulfate solution by rare earth carbonate precipitation or extraction to obtain a rare earth chloride solution.

[0066] In some embodiments, the rare earth chloride solution finally obtained is a rare earth intermediate raw material, which can be directly evaporated and concentrated to obtain a mixed rare earth chloride product or further extracted and separated to obtain a single rare earth or a rare earth enriched product.

[0067] Preferably, recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises:

[0068] The soluble salt solution is precipitated using at least one of sodium carbonate, sodium bicarbonate or ammonium bicarbonate, or the soluble salt solution is extracted using an acidic extractant to recover the rare earth in the soluble salt solution.

[0069] Wherein, the acidic extractant includes but is not limited to at least one of P204 and P507.

[0070] In some embodiments, sodium cerium carbonate ore is dissolved in dilute acid to undergo an acid dissolution reaction to obtain a mixed salt solution containing rare earth, sodium, barium, strontium and calcium, which is a soluble salt solution. The obtained salt solution containing rare earth and sodium, strontium, barium and calcium is directly precipitated or extracted to recover rare earth. With the addition of a precipitant to the soluble salt solution, the rare earth in the soluble salt solution is preferentially precipitated and recovered by filtration, which has the advantages of high rare earth yield and low consumption of chemical raw materials.

[0071] In order to enable those skilled in the art to better understand the present invention, the technical solution of the present invention is further described below through several specific embodiments.

[0072] Example 1

[0073] The raw material is low-grade fluorocarbon cerium ore concentrate with 20.2% REO, in which the rare earth in sodium cerium carbonate accounts for 65.4% of the total rare earth.

[0074] The low-grade fluorocarbon cerium ore concentrate is acid-dissolved with hydrochloric acid at a concentration of 2.0 mol / L, and hydrochloric acid is slowly added to control the reaction temperature at 25°C to 40°C, and the pH value is maintained at about 3.5 and does not change, and then filtered and washed to obtain a secondary rare earth concentrate and a chloride solution containing rare earth, calcium, strontium, barium and sodium. In the chemical beneficiation process, 37.8% of the rare earth in the low-grade fluorocarbon cerium ore concentrate enters the secondary concentrate, and 62.2% of the rare earth enters the chloride solution containing rare earth, calcium, strontium, barium and sodium, and the loss of rare earth can be ignored.

[0075] The obtained secondary rare earth concentrate has a rare earth grade of 42.2% REO, a sodium content of 0.92%, and a chloride ion content of 0.41%. After adding 93% concentrated sulfuric acid in a sulfuric acid: secondary rare earth concentrate mass ratio of 1.2, the mixture is roasted at 320°C, and then water-leached, filtered to obtain a water leaching liquid and a water leaching residue. The water leaching liquid is neutralized and impurities are removed by magnesium oxide to obtain a neutralized residue and a rare earth sulfate solution with a pH value of 3.0-4.0 and a concentration of 28.2 gREO / L, and then ammonium bicarbonate precipitation and hydrochloric acid dissolution (i.e., precipitation transformation) are used to obtain a rare earth chloride solution. From the secondary rare earth concentrate to the rare earth chloride solution, the rare earth yield in the sulfuric acid roasting process is 91.2%.

[0076] First, the obtained chloride solution containing rare earth, calcium, strontium, barium and sodium was analyzed, and the fluoride ion content was 0.09 g / L. Then, sodium carbonate was used for precipitation and filtration to obtain rare earth carbonate and chloride solution containing calcium, strontium, barium and sodium, and then hydrochloric acid was used to dissolve the rare earth carbonate to obtain a rare earth chloride solution.

[0077] In the process of preparing rare earth chloride from the chloride solution containing rare earth, calcium, strontium, barium and sodium, the rare earth yield is 92.1%, and the rare earth is mainly lost in the calcium, strontium, barium and sodium chloride solution after precipitation and filtration. Using the method provided in this embodiment, a rare earth chloride solution is obtained using a low-grade bastnaesite concentrate with 20.2% REO as a raw material, and the total rare earth yield can reach 91.85%.

[0078] Example 2

[0079] The raw material is low-grade fluorocarbon cerium ore concentrate with 20.2% REO, in which the rare earth in sodium cerium carbonate accounts for 65.4% of the total rare earth in the concentrate.

[0080] The low-grade fluorocarbon cerium ore concentrate is acid-dissolved with hydrochloric acid at a concentration of 3.8 mol / L, the reaction temperature is controlled at 80°C, hydrochloric acid is continuously added, and after the pH value is maintained at 3.5 and no longer changes, it is filtered and washed to obtain a secondary rare earth concentrate and a chloride solution containing rare earth, calcium, strontium, barium and sodium. In this chemical beneficiation process, 33.5% of the rare earth in the low-grade fluorocarbon cerium ore concentrate enters the secondary concentrate, and 66.5% enters the chloride solution containing rare earth, calcium, strontium, barium and sodium, and the loss of rare earth can be ignored.

[0081] The obtained secondary rare earth concentrate has a rare earth grade of 48.3% REO, a sodium content of 0.12%, and a chloride ion content of 0.51%. After adding 93% concentrated sulfuric acid in a sulfuric acid: secondary rare earth concentrate mass ratio of 1.2, the mixture is roasted at 280°C, and then water-leached, filtered to obtain a water leaching liquid and a water leaching residue. The water leaching liquid is neutralized and impurities are removed by magnesium oxide to obtain a neutralized residue and a rare earth sulfate solution with a pH value of 3.0-4.0 and a concentration of 29.3 gREO / L, and then ammonium bicarbonate precipitation and hydrochloric acid dissolution (i.e., precipitation transformation) are used to obtain a rare earth chloride solution. From the secondary rare earth concentrate to the rare earth chloride solution, the rare earth yield in the sulfuric acid roasting process is 94.2%.

[0082] First, the obtained chloride solution containing rare earth, calcium, strontium, barium and sodium was analyzed, and the fluoride ion content was 0.32g / L, indicating that part of the fluorocarbon cerium ore was obviously dissolved. Then, the rare earth in the soluble salt solution was extracted and recovered by using P507 extractant, and then the rare earth chloride solution was obtained by hydrochloric acid stripping (i.e., the rare earth was extracted and recovered). It was found that three phases were generated during the extraction process, mainly due to the generation of rare earth fluoride in the extraction section, and the extraction method was difficult to recover rare earth. In the process from the chloride solution containing rare earth, calcium, strontium, barium and sodium to rare earth chloride, the rare earth yield was 87.5%, and the rare earth was mainly lost in the chloride solution of calcium, strontium, barium and sodium and the three phases remaining after the rare earth was extracted.

[0083] By adopting the method provided in the embodiment, a rare earth chloride solution is obtained by taking low-grade bastnaesite concentrate with 20.2% REO as a raw material, and the total rare earth recovery rate can reach 89.74%.

[0084] Compared with Example 1, the reaction temperature during the dilute acid dissolution process is too high, resulting in partial dissolution of the fluorocarbon cerium ore in the chloride solution containing rare earths and calcium strontium barium sodium, resulting in a rare earth recovery rate of less than 90% from the chloride solution containing rare earths and calcium strontium barium sodium, and an overall total recovery rate of less than 90%.

[0085] Example 3

[0086] The raw material is low-grade fluorocarbon cerium concentrate with 38.8% REO, in which the rare earth in sodium cerium carbonate accounts for 39.8% of the total rare earth in the concentrate.

[0087] The low-grade fluorocarbon cerium ore concentrate is subjected to acid dissolution reaction with hydrochloric acid having a concentration of 0.8 mol / L, and hydrochloric acid is slowly added to control the reaction temperature at 25°C to 30°C, and the pH value is maintained at 4.0 and does not change, and then filtered and washed to obtain a secondary rare earth concentrate and a chloride solution containing rare earth, calcium, strontium, barium and sodium. In this chemical beneficiation process, 61.9% of the rare earth in the low-grade fluorocarbon cerium ore concentrate enters the secondary concentrate, and 38.1% of the rare earth enters the chloride solution containing rare earth, calcium, strontium, barium and sodium, and the loss of rare earth can be ignored.

[0088] The obtained secondary rare earth concentrate has 56.2% REO, 0.82% sodium content, and 0.44% chloride ion content. After adding 93% concentrated sulfuric acid in a sulfuric acid: secondary rare earth concentrate mass ratio of 1.4, the mixture is roasted at 160°C, and then water-leached, filtered to obtain water-leaching liquid and water-leaching residue, and the water-leaching liquid is neutralized and impurities are removed by magnesium bicarbonate to obtain neutralized residue and rare earth sulfate solution with a pH value of 3.0-4.0 and a concentration of 18.2 gREO / L, and then sodium bicarbonate precipitation and hydrochloric acid dissolution (i.e., precipitation transformation) are used to obtain rare earth chloride solution. From the secondary rare earth concentrate to the rare earth chloride solution, the rare earth yield in the sulfuric acid roasting process is 94.4%.

[0089] First, the obtained chloride solution containing rare earth and sodium calcium strontium barium is analyzed, wherein the fluoride ion content is 0.08 g / L, and then rare earth carbonate and a chloride solution containing sodium calcium strontium barium are obtained after precipitation and filtration using ammonium bicarbonate, and then the rare earth carbonate is dissolved in hydrochloric acid to obtain a rare earth chloride solution. In the process of converting the chloride solution containing rare earth and sodium calcium strontium barium to rare earth chloride, the rare earth yield is 92.2%, and the rare earth is mainly lost in the chloride solution of sodium calcium strontium barium after precipitation.

[0090] By adopting the method provided in the embodiment, a rare earth chloride solution is obtained by taking low-grade bastnaesite concentrate with 38.8% REO as a raw material, and the total rare earth recovery rate can reach 93.56%.

[0091] Example 4

[0092] The raw material is low-grade fluorocarbon cerium concentrate with 38.8% REO, in which the rare earth in sodium cerium carbonate accounts for 39.8% of the total rare earth in the concentrate.

[0093] The low-grade fluorocarbon cerium ore concentrate is subjected to an acid dissolution reaction using hydrochloric acid with a concentration of 2.0 mol / L, and hydrochloric acid is slowly added to control the reaction temperature at 20°C, and the pH value is maintained at about 3.5 and does not change, and then filtered and washed to obtain a secondary rare earth concentrate and a chloride solution containing rare earth, calcium, strontium, barium and sodium. In this chemical beneficiation process, 60.6% of the rare earth in the low-grade fluorocarbon cerium ore concentrate enters the secondary concentrate, and 39.4% of the rare earth enters the chloride solution containing rare earth, calcium, strontium, barium and sodium, and the loss of rare earth can be ignored.

[0094] The obtained secondary rare earth concentrate has 59.5% REO, 0.52% sodium content and 0.44% chloride ion content. After adding 93% concentrated sulfuric acid in a sulfuric acid: secondary rare earth concentrate mass ratio of 1.05, the mixture is roasted at 345°C, then water-leached, filtered to obtain water-leaching liquid and water-leaching residue, the water-leaching liquid is neutralized and impurities are removed by magnesium bicarbonate, and neutralized residue and rare earth sulfate solution with a pH value of 3.0-4.0 and a concentration of 19.2 gREO / L are obtained, and then ammonium bicarbonate is used for precipitation and hydrochloric acid dissolution (i.e., precipitation transformation) to obtain rare earth chloride solution. From the secondary rare earth concentrate to the rare earth chloride solution, the rare earth yield in the process of sulfuric acid roasting method is 95.2%.

[0095] First, the obtained chloride solution containing rare earth and calcium, strontium, barium and sodium was analyzed, wherein the fluoride ion content was 0.03 g / L, and then rare earth carbonate and a chloride solution containing calcium, strontium, barium and sodium were obtained after precipitation and filtration using ammonium bicarbonate, and then the rare earth carbonate was dissolved in hydrochloric acid to obtain a rare earth chloride solution.

[0096] In the process of preparing rare earth chloride from the chloride solution containing rare earth, calcium, strontium, barium and sodium, the rare earth yield is 94.1%, and the rare earth is mainly lost in the chloride solution of calcium, strontium, barium and sodium after precipitation. By adopting the method provided in the embodiment, the rare earth chloride solution is obtained using low-grade bastnaesite concentrate with 38.8% REO as raw material, and the total rare earth yield can reach 94.8%.

[0097] Comparative Example 1 (Comparative Example of Embodiments 1 and 2)

[0098] The raw material is low-grade fluorocarbon cerium ore concentrate with 20.2% REO, in which the rare earth in sodium cerium carbonate accounts for 65.4% of the total rare earth.

[0099] 93% concentrated sulfuric acid is added to the low-grade fluorocarbon cerium ore concentrate in a mass ratio of 1.89, and the mixture is roasted at 320°C, then water-leached and filtered to obtain a water-leaching liquid and water-leaching residue. The water-leaching liquid is neutralized and impurities are removed by magnesium oxide and then filtered to obtain neutralized residue and a rare earth sulfate solution with a pH value of 3.0-4.0 and a concentration of 26.2 gREO / L, and then P204 is used for extraction and transformation to obtain a rare earth chloride solution.

[0100] Using low-grade bastnaesite concentrate with 20% REO as raw material, the rare earth chloride solution is directly obtained by sulfuric acid roasting method, and the rare earth yield is only 78.2%. The rare earth is mainly lost in the acid soluble slag and neutralization slag produced during the sulfuric acid roasting process.

[0101] Therefore, by comparing Comparative Example 1, Example 1 and Example 2, the use of chemical beneficiation treatment for low-grade bastnaesite concentrate from the low-grade bastnaesite concentrate to the rare earth chloride solution will greatly increase the total rare earth recovery.

[0102] For the method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should know that the present invention is not limited by the order of the actions described, because according to the present invention, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also know that the embodiments described in the specification are all preferred embodiments, and the actions and components involved are not necessarily required by the present invention.

[0103] The above is a detailed introduction to the chemical beneficiation method of a low-grade fluorocarbon cerium ore concentrate provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea; at the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation method and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A chemical beneficiation method for low-grade bastnaesite concentrate, characterized in that: The low-grade bastnaesite concentrate contains at least two minerals, bastnaesite and cerium carbonate ore, and the rare earth grade in the low-grade bastnaesite concentrate is 15% to 40% REO. The method comprises: Dissolving low-grade bastnaesite concentrate with dilute acid, so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain a soluble salt solution; wherein the soluble salt solution contains rare earth and calcium, strontium, barium and sodium; Recovering rare earths from the soluble salt solution and the secondary rare earth concentrate; wherein the rare earth minerals in the secondary rare earth concentrate are substantially composed of the bastnasite that is insoluble in dilute acid; Wherein, the dilute acid is at least one of hydrochloric acid, acetic acid or nitric acid; The concentration of the dilute acid is 0.5-4.0 mol / L; The low-grade fluorocarbon cerium ore concentrate is dissolved with dilute acid, and the temperature is controlled at 20-35° C. so that the sodium cerium carbonate ore is dissolved in the dilute acid to obtain the soluble salt solution.

2. The chemical mineral processing method according to claim 1, characterized in that: The rare earth in the sodium carbonate cerium ore accounts for 10% to 80% of the total rare earth in the low-grade bastnaesite concentrate; the rare earth grade in the secondary rare earth concentrate is 40% to 70% REO.

3. The chemical mineral processing method according to claim 1, characterized in that: The pH value of the soluble salt solution is 3.0-4.

0.

4. The chemical mineral processing method according to claim 1, characterized in that: Recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises: washing the secondary rare earth concentrate to remove chloride ions in the secondary rare earth concentrate; After washing, sulfuric acid is added to the secondary rare earth concentrate and subjected to a sulfate roasting process to recover the rare earths; wherein the sulfate roasting process includes roasting, water leaching, neutralization and impurity removal, and transformation.

5. The chemical mineral processing method according to claim 4, characterized in that: After washing, the chloride ion content in the secondary rare earth concentrate is less than 0.5%.

6. The chemical mineral processing method according to claim 4, characterized in that: In the process of adding sulfuric acid to the washed secondary rare earth concentrate for sulphate roasting treatment, the mass ratio of the sulfuric acid to the washed secondary rare earth concentrate is 0.9-2.0, the roasting temperature is 150-400° C., and the water immersion temperature is 15-50° C.; The neutralization and impurity removal is to use at least one of magnesium oxide, calcium oxide, magnesium hydroxide, calcium hydroxide or magnesium bicarbonate to remove impurities to obtain a rare earth sulfate solution with a pH value of 3.0 to 4.0; wherein the rare earth content in the rare earth sulfate solution is 17 to 45 gREO / L; The transformation is to transform the rare earth sulfate solution by rare earth carbonate precipitation or extraction to obtain a rare earth chloride solution.

7. The chemical mineral processing method according to claim 1, characterized in that: Recovering rare earths from the soluble salt solution and the secondary rare earth concentrate comprises: The soluble salt solution is precipitated using at least one of sodium carbonate, sodium bicarbonate or ammonium bicarbonate, or the soluble salt solution is extracted using an acidic extractant to recover the rare earth in the soluble salt solution.

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