A low-grade phosphate ore direct-reverse flotation process and an intelligent dosing system

Abstract

The application discloses a kind of low-grade phosphate rock direct and reverse flotation process and intelligent dosing system, process includes rough grinding pre-decarbonization, regrinding direct flotation, reverse flotation optimization etc., with carboxymethyl starch and phosphatized chitosan composite depressor inhibiting phosphate mineral;Intelligent dosing system is based on XRF online detection MgO / P2O5 ratio, dynamically adjusts the amount of depressor, realizes accurate control.The low-grade phosphate rock direct and reverse flotation process provided by the application can significantly improve the removal rate of MgO, reduce the cost of reagent, reduce the loss of fine mud, optimize energy consumption, dynamic intelligent dosing system responds to ore fluctuation, improves the stability of concentrate MgO, suitable for efficient separation of low-grade phosphate rock, with industrial application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mineral processing, in particular to a positive and reverse flotation process for medium and low grade phosphate rock and an intelligent dosing system. BACKGROUND

[0002] The positive and reverse flotation of medium and low grade phosphate rock is a beneficiation process developed for the refractory siliceous and calcareous phosphate rock (P2O5 15-25%, MgO 3-8%) in China. The core significance lies in efficient utilization of low grade resources that are difficult to be processed by traditional technology, and solving the structural contradiction of "more lean ore and less rich ore" in China's phosphate rock. The process usually recovers phosphate minerals through positive flotation first, and then removes silicon, magnesium and other impurities through reverse flotation, finally obtaining high quality phosphate concentrate (P2O5 > 30%, MgO < 0.8%) meeting the requirements of phosphate fertilizer production.

[0003] Currently, the positive and reverse flotation technology for medium and low grade phosphate rock faces certain technical bottlenecks, such as poor selectivity due to similar surface properties of minerals, waste of reagents caused by the need for multiple reagents stacking, and large energy consumption of process equipment, etc. Therefore, an improved positive and reverse flotation process for medium and low grade phosphate rock is needed to solve the above technical problems. SUMMARY

[0004] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0005] On the one hand, the present application provides a positive and reverse flotation process for medium and low grade phosphate rock, comprising the following steps:

[0006] a) Coarse grinding of phosphate rock ore to a particle size of ≤0.3mm, and pre-decarbonization flotation to remove carbonate gangue minerals;

[0007] b) Positive flotation of the slurry treated by step a) to obtain positive flotation rough concentrate, and then regrinding to a particle size of <0.074mm with a cumulative content of ≥80%;

[0008] c) Magnesium removal by reverse flotation of the positive flotation rough concentrate regrinded by step b), using carboxymethyl starch and phosphatized chitosan composite inhibitor to inhibit phosphate minerals, and the amount of the composite inhibitor is adjusted by the MgO / P2O5 ratio of the slurry entering the reverse flotation operation.

[0009] Preferably, the pre-decarbonization flotation in step a) is carried out at pH 6.0-6.5, and modified sodium humate 0.5-1.0kg / t is used as collector and foaming agent.

[0010] Preferably, the reverse flotation collector in step c) is a compound of fatty acid and sulfonate in a mass ratio of (2.5-3.5):1, which is used to collect magnesium-containing gangue minerals.

[0011] Preferably, the total amount of collector in step c) is 0.8-1.2 kg / t, and the pH of the flotation is 9.0-10.0.

[0012] Preferably, the carboxymethyl starch in the composite inhibitor in step c) accounts for 60-70 wt%, and the phosphorylated chitosan accounts for 30-40 wt%, the degree of substitution of the phosphorylated chitosan is ≥0.25, and the characteristic infrared absorption peak is 1240 cm -1 and 1050 cm -1 .

[0013] More preferably, the degree of substitution of the phosphorylated chitosan in the composite inhibitor is 0.25-0.35, and the molecular weight is 50,000-100,000 Da.

[0014] In another aspect, the present application provides an intelligent dosing system, comprising an XRF online analyzer, a reagent storage tank, a servo flow controller, and a dynamic calculation module, the dynamic calculation module calculates the amount of inhibitor according to the formula:

[0015] Q = k×(MgO / P2O5)+b

[0016] , wherein k=1.2-1.8 and b=0.1-0.3.

[0017] Preferably, the XRF online analyzer detects the MgO / P2O5 ratio of the ore pulp entering the reverse flotation operation in step c) in real time, when the MgO / P2O5 ratio is 0.15-0.25, the intelligent dosing system adjusts the amount of composite inhibitor to be in the range of 0.3-0.4 kg / t, when the MgO / P2O5 ratio is 0.25-0.35, the amount of composite inhibitor is adjusted to be in the range of 0.4-0.6 kg / t, and the amount of composite inhibitor increases in a stepwise manner with the increase of the MgO / P2O5 ratio.

[0018] Preferably, the intelligent dosing system is provided with a feedback module, which can automatically correct the coefficients k and b according to the MgO content of the concentrate.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] (1) The positive and reverse flotation process for medium and low grade phosphate ore provided by the present application can significantly improve the removal rate of MgO, and the MgO content of the concentrate obtained is ≤0.8%, and the process can be applied to high-magnesium ore (MgO 6-8%);

[0021] (2) The positive and reverse flotation process for medium and low grade phosphate ore provided by the present application uses a small amount of reagents, and the amount of reagents can be adjusted, which can significantly reduce the cost of reagents and reduce the waste of reagents;

[0022] (3) The positive and reverse flotation process for medium and low grade phosphate ore provided by the application reduces the content of 38 mu mud in the finished concentrate to less than or equal to 15%, while reducing the loss rate of the mud;

[0023] (4) The positive and reverse flotation process for medium and low grade phosphate ore provided by the application includes two grinding steps of rough grinding and regrinding, which significantly reduces the total grinding energy consumption compared with the traditional one-step grinding;

[0024] (5) The intelligent dosing system provided by the application can dynamically respond to ore fluctuations and improve the stability of the MgO content in the concentrate.

[0025] (6) The application is suitable for efficient separation of medium and low grade phosphate ore (P2O5 15-25%, MgO 3-8%) and has industrial application prospects. DETAILED DESCRIPTION

[0026] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments of the application. Based on the embodiments in the application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of the application.

[0027] Example 1

[0028] A positive and reverse flotation process for medium and low grade phosphate ore includes the following steps:

[0029] a) Coarse grinding of phosphate ore raw ore (P2O5 19.3%, MgO 6.8%) to a particle size of less than or equal to 0.3 mm, adding 0.7 kg / t of sodium humate, adjusting the pH to 6.3, and performing pre-decarbonization flotation to remove carbonate gangue minerals;

[0030] b) Positive flotation of the slurry treated in step a) is performed, using 0.4 kg / t of carboxymethyl starch and 0.25 kg / t of phosphatized chitosan as inhibitors, to obtain a positive flotation rough concentrate, and regrinding to a cumulative particle size of less than 0.074 mm = 80%;

[0031] c) Reverse flotation of the positive flotation rough concentrate regrinded in step b) is performed to remove magnesium-containing gangue minerals, and the reverse flotation collector is a compound of fatty acid and sulfonate in a mass ratio of 3:1, with a total dosage of 1.0 kg / t, and the flotation pH is 9.6; at the same time, a composite inhibitor of carboxymethyl starch (accounting for 67 wt%) and phosphatized chitosan (accounting for 33 wt%, with a degree of substitution of 0.31 and a molecular weight of about 85,000 Da, and characteristic infrared absorption peaks at 1240 cm -1 and 1050 cm -1 ) is used to inhibit phosphate minerals.

[0032] An intelligent reagent adding system is used in step c), which comprises an XRF on-line analyzer, a reagent storage tank, a servo flow controller, and a dynamic calculation module, which calculates the amount of the depressant according to the formula: Q = k × (MgO / P2O5) + b, wherein k = 1.2-1.8 and b = 0.1-0.3.

[0033] The XRF on-line analyzer detects the MgO / P2O5 ratio of the ore slurry entering the reverse flotation operation in step c) in real time. When the MgO / P2O5 ratio is in the range of 0.15-0.25, the intelligent reagent adding system adjusts the amount of the depressant to be in the range of 0.3-0.4 kg / t; when the MgO / P2O5 ratio is in the range of 0.25-0.35, the amount of the depressant is adjusted to be in the range of 0.4-0.6 kg / t; and the amount of the depressant increases in a stepwise manner with the increase of the MgO / P2O5 ratio. The intelligent reagent adding system is also provided with a feedback module, which can automatically correct the coefficients k and b according to the MgO content of the concentrate.

[0034] Example 2

[0035] The difference from Example 1 is that 0.5 kg / t of sodium humate is added in step a) to adjust the pH to 6.0; the reverse flotation collector in step c) is a compound of fatty acid and sulfonate with a mass ratio of 2.5:1, and the total amount of the collector is 0.8 kg / t, and the flotation pH is 9.0; and a compound depressant of carboxymethyl starch (60 wt%) and phosphonated chitosan (40 wt%, degree of substitution 0.25, molecular weight about 50,000 Da, characteristic infrared absorption peaks at 1240 cm -1 and 1050 cm -1 ) is used to depress the phosphate minerals.

[0036] The rest is the same as in Example 1.

[0037] Example 3

[0038] The difference from Example 1 is that 1.0 kg / t of sodium humate is added in step a) to adjust the pH to 6.5; the reverse flotation collector in step c) is a compound of fatty acid and sulfonate with a mass ratio of 3.5:1, and the total amount of the collector is 1.2 kg / t, and the flotation pH is 10.0; and a compound depressant of carboxymethyl starch (70 wt%) and phosphonated chitosan (30 wt%, degree of substitution 0.35, molecular weight about 100,000 Da, characteristic infrared absorption peaks at 1240 cm -1 and 1050 cm -1 ) is used to depress the phosphate minerals.

[0039] The rest is the same as in Example 1.

[0040] Example 4

[0041] The difference from Example 1 is that: the phosphorite ore crude component contains P2O522.1%, MgO 3.2% in step a).

[0042] The rest is the same as Example 1.

[0043] Comparative Example 1

[0044] The difference from Example 1 is that: only carboxymethyl starch is used as inhibitor in step c).

[0045] The rest is the same as Example 1.

[0046] Comparative Example 2

[0047] The difference from Example 1 is that: no intelligent dosing system is used in step c).

[0048] The rest is the same as Example 1.

[0049] Comparative Example 3

[0050] The difference from Example 1 is that: one-stage grinding method is used in step a) to grind to a particle size of ≤0.074 mm; no regrinding is performed in step b).

[0051] The rest is the same as Example 1.

[0052] Performance Testing

[0053] The MgO content of the concentrates prepared by the processes described in Examples 1-4 and Comparative Examples 1-3 is determined, and the P2O5 recovery rate and 38 μm fine slime loss rate are calculated. The test results are shown in Table 1.

[0054] Table 1

[0055]

[0056] Comparing Comparative Examples 1-3, the MgO content of the concentrate and the P2O5 recovery rate of Example 1 are relatively higher than those of Examples 2 and 3. The reagent cost per ton of ore of Example 2 is lower than that of Examples 1 and 3, mainly because the amount of collector used is the lowest, and the proportion of carboxymethyl starch in the inhibitor is the smallest. The 38 μm fine slime loss rate of Example 3 is higher than that of Example 1, mainly because the amount of collector used is the highest, and the proportion of carboxymethyl starch in the inhibitor is the largest, so the fine slime loss rate is relatively lower, but the reagent cost per ton of ore is higher.

[0057] Comparative Example 1 and Example 4, because the MgO content of the raw ore in Example 4 is relatively lower, the MgO content of the concentrate prepared is relatively lower, the P2O5 recovery rate is higher, and the fine mud loss rate and the ton ore reagent cost are also lower.

[0058] Comparative Example 1 and Comparative Examples 1-3, the MgO content of the concentrate prepared in Example 1 is the lowest, the P2O5 recovery rate is the highest, and the fine mud loss rate and the ton ore reagent cost are also the lowest, proving that the carboxymethyl starch and phosphonated chitosan used in Example 1 and the intelligent reagent adding system and the two-stage grinding method synergize, significantly improving the working efficiency and economic efficiency of the direct and reverse flotation of medium and low grade phosphate ore.

[0059] Although the present application has been described in detail by preferred embodiments, the present application is not limited thereto. Various equivalent modifications or replacements of the embodiments of the present application can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and replacements shall be within the scope of the present application. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or replacements, which shall be covered within the protection scope of the present application.

Claims

1. A forward and reverse flotation process for medium- and low-grade phosphate rock, characterized in that, Includes the following steps: a) Coarsely grind the phosphate rock ore to a particle size ≤0.3mm and perform pre-decarbonization flotation to remove carbonate gangue minerals; b) Perform direct flotation on the slurry treated in step a) to obtain direct flotation rough concentrate, and then grind it until the cumulative content of particles smaller than 0.074 mm is ≥80%; c) The rough concentrate from the direct flotation process, after fine grinding in step b), is subjected to reverse flotation to remove magnesium. A composite inhibitor of carboxymethyl starch and phosphorylated chitosan is used to suppress phosphate minerals. The amount of the composite inhibitor is adjusted by the MgO / P2O5 ratio of the pulp entering the reverse flotation process. The composite inhibitor contains 60-70 wt% carboxymethyl starch and 30-40 wt% phosphorylated chitosan, with a degree of substitution ≥0.25 and a characteristic infrared absorption peak at 1240 cm⁻¹. -1 and 1050cm -1 .

2. The forward and reverse flotation process for medium- and low-grade phosphate rock according to claim 1, characterized in that, The pre-decarbonization flotation described in step a) is carried out at pH 6.0-6.

5.

3. The forward and reverse flotation process for medium- and low-grade phosphate rock according to claim 1, characterized in that, In step a), 0.5-1.0 kg / t of modified sodium humate is used as a collector and foaming agent.

4. The forward and reverse flotation process for medium- and low-grade phosphate rock according to claim 1, characterized in that, The reverse flotation collector mentioned in step c) is a mixture of fatty acids and sulfonates in a mass ratio of (2.5-3.5):

1.

5. The forward and reverse flotation process for medium- and low-grade phosphate rock according to claim 4, characterized in that, In step c), the total amount of collector used is 0.8-1.2 kg / t, and the flotation pH is 9.0-10.

0.

6. The forward and reverse flotation process for medium- and low-grade phosphate rock according to claim 1, characterized in that, The degree of substitution of phosphorylated chitosan in the composite inhibitor is 0.25-0.35, and the molecular weight is 50,000-100,000 Da.

7. An intelligent dosing system for controlling the dosage of composite inhibitor in step c) of the medium-low grade phosphate rock forward and reverse flotation process according to any one of claims 1-6, comprising an XRF online analyzer, a reagent storage tank, a servo flow controller, and a dynamic calculation module, characterized in that, The dynamic calculation module is based on the formula: Q = k×(MgO / P2O5)+b Calculate the dosage of the compound inhibitor, where k = 1.2-1.8 and b = 0.1-0.

3.

8. The intelligent dosing system according to claim 7, characterized in that, The XRF online analyzer monitors the MgO / P2O5 ratio of the slurry entering the reverse flotation operation in real time during step c). When the MgO / P2O5 ratio is between 0.15 and 0.25, the intelligent dosing system adjusts the dosage of the composite inhibitor to 0.3-0.4 kg / t. When the MgO / P2O5 ratio is between 0.25 and 0.35, the dosage of the composite inhibitor is adjusted to 0.4-0.6 kg / t. The dosage of the composite inhibitor increases in a stepwise manner as the MgO / P2O5 ratio increases.

9. The intelligent dosing system according to claim 7, characterized in that, The intelligent dosing system is equipped with a feedback module, which can automatically correct coefficients k and b based on the MgO content of the concentrate.

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