Feldspar is a family of minerals consisting of potassium, sodium, calcium and barium aluminosilicate composition, it is the most common mineral in the earth's crust, the proportion of 60%, can be found in igneous, metamorphic rocks, sedimentary rocks. Feldspar has a melting point between 1100 and 1300 ° C. It has good chemical stability and has a fluxing effect when co-melting with quartz and aluminosilicate. It is often used to make flux for glass and ceramic glaze, and can be reduced. The firing temperature; in addition, the formation of the feldspar glass body can also improve the light transmittance of the green body [1] . Practice has confirmed that the content of iron , calcium and other elements in feldspar determines the quality of ceramic products, iron content is too high, black spots appear in the products, calcium (mainly in the presence of carbonates) is too high, burning The finished product will have uneven pores, so the content of iron and calcium must be reduced in the feldspar purification process.
Generally feldspar, quartz, mica, calcite, clay minerals rutile and symbiosis. There are two main forms of iron. One is in free minerals such as red iron iron ore, the other is in mica minerals, and the calcium is mainly in calcite. The red limonite can pass high gradient magnetic separation. Removal, mica minerals can be removed by high gradient magnetic separation and flotation, and calcite is mainly removed by flotation.
First, the experimental part
(1) Ore properties
The ore sample is a feldspar mine in Shandong. The multi-element analysis results (wt%) of the ore are: Si0 2 , 68.68; A1 2 0 3 , 17.37; TFe 2 0 3 , 0.34; MgO, 0.15; CaO, 1.02; 2 0,6.05; K 2 0,4.64; Ti0 2 , 0.11; P 2 0 5 , 0.04; MnO, 0.02; H 2 0 - , 0.11; loss on ignition, 1.47. The Na 2 0+K 2 0 in the ore is 10.69%, which is lower than the 11% feldspar first grade standard, and the TFe 2 0 3 content is 0.34%, which is higher than 0.2% of the first grade standard, and the CaO content is 1.02%. Also higher than 1.0% of the first grade standard.
According to XRD analysis, the main components of the ore are 49% albite, 16% potassium feldspar, 18% quartz and 9% of mica minerals, and a small amount of chervetite, rutile and zircon . Iron minerals are present in biotite, and a small amount of iron is present as a free single mineral in chernorite.
After the classification of ore grinding, the distribution of iron and calcium in each grade product was analyzed. It was found that iron-bearing minerals and calcite were mainly distributed in the fine-grained grade, and further enriched as the particle size became finer. Set in the fine fraction of -0.030mm or less.
(2) Experimental drugs and instruments
Experimental agents: fatty acid salt collectors , water glass, sodium carbonate, sulfuric acid, amine cation collectors, non-polar oils (both commercially available).
Experimental equipment: XMB-70 three-roller four-cylinder grinding machine, Hubei Prospecting Machinery Plant; Slon-100 periodic pulsating high-gradient magnetic separator, Jiangxi Luzhou Institute of Metallurgy; RK/FD type 1L single-tank flotation machine, Wuhan Locke Crushing Equipment Manufacturing Co., Ltd.; XTLZφ260/φ200 multi-purpose vacuum filter, Xichang 102 factory.
(3) Determination of grinding fineness
Under the condition of grinding concentration of 50%, the grinding time is changed and the grinding classification test is carried out. The product is divided into three grades: +0.074mm, -0.074mm+0.045mm and -0.045mm. The grinding time is 8 min, 10 min, 12 min, 14 min and 16 min respectively, and the XMB-70 three-roll four-cylinder grinding machine is used for grinding. The test results are shown in Table 1 and Figure 1.
It can be seen from Table 1 and Figure 1 that when the grinding time is increased from 8 min to 10 min, the grinding fineness does not change much; from 10 min to 12 min, the content of -0.074 mm increases significantly, reaching 63.68%, and continues to increase the grinding. The mining time, the fineness curve of the grinding tends to be stable, and the trend of increasing the content of -0.074 mm and -0.045 mm gradually becomes smaller.
The grinding fineness is determined by the whole process test. The test flow is shown in Figure 2, and the test results are shown in Table 2. The mixed collector is a compound collector of an amine and a non-polar oil.
It can be seen from Table 2 that as the grinding time increases, the concentrate yield gradually decreases. After the grinding time exceeds 12 minutes, the yield decreases significantly, so the grinding time should not be too long. The removal rate of iron increased gradually with the increase of grinding time, and the removal rate of calcium did not change much. When the grinding time was 12 min, the content of iron and calcium in the concentrate was 0.13% and 0.25%, respectively, and the grinding time was increased. The indicator does not change much, but it will increase the grinding power consumption and reduce the concentrate yield. Considering comprehensively, it is determined that the grinding time is 12 min, that is, the grinding fineness is -0.074 mm 63.68%.
(4) Determination of sedimentation time
According to the analysis of the distribution of iron and calcium in the ore, it is known that Fe 2 O 3 and CaO are mainly distributed in the fine mud below -0.030 mm, and the fine mud of -0.030 mm is removed, which can effectively reduce the iron and calcium in the concentrate. The content, so the deliming operation is carried out before the selection.
In order to remove the fine-grained grade sludge of the -0.030 m class, the settling time was determined to be 6 min according to the Stokes settlement formula.
(5) Magnetic field strength test
The magnetic separation adopts Slon-100 periodic pulsation high gradient magnetic separator. Under the conditions determined by grinding fineness and sedimentation time, the magnetic separation condition is determined as follows: magnetic pulsation rises and falls, water flow pulsation is 400 times/min, pulp The flow rate was 0.8 cm/s and the field strengths were 0.7T, 0.8T, 0.9T and 1.0T, respectively. The test results are shown in Table 3.
The test results show that with the increase of field strength, the Fe 2 0 3 content in the concentrate gradually decreases, and the iron removal rate is higher and higher. When the magnetic field strength is 0.9T, the concentrate TFe 2 0 3 content is 0.25%, iron. The removal rate was 38.12%, and the field strength was increased. The content of TFe 2 0 3 and the removal rate of iron in the concentrate did not change much, so the magnetic field strength was determined to be 0.9T.
(6) Test of flotation conditions of calcite
The flotation adopts the RK/FD type 1L single-tank flotation machine produced by Wuhan Locke Equipment Manufacturing Co., Ltd. The calcium element in the feldspar mine is mainly contained in calcite. It has been proved that the fatty acid salt collector can float the calcite well. Under the activation of calcium ions or strontium ions, it can also float quartz for suppression. The flotation of quartz can add water glass to increase the hydrophilicity of gangue minerals such as quartz, and inhibit it from floating up with bubbles. The test conducted a condition test of a pH adjuster, an inhibitor, and a collector. The pH adjuster uses Na 2 CO 3 , the collector uses a fatty acid salt, and the inhibitor uses water glass. The test flow is shown in Figure 3.
1. pH adjuster condition test: Under the conditions that the grinding fineness, sedimentation deslimping time and magnetic separation field strength have been determined, the amount of fatty acid salt is determined to be 1200g/t, and the amount of water glass is 80g/t. The pH adjuster condition test was carried out using the amount of Na 2 CO 3 . The test results are shown in Table 4.
The results show that the content of CaO and TFe 2 0 3 in the concentrate does not change much with the increase of Na 2 CO 3 dosage. When the amount of Na 2 CO 3 is 1200g/t, the content of CaO in the concentrate is 0.23%, and the removal rate of calcium is the highest, which is 82.87%. Then the amount of Na 2 CO 3 is increased, and the removal rates of iron and calcium are all As a result of the decrease, it was determined that the amount of Na 2 CO 3 was 1200 g/t, and the pH was 8 at this time.
2. Inhibitor condition test: Determine the amount of Na 2 CO 3 to be 1200 g/t, change the amount of water glass, and carry out the inhibitor condition test. The amount of water glass is 0g/t, 40g/t, 80g/t and 120g/t. The test results are shown in Table 5.
The test results show that the removal rate of iron and calcium is not changed much, and the amount of water glass is increased. The content of TFe 2 0 3 and CaO in the final concentrate is almost unchanged. Increasing the amount of inhibitor does not significantly improve the flotation effect of calcite. Therefore, it is not recommended to add inhibitor water glass.
3. Collector test: Under the condition that no inhibitor is added, the amount of fatty acid salt is changed, and the conditions of the collector are tested. The dosages are 500g/t, 1000g/t, 1500g/t and 2000g/t, respectively. The test results are shown in Table 6.
The test results show that with the increase of the amount of collector, the iron and calcium content in the concentrate gradually decreases. When the dosage of the collector exceeds 1500g/t, the removal rate of iron and calcium does not change much. The flotation effect was used to determine the amount of collector to be 1500 g/t.
(VII) Test of flotation conditions of mica
Most of the iron elements in the feldspar mine are enriched in mica minerals. In order to reduce the TFe 2 0 3 content in the minerals, the mica minerals must be removed.
Mica is a silicate mineral with a layered structure. The surface is highly negative in water and has a low zero point. When using cationic collector flotation, mica has a good floatability in a wide pH range. Sex. The test used a mixed collector of amine and non-polar oil, and H 2 SO 4 as a pH adjuster, and the conditions were tested separately. The test flow is shown in Figure 4.
pH adjusting agent (H 2 SO 4 ) condition test: Under the conditions that the grinding fineness, sedimentation deslimping time, magnetic separation field strength and flotation calcite dosage have been determined, the amount of collector is determined to be 1600g/t. The amount of H 2 SO 4 was changed to carry out the pH adjuster condition test, and the amounts of H 2 SO 4 were 1000 g/t, 1500 g/t, 2000 g/t and 2500 g/t, respectively, and the test results are shown in Table 7.
The results show that with the increase of H 2 SO 4 dosage, the iron removal rate increases first and then decreases, and the calcium removal rate is relatively stable. When the dosage is 2000g/t, the content of TFe 2 0 3 in the concentrate is the lowest, 12%, iron. The removal rate is the highest, which is 79.86%. Then the amount of H 2 SO 4 is increased. The content of TFe 2 0 3 in the concentrate increases, the removal rate of iron decreases, and the final concentrate contains more feldspar, which indicates that when the pH is lower than 3.5. The collector's effect on the recovery of mica is reduced. Considering the comprehensive consideration, it is determined that the amount of H 2 SO 4 is 2000 g/t, and the pH value is 3.5.
(8) Collector test
The amount of H 2 SO 4 was determined to be 2000 g/t, and the amount of the mixed collector was changed to carry out the condition test of the collector. The test results are shown in Table 8.
The test results show that with the increase of the amount of collector, the concentrate yield and TFe 2 0 3 gradually decrease. When the dosage exceeds 160g/t, the content of TFe 2 0 3 in the concentrate does not change much, and the removal of iron and calcium The rate is relatively stable. Considering comprehensively, the amount of collector is determined to be 160g/t.
Second, the recommended process
Through the grinding fineness determination test, sedimentation desilting test, magnetic separation field strength test, condition test of anti-floating calcite and condition test of anti-floating mica, the best test process was determined. The results are shown in Fig. 5.
Under the recommended process, the final process can be obtained by the whole process test: Na 2 0+K 2 0 content is 11.05%, TFe 2 0 3 is 0.12%, CaO is 0.26%, and all three indicators are long. The quality standard of stone first grade products.
Under the recommended procedure, the cost of the chemicals required to process the unit mass (1t) of raw ore is estimated. The price of each flotation agent is shown in Table 9.
Third, the conclusion
(1) The composition of the feldspar mine is albite, potassium feldspar, mica, quartz, calcite, and a small amount of red limonite, rutile and zircon. The iron-bearing and calcium minerals are mainly distributed in the fine-grained grade, in which iron is mainly distributed in biotite and red limonite, and calcium is mainly present in calcite.
(2) It is determined by grinding fineness test that the ore fineness of the ore is -0.074mm63.68%;
(3) By removing the mud, the iron and titanium minerals in the fine-grained grade of -0.030mm can be effectively removed, the difficulty of sorting in subsequent operations is reduced, the quality of the concentrate is improved, and the sedimentation time is determined to be 6 min;
(4) The field strength was determined to be 0.9T by magnetic field strength test.
(5) Through the conditional test of calcite flotation, the optimal agent system for flotation was determined as follows: the pH adjuster Na 2 CO 3 dosage was 1200 g/t, and the fatty acid salt collector was 1500 g/t.
(6) Through the conditional test of mica flotation, the optimal agent system for flotation was determined as follows: the pH adjuster H 2 SO 4 dosage is 2000g/t, and the mixed collector of amine and non-polar oil is 160g. /t.
references
[1] Gao Huimin, Yuan Jizu, Zhang Lingyan, et al. Experimental study on feldspar iron removal [J]. Chinese Ceramics, 2006, 42(4): 46-48.
[2] Dai Qiang, Tang Jiaying. Progress in quartz-feldspar flotation separation [J]. Non-metallic minerals, 1997 (2): 16-21.
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