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Process technology of removing phosphorus and manganese from high phosphorus and low manganese refractory ore
China is a country rich in manganese ore resources of the country, as early as 1960 has proven ore reserves second only to the former Soviet Union and India, the door to the world. With the rapid development of industry, the metal manganese requirements increase, diminishing rich manganese, manganese ore metallurgical products of various electrode, in addition to the requirements for the content of manganese in the ore, the ratio of iron to manganese, phosphorus ratio of manganese, The content of silica has specific strict requirements, while manganese for military, chemical, and battery uses high-quality manganese concentrate with lower impurity content. However, due to the complex structure of low-manganese ore, the size of the inlaid cloth is fine, and it contains high impurity (phosphorus, sulfur, iron, silicon, etc.), which makes it difficult to select and utilize manganese ore. In particular, the impurity phosphorus exists in the form of amorphous colloidal phosphate in the form of molten sol-like state in the manganese-bearing ore. At present, the use of mechanical beneficiation methods to remove phosphorus and improve the manganese ore grade can not achieve satisfactory results.
In order to make full use of mineral resources and improve the industrial utilization value of the manganese deposit, the process of combining mechanical beneficiation and chemical beneficiation to remove impurities and improve the grade of manganese ore has long attracted the attention of domestic and foreign mineral processing workers.
This paper discusses the characteristics of manganese and phosphorus removal process in high phosphorus and low manganese ore in a certain area of ​​Shaanxi.
First, the nature of the ore
The mine is a sedimentary manganese-containing carbonate ore. The ore contains low manganese (11%), high impurity phosphorus (1.10%), manganese minerals dominated by manganese carbonate, and manganese oxides are rare. Manganese carbonate minerals include manganese dolomite, rhodochrosite, and manganese calcite , which account for 67.20%. Among them, manganese dolomite is the main one, and rhodochrosite accounts for about 8%, and manganese calcite is rare. Manganese dolomite is mainly composed of granular and vein-like aggregates. The vein diameter is 0.085-0.1455mm, and the granular shape is mostly 0.0291-0.0485mm. The rhombohedral ore is spherical or ring-shaped, and contains quartz fine particles or carbonaceous and shale. The particle size is mostly in the range of 0.0485 to 0.194 mm. The gangue minerals are quartz, dolomite, calcite and the like. The harmful impurities are colloidal phosphate, which has the biological structure of mollusks, such as bryozoan, valvular worm, and is connected with quartz and manganese dolomite as vein aggregates, resembling opal, crack cleavage, and cleavage along the crack. It is replaced by calcite, with a particle size of 0.1455-0.0813 mm and a small amount of fine-grained apatite.
Multi-element and phase analysis of ore
The results of multi-element analysis of raw ore are shown in Table 1, and the results of phase analysis of manganese are shown in Table 2.
Table 1 Results of multi-element analysis of raw ore
Component
Content
Mn
10.88
P
1.09
TFe
0.80
SiO 2
17.20
Al 2 O 3
1.73
CaO
19.21
Component
Content
MgO
9.74
S
0.543
Cu
0.003
Pb
0.01
Zn
0.01
CO
0.002
Table 2 Results of phase analysis of ore manganese /%
Manganese phase
Manganese in carbonate
manganese dioxide
Manganese combined with iron
Total manganese
Content
10.82
0.42
0.02
11.26
Occupancy rate
96.06
3.73
0.18
100.0
Since both manganese minerals and gangue minerals are carbonates, their physicochemical properties are similar, and the cation radius is similar, they can be replaced one by one, thus forming a series of isomorphic minerals, which makes the range of manganese in manganese dolomite relatively large. It causes the diversity and complexity of manganese carbonate minerals and directly affects the mechanical beneficiation index.
Second, the study of mechanical beneficiation methods and process
At present, in the world, the mechanical beneficiation methods and processes for refractory manganese carbonate ore tend to be a combined process of several mineral processing methods. For example, the Pokrovsk manganese carbonate ore dressing plant in the former Soviet Union used a washing-magnetic separation-flotation combined process to increase the grade of manganese from 16.55% to 28.60%, and the recovery rate was 86.95%. In the former Soviet Union's Chatura concentrator, the washing-re-election-magnetic separation-flotation process was used to increase the manganese ore grade from 7.85% to 29.30%, and the recovery rate was about 85%. When the main mineral in the carbonate is rhodochrosite, a single flotation method is used for sorting. Because rhodochrosite is a good floatability in manganese-containing minerals, it is quite successful to select fatty acid anion collectors . For example, in Dajiangling Manganese Mine in Japan, 13.20% of ore containing manganese is treated by flotation process, and manganese concentrate containing 32.30% of manganese and 82.90% of recovery is obtained by using oleic acid as a collector (578 g/t). 96% manganese is rhodochrosite and manganese dolomite, which can be selected by flotation.
(1) Flotation of phosphorus removal to improve manganese ore grade
In view of the fact that most of the manganese-containing minerals and gangue minerals in the ore are carbonates, their physical and chemical properties are not much different. It is particularly noteworthy that the phosphate rock and carbonate minerals are in addition to density, conductivity and floatability. Similar and closely symbiotic with each other, also because some PO 4 3- in the phosphate rock is replaced by CO 3 2- in the carbonate, F - is replaced by OH - , resulting in crystal constant, surface electrical properties closer to carbonates Minerals, so that the phosphate rock and manganese-containing minerals are similar in floatability. It is difficult to achieve the purpose of enriching manganese and removing phosphorus by directly floating manganese with fatty acid collectors or dephosphorization by reverse flotation. For example, if oleic acid is used as a collector of manganese minerals and sodium silicate is used as an inhibitor, the flotation foam product contains 12.19% manganese and phosphorus content 1.2 under the conditions of fine ore fineness of 95%-74μm and pulp pH 8～9. %, manganese and phosphorus are not enriched.
The possibility of reverse flotation phosphorus removal by cationic collectors was investigated. Eighteen carbonamine 500g / t, caustic starch 800 g / t, sodium carbonate 1000 g / t, grinding fineness 74μm accounted for 90%, the mine will have a temperature of about 25 ° C, pH 8 ~ 9 conditions, after a rough selection, More than 33% of the phosphorus in the ore can be removed. That is, the content of manganese in the foam product is 5.5%, the occupancy rate is 11.37%, the content of phosphorus is 1.8%, and the occupation rate is 60.06%. In the products in the tank, the content of manganese is 12.70%, the occupancy rate is 88.63%, and the content of phosphorus is It is 0.82% and the occupancy rate is 39.40%. In order to remove this part of the phosphorus, several processes and different types of inhibitors were tested, but none of the manganese concentrates containing less than 0.2% phosphorus were obtained.
(2) Dry strong magnetic separation test
It is well known that manganese oxide or manganese oxides are weak magnetic minerals. Because of the large difference in the specific magnetic susceptibility of manganese-bearing minerals and gangue minerals and minerals containing harmful impurities, strong magnetic separation is one of the effective methods for the mine. The specific magnetization coefficients of several common manganese minerals and gangue minerals are shown in Table 3.
Table 3 Common susceptibility of several manganese minerals and gangue minerals
Mineral
Particle size / mm
Specific magnetic susceptibility / (cm 3 ·g -1 )
Rhodochrosite
Pyrolusite
Manganese ore
Hard manganese ore
Manganese-containing calcite
Calcite
dolomite
Shi Ying
apatite
-0.83
-0.83
-0.83
-0.83
-0.83
-0.13
-0.13
-0.13
-0.13
(135～140)×10 -6
27×10 -6
(28×81)×10 -6
(24~49)×10 -6
(66~94)×10 -6
0.3×10 -6
2×10 -6
(0.2~10)×10 -6
(9.39~819)×10 -6
According to the characteristics of the ore, the test compares the dry strong magnetic separation scheme with and without deliming, grading and non-grading, and determines the desliming-grading-magnetic separation flow diagram (see Figure 1), and obtains the selection of Table 4. Other indicators. Since the occupation rate of slime is 22.59%, the content of manganese and phosphorus are close to the original ore grade. Therefore, the strong magnetic separation of the slime increases the recovery rate of manganese by about 10%. Graded dry magnetic separation can remove about 67% of the phosphorus in the ore, that is, the content of manganese in the magnetic separation concentrate can be increased to 18.41%, and the phosphorus can be reduced to 0.31%, which meets the grade requirements of the Ministry of Minmetals. . If we want to increase the grade of manganese and reduce the phosphorus to below 0.2%, it is still a problem that is difficult to solve by this method.
Table 4 Desliming - Grading - Magnetic Separation Test Results /%
product name
Yield
Grade
Recovery rate
Mn
P
Mn
P
Concentrate
Tailings
Total
44.01
55.99
100.0
18.41
5.76
11.33
0.31
1.55
1.00
71.16
28.84
100.0
13.46
86.54
100.0
(3) Warm and strong selection test
The wet magnetic separator is suitable for processing fine-grained materials and is also an effective magnetic separation equipment for selecting manganese-containing minerals.
The test uses a ring magnetic separator to perform non-hierarchical magnetic separation. The manganese product grade of magnetic products has increased to 22%. Phosphorus is reduced by 0.3%, while manganese recovery is only 23% and tailings grade is above 6%. The three processes were compared using a splint type strong magnetic separator: (1) deliming (-25 μm) magnetic separation; (2) fractional magnetic separation; and (3) reverse flotation concentrate magnetic separation.
The original ore milled to -75μm accounted for 65%. After deliming, the coarse sand and the slime were separately subjected to wet strong magnetic separation to obtain a product containing 17.14% manganese, a recovery rate of 63.03%, and a phosphorus content of 0.41%. The process and selection indicators are shown in Figure 2 and Table 5.
Table 5 Wet strong magnetic separation test results /%
product name
Yield
Grade
Recovery rate
Mn
P
Mn
P
Concentrate
Tailings
Total
40.60
59.40
100.0
17.14
7.36
11.33
0.41
1.47
1.04
63.03
36.97
100.0
16.21
83.79
100.0
The graded wet magnetic separation obtained manganese concentrate with 17.71% manganese and 0.42% phosphorus, which was similar to the magnetic separation grade after de-mudging, and the recovery rate was 59.42%.
After reverse flotation dephosphorization, the products in the tank are subjected to strong magnetic separation and reprocessing, and manganese concentrate containing 17.35% manganese, 0.39% phosphorus and 57.2% recovery can be obtained.
After several test schemes, dry and warm magnetic separation are effective methods for treating the ore. However, to further reduce the phosphorus content of manganese concentrate and increase the manganese grade, single strong magnetic separation is not easy to solve.
Third, chemical methods to remove phosphorus, improve manganese ore grade
The manganese concentrate obtained by mechanical beneficiation has no change in the physicochemical properties and mineral composition of manganese-containing minerals, and is also a carbonate mineral. The content of manganese is about 18%. Phosphorus is dephosphorized ore and a small amount of very fine apatite. Its content is about 0.4%, which accounts for about 1/3 of the original ore. It is difficult to remove this part of phosphorus by a single mechanical beneficiation method. When dealing with this type of ore at home and abroad, chemical methods such as manganese selection, roasting-acid leaching or water immersion, sub-acid salt method, sulfur dioxide method, manganese sulfate-electrochemical method, and dithionite method are used. Nitric acid method, ion exchange method, bacterial leaching method, and the like.
Referring to the chemical treatment method of manganese carbonate ore type with high impurity at home and abroad, the magnetic roasting of the manganese ore is subjected to a neutral roasting-acid leaching test to further improve the manganese ore grade and reduce the phosphorus content.
(1) Neutral roasting test
According to the chemical nature of the mineral and the effect of acid leaching and dephosphorization, manganese carbonate is subjected to neutral calcination to convert manganese carbonate into manganese oxide without being dissolved by dilute acid. Moreover, the manganese carbonate mineral is decomposed during roasting, and CO 2 and other volatiles are discharged, so that the manganese content is further increased, the fuel consumption in the smelting process is reduced, and the smelting time is shortened.
Principle of roasting of manganese carbonate ore: Manganese carbonate is decomposed by heat, releasing carbon dioxide, crystal water and volatile matter, so that manganese carbonate becomes oxide and obtains manganese oxide. This change is more oxidized with increasing temperature, so that roasting The amount of manganese in the mine is also relatively reduced. The roasting oxidation process is:
The roasting test was carried out using a box type muffle furnace, and the conditions of the baking time and temperature were tested. When the temperature is 800 ° C and the time is 75 min, the manganese concentrate grade after roasting is increased to 26% to 28%, and the phosphorus content is also increased to 0.43% to 0.53%.
(2) Phosphorus removal test of dilute sulfuric acid
Since the calcination test itself is not a complete process, an acid leaching phosphorus removal test was carried out for this purpose. According to the chemical properties that manganese oxide is not easy to react with dilute sulfuric acid, and phosphorus is easily dissolved by dilute acid, a dilute sulfuric acid leaching phosphorus removal test is carried out. Principle of acid leaching and phosphorus removal:
Calcium phosphate (phosphorus phosphate) in dilute sulfuric acid solution, the formation of dihydrogen phosphate (can be used as fertilizer) is present in the solution. Its chemical reaction formula is:
Ca 3 (PO 4 ) 2 +2H 2 SO 4 +4H 2 O=Ca(H 2 PO 4 ) 2 +2(CaSO 4 ·2H 2 O)
Calcined manganese ore, calcium magnesium oxide is also partially dissolved in the acid solution. Due to incomplete calcination, a small amount of manganese carbonate remains in the manganese concentrate after calcination, and manganese in the manganese carbonate is easily dissolved by dilute sulfuric acid to become manganese sulfate, so in the process of acid leaching and dephosphorization, part of the loss is lost. manganese. The acid leaching standard is shown in Table 6. The acid immersion surface is mechanically stirred. When the sulfuric acid concentration is 6%, the leaching time is 60-90 min, and the solid-liquid ratio is 1:7 to 1:15, the manganese concentrate grade is increased to 30% to 33%, and the phosphorus is lowered. Below 0.2%, the purpose of phosphorus removal and manganese concentrate grade is finally achieved.
Table 6 Acid leaching test results /%
Roasting feed
Leaching weight / g
Manganese in leaching
Phosphorus in leaching
Manganese in leaching
Occupancy rate
Dry magnetic separation concentrate
Wet magnetic separation concentrate
46.0
48.0
32.94
30.18
0.193
0.192
82.31
83.40
Fourth, the conclusion
(1) The manganese grade in the ore, and the manganese-containing mineral is a series of undetermined manganese dolomite and other manganese carbonate minerals, and the harmful impurities have high phosphorus content, and exist as cemented amorphous colloidal phosphate ore to form ore. The nature is complex and diverse, making mechanical beneficiation difficult to handle.
(2) When the original ore mill reaches -74μm, accounting for 65%-85%, remove the -25μm slime, each particle is subjected to dry or wet strong magnetic separation, and the slime is subjected to wet strong magnetic separation to obtain low grade manganese. Concentrate.
(3) Treating mechanically selected manganese concentrates by roasting-dilute acid leaching chemical method is an effective way to remove phosphorus, so that the final manganese concentrate grade is increased to more than 30%, and the phosphorus content is reduced to less than 0.2%. The recovery rate is about 60%.
(4) Chemical treatment of difficult-to-select manganese-poor ore, there are no strict requirements for raw ore, various types of manganese-bearing ore can be used, and high-quality concentrate products with less impurities can be obtained, especially suitable for chemical, battery, military and Metallurgical manganese raw materials can also be used to recover their associated elements.
Cui Enjing Ren Jinju Ma Jing Li Jie
(Shaanxi Nonferrous Metal Holding Group Co., Ltd., Xi'an 710006, China)
references
[1] Northwest Institute of Nonferrous Metals, Shandong Province, Shaanxi Province, high phosphorus and low manganese refractory ore test report [R], 2000, 12.
[2] Northwest Institute of Nonferrous Metals, Shaanxi Shiquan vanadium- titanium magnetite ore dressing test research report [R], 2003, 8.
[3] Ding Ruru, Yu Xixian, Manganese Mine Development and Processing Technology [M], Changsha: Hunan Science and Technology Press, 1991, 527.