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The nature of black medicine
The commonly used cresol black medicine in China is 15 #é»‘è¯ and 25 #黑è¯, they are black-green oily liquid, so it is called black medicine, but many similar species
S
/
Receipt, many similar collectors , such as ethyl sodium black drug (CH 3 CH 2 O) 2 P-SNa is a white powder, butammonium black is not black, but white or gray powder, they Although the color is not black, it is also known as black medicine.
The acid black medicine has a small solubility in water, and the ammonium black medicine or the sodium black medicine has a large solubility to water.
15 #黑è¯,25 #黑è¯å’Œ31 #é»‘è¯ Contains free cresol, so it has strong foaming properties. When using this kind of black medicine, you can use less or no foaming agent; cresol has very good skin. Strong corrosive, so phenolic black medicine should not be in contact with the skin, so as not to damage the flesh, especially not to hurt the eyes. When the flesh is exposed to cresol black medicine, it should be washed with plenty of water in time; the cresol is adjacent, inter-, and tri-synthesis The black body of the structure, which is synthesized from m-cresol, has the strongest harvesting ability, followed by p-cresol and o-cresol, but this is theoretically valuable and has no production. meaning, because pharmaceutical processing plant cresol black male drug germanium mixed cresol as raw materials synthesis.
During the synthesis process, the thiohydrogen formed by the reaction is partially dissolved in the black drug, and the black drug dissolved in hydrogen sulfide has a slight vulcanization effect on the oxidized mineral, and is favorable for vulcanization of the oxidized ore which is oxidized on the surface.
Black medicine also has the following three main chemical properties:
1. Oxidation into double black medicines Black medicine is more stable than xanthate. It is not as easy to decompose in acid pulp as yellow medicine, and it is also difficult to oxidize, but it can also be oxidized into double black medicine. For example, it can be black with phosphorus and black medicine. The drug is oxidized into a double black drug:
2(RO) 2 PSS - +I 2 —→(RO) 2 PSS—SSP(OR) 2 +2I -
Black medicine double black medicine
Therefore, when analyzing black medicine, the sulphur method can be applied as well as the analysis of xanthate. Double black medicine is also a good collector for sulfide ore.
Black powder in the presence of Cu 2+, Fe 3+, or pyrite, at Hui copper ore, partially oxidized black dual drug, see Figure 1 and Table 1 and Table 2.
Figure 1 is oxidized with 2.5 × 10 -4 moles / liter of Cu 2+ ions 5 × 10 -4 moles / liter, ethyl
Black medicine becomes the reaction speed of double black medicine (DDP) 2 [45]
○ pH=6 △ pH=8 × pH=10
Ethyl black medicine (DDP-) is oxidized to ethyl double black drug (DDP) in the presence of 100-200 mesh cuprite
2 (action time 10 minutes) Table 1
pH value
Copper ore weight (g)
DDP - (M)
Generate (DDP) 2 (M)
2.0
4.0
6.0
8.0
10.0
1
1
1
1
1
5×10 -4
5×10 -4
5×10 -4
5×10 -4
5×10 -4
1.1×10 -1
3.6×10 -5
3.1×10 -5
trace
trace
Ethyl black medicine (DDP - ) is oxidized to ethyl double black drug (DDP) 2 in the presence or absence of 100-200 mesh pyrite.
(action time 10 minutes) Table 2
pH value
Pyrite weight (g)
DDP - (M)
Fe +++ (M)
Generate (DDP) 2 (M)
2.0
3.0
2.0
3.0
4.0
6.0
8.0
0
0
2
2
2
2
2
5×10 -4
5×10 -4
5×10 -4
5×10 -4
5×10 -4
5×10 -4
5×10 -4
2.5×10 -4
2.5×10 -4
0
0
0
0
0
7×10 -6
no
5.3×10 -5
3.3×10 -5
<7×10 -6
<7×10 -6
no
It can be seen from Fig. 1 that Cu 2+ and Cu(OH) 2 can oxidize ethyl black medicine to ethyl double black medicine, and reach equilibrium within 10-15 minutes, time increases again, and the oxidation product is close to a fixed value; The oxidation is expressed by the reaction formula as follows:
1
Cu 2+ +2DDP - â†â†’ DDPCu (S) + —— (DDP) 2
2
1
Cu(OH) 2 +2DDP - +2H + â†â†’ DDPCu (S) + ——(DDP) 2 +2H 2 O
2
The Ph value is below 8, the black medicine is oxidized to double black medicine, and when the pH is 10, the ethyl black medicine is not oxidized. This may be because at high pH, ​​the H + ions are rare, and Cu 2+ and OH - acts. The generated Cu(OH) 2 is stable and more stable than ethyldithiophosphoric acid, so the oxidation reaction cannot be carried out, and the equilibrium cannot be said to the right.
It can be seen from Table 1 that when the copper ore is crushed to a certain particle size and has a large enough surface area, when the oxygen adsorbed on the surface of the chalcopyrite has a low pH value, part of the ethyl black drug can be oxidized to a double black drug, or even At pH = 10, a small amount of oxidation reaction also occurred.
From the experimental data in Table 2, it is seen that at low pH, no pyrite is present, and 2.5×10 -4 gram of ferric chloride is added, and the ethyl hydrazine is oxidized by Fe 3+ to ethyl bisphenol. The amount is not much; under the same conditions, without adding ferric chloride solution, and adding 2 grams of 100-200 mesh pyrite, the amount of ethyl black medicine is oxidized to ethyl double black medicine, about ten times, When the pH value is increased, the degree of oxidation of the black drug is reduced, so it is estimated that the ability of the oxygen-adsorbed ethyl black drug adsorbed on the surface of the pyrite is stronger than that of the barium iron ion.
2. Acidic black drug is weakly acidic, partially ionized in large solution
S S
RO / RO /
> P-SH â†â†’ > P-S - +H +
RO RO
The ionization constant is slightly different depending on the hydrocarbon group. For example, the ionization constants of ethyl, n-propyl, isopropyl and isobutyl black are correspondingly 2.4×10 -2 , 1.78×10 -2 , 1.5×10 - 2 , 1.00 × 10 -2 , it can be seen that the acidity of the black medicine is not strong.
3. Black drugs and some metal ions form insoluble salts action
Me n+ +n(RO) 2 PSSH —→ [(RO) 2 PSS] n Me↓+nH + n can be 1, 2 or 3, ie Me n+ represents certain monovalent, divalent or trivalent metal ions . Table 3 lists the solubility product constants of some insoluble metal salts of black medicines.
Solubility product constant of black metal salt (25 ° C) Table 3
Metal cation
n
[(C 2 H 5 O) 2 PSS] a Me
[(CH 3 CH 2 CH 2 CH 2 O) 2 PSS] a Me
[(CH 3 C 6 H 4 O) 2 PSS] a Me
Hg 2+
Ag +
Cu +
Bi 3+
Pb 2+
Sn 2+
Cd 2+
Ni 2+
Zn 2+
2
1
1
3
2
2
2
2
2
1.15×10 -32
1.3×10 -16
5.5×10 -17
7.5×10 -12
6.2×10 -12
1.5×10 -10
1.5×10 -10
1.7×10 -4
1.5×10 -2
-
0.47×10 -18
-
-
6.1×10 -16
-
3.8×10 -13
-
-
-
1.15×10 -19
-
-
1.8×10 -17
-
1.5×10 -12
-
-
Black medicine and metal ions can form insoluble salts, which is an important reason why black medicine can be used as a collector. Because the solubility of metal salts of black medicine is larger than that of corresponding metal salts, the arrest of black medicine The ability to receive is worse than that of xanthate, and the selectivity is better than that of xanthate.