Higher quality and Lower Price Carbon Steel/Stainless Steel Pipe Fittings Produced by Jimeng Group.We produce all kinds of Carbon Steel/Stainless Steel Cap,Socket,Cross,and Threaded High Presure Stainless/Carbon Steel Fittings.
Size:DN 10-DN 2000
Standard:ANSI,ASME,JIS,KS,GOST,DIN,UNI,EN,GB
Export Country:US.UK.SERBIA,RUSSIA,ITALY,IRAN,KOREA,JAPAN,SPAIN,CHILE,BRAZIL
SCH NO:5,10,20,30.40,60,80,120,140,160,STD,XS
Welding Method:Seam,Seamless,Half Seamless.
Radius Type:1.5D(Long),1.0D(Short)
Surface Finish:Nature Surface,Sand Blasting,Painting.
Material:SS 304/304L/316/316L/201/430,CS Q235/A234/Q195/A105/20#/16MN
Certificate:ISO-9001,KS,CE
Carbon Steel Cap, Carbon Steel Pipe Cap, Carbon Steel BE end Cap Hebei Jimeng Highstrength Flange-tubes Group Co.,Ltd. , https://www.jimengflange.com
In tungsten metallurgy, depending on the difference in molybdenum content in the raw materials and the specific process flow, molybdenum removal may be removed from the Na 2 W0 4 solution or the (NH 4 ) 2 W0 4 solution obtained by the purification transformation or the APT crystallization mother liquor (when When the content of aluminum and molybdenum in the raw material is small). At present, there are many molybdenum removal methods, but the most widely used in industry is based on the difference in affinity between tungsten and molybdenum for sulfur. First, under the condition of pH = 7.5~8 (for (NH 4 ) 2 W0 4 solution In other words, the pH is raised to pH = 10~11) S 2 is added to the solution, at this time, Mo0 4 2- and S 2- act:
Mo0 4 2- +4S 2- +4H 2 0 ==== Mo0 4 2- +80H -
Mo0 4 2- +nS 2- +nH 2 0 ==== Mo0 4-n S n 2- +2nOH -
While WO 4 2- is basically unchanged, the tungsten and molybdenum in the solution are present in the form of WO 4 2- , Mo0 4-n S n 2- + , respectively, and then separated by the difference in the properties of the two, and the industrial separation has been carried out. The process is:
A selective precipitation method for removing molybdenum, arsenic , tin , antimony from tungstate solution
The author firstly used the method of quantum chemical calculation to find out the difference between the microscopic properties of WO 4 2- and Mo0 4 2- . Then, using the molecular design method to find the orientation, it was found that the addition of M115 has a special affinity for Mo0 4 2- to form a precipitate. Entering the slag phase, while WO 4 2- does not react, remains in the solution, and after filtration, the tungsten-molybdenum achieves high-efficiency separation. At the same time, it was found that the oxyanions of the sulphur-containing elements such as SnO 3 2- , AsO 4 3- , and SbO 4 3- can be vulcanized to thioate ions, and thus can be simultaneously removed. The characteristics of this process are:
(1) Widely applicable, the above various impurities can be removed at one time from various tungstate solutions (including Na 2 W0 4 solution, (NH 4 ) 2 W0 4 solution, APT crystallization mother liquid, etc.).
(2) Except for the high molybdenum ratio, there is basically no limit to the molybdenum content in the original solution. The effect of molybdenum removal under industrial conditions is shown in Table 1.
The process has a 72% market share in the tungsten metallurgical technology market in China.
B ion exchange method
The affinity of the amine functional group on the strongly basic anion exchange resin to Mo0 4-n S n 2- is larger than that of WO 4 2- , so after the W0 4 2- , Mo0 4 2- mixture is added with S 2- conversion, Adsorption by gel-type or macroporous strong-base anion exchange resin, molybdenum is preferentially adsorbed in the resin phase, and the exchanged liquid is a tungsten solution containing little molybdenum. The resin adsorbed with Mo0 4-n S n 2- is desorbed by adding an oxidizing agent such as NaC10, H 2 0 2 or the like, and the reaction is:
Mo0 4-n S n 2- +4nNaC10+nH 2 0 ==== Mo0 4 2- +nS0 4 2- +2nH + +4nNaC1
Thus Mo0 4-n S n 2- becomes Mo0 4 2- desorption. Its main parameters and indicators are as follows:
a Preparation of feed liquid For (NH 4 ) 2 WO 4 feed liquid containing W0 3 : 100~250g / L, pH = 9~10, S 2- addition amount is 0.57~1.43g/L by MoS 4 2- , 40 ~ 90 ° C insulation 1 ~ 2.5h. Then keep at room temperature for 10~16h.
b Removal of molybdenum process When the molybdenum removal process is carried out on an ion exchange column: the adsorption flow rate is 2~8 cm/min until the molybdenum penetrates. The leaching tungsten solution contains NH 4 Cl 1~3 mol/L, pH=8.5~13, and the flow rate is 2~8cm/min. The desorbed molybdenum is a NaC10+NaCl solution (in which the NaCl concentration is 0.5-3.5 mol/L, the NaC10 concentration is 1-15 g/L of effective chlorine) or H 2 0 2 alkaline solution, pH=11~14.
The above oxidizing agent is used to oxidize Mo0 4-n S n 2- adsorbed on the resin to Mo 0 4 2- and SO 4 2- , thereby achieving the purpose of desorbing it.
In addition to the effects of Mo c when the solution MO / W0 3 = about 0.05%, after liquid exchange MO / W0 3 of about 0.005%.
d Recovery rate When MO/W0 3 =0.05% in the solution, the recovery rate of tungsten into the exchanged liquid is 85%~90%, and the eluent is 7%~8%. The recovery rate of molybdenum into desorbent is 87%~96%.
Since the exchange capacity is small when it is carried out on the ion exchange column, the oxidation process is slow at the same time as the desorption process. Therefore, Xiao Liansheng et al. have improved the adsorption process of molybdenum removal in a moving bed, and deoxidation and desorption in a fluidized bed, which greatly increases the exchange capacity and desorption rate, and the exchange capacity reaches Mo 70kg/m 3 resin. The loss of W0 3 is equivalent to lkg W0 3 /kg Mo.
C MoS 3 precipitation method a Basic principle The above vulcanized solution is neutralized to pH = 2.5~3 with HCl, then MOS 4 2- is precipitated into MoS 3 to separate from tungsten, and the reaction is:
MOS 4 2- +2HCl ==== MoS 3 +H 2 S+2C1 -
b Industrial practice The operation process, equipment and main control conditions and purification indicators of MoS 3 precipitation method in addition to molybdenum are summarized in Table 2.
D organic solvent extraction method for removing molybdenum
By extraction of molybdenum present in addition to many programs, wherein a quaternary ammonium salt extracted more mature, and its essence is added to the solution of S 2- MoO 4 2- + into MoS 4 2-, quaternary ammonium salt for The extractant extracts molybdenum and the reaction is:
2(R 3 CH 3 N) + Cl - +MoS 4 2 - ==== (R 3 CH 3 N) 2 + MoS 4 2- +2C1 -
The molybdenum-rich organic phase is back-extracted with sodium hypochlorite solution to oxidize MoS 4 2- to MoO 4 2- into the solution (similar to the desorption process of molybdenum removal by ion exchange), and the organic phase is returned to the extraction after stripping.
The material composition of Huang Weizhuang and other treatments is W0 3 75~85 g/L, Mo 0.03~0.17g/L, pH=8.2~8.4, after vulcanization, the organic phase is 1.2% N263 +20% TBP, and the rest is coal. oil, stripping agent is 0.3 mol / L NaOH and sodium hypochlorite solution 30g / L NaCl, using countercurrent extraction 6, two countercurrent extraction, the raffinate MO / W0 3 ≤0.O1%, the process W0 3 The loss is about 0.5% and the organic phase loss is about 3L/tW0 3 . 
Many users limit the content of molybdenum tungsten products in very demanding, our GB 10116-88 containing a predetermined amount of aluminum APT 0 should not exceed 20 × 10 -6, and therefore, in addition to the molybdenum metallurgical tungsten is an important step.
Table 1 Industrial production results of selective precipitation method for removing molybdenum
Type of liquid
Batch / (m 3 · batch -1 )
Material composition / (g·L -1 )
Clean liquid composition / (g · L -1 )
Ion exchange desorption peak
32.5
0.89
209
0.004
198
2×10 -5
Ammonium tungstate solution
14.5
0.55
226
0.012
212
6×10 -5
Ion exchange desorption peak
18.0
3.7
210
0.012
200
6×10 -5
Ion exchange desorption peak
10.0
0.04
220
0.001
210
5×10 -5
Ion exchange desorption peak
5.0
2.45
180
0.007
170
4×10 -5
Ion exchange desorption peak
7.0
0.7
210
0.006
200
3×10 -5
APT crystal mother liquor
40
0.12
30
0.005
29
(3) W0 3 recovery rate is high, Mo 15%~20% in the molybdenum slag, W0 3 2%~4%, equivalent to removing lkg Mo loss 0.2~0.3kgW0 3 , for lg/L Mo, 200g/L For the solution of W0 3 , the recovery rate is 99.8%~99.9%.
Table 2 Industrial practice of molybdenum removal by molybdenum trisulfide precipitation
Operation process and equipment
Main control condition
Purification index
Heat the Na 2 WO 4 solution to 70-80 ° C in an acid-resistant enamel reaction pot, add a theoretical amount of 125% to 150% NaHS, stir for 2 to 2.5 hours, and use 3 to 5 mol / L of HCl (if the molybdenum is removed directly Use the extraction method to neutralize to pH=2.5~3 with 2~3mol/LH 2 SO 4 ), boil for 1.5~2h, then filter with acid-resistant vacuum filter.
MoS 4 2- conversion stage: pH=7.2~7.3, temperature 70~75°C, time 2~2.5h, NaHS addition to ensure free S2 - concentration in solution 1.5~3g/L; MoS 3 precipitation Stage; pH=2.5~3, boiling time 1.5~2h
Except molybdenum rate 98%~99%, or Mo/W=0.01%~0.05% in solution after molybdenum removal; tungsten recovery rate is greater than 98%
The disadvantage of removing molybdenum by molybdenum sulfide precipitation method is that the molybdenum removal effect is not good, the recovery rate of tungsten is low, and the toxic gas H 2 S is released at the same time. Therefore, it is suitable for the Na 2 W0 4 solution containing lower molybdenum, so it has been eliminated in China. .