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Application of ammonium chloride in the selection of arsenic, gold and silver lead-zinc ore
Guo Yueqin Wan Hongmin Yuan Lianxiao
Northwest Institute of Nonferrous Metals
Pick  To a high arsenic-containing lead zinc ore using conventional lead, zinc flotation scheme, lead, arsenic excessive levels of zinc concentrate. The client requested: using the flotation method to produce lead and zinc concentrates of the grade, reducing the arsenic content in lead and zinc concentrates, and increasing the recovery rate of gold and silver in lead concentrates as much as possible. In order to solve the problem of excessive arsenic in lead and zinc concentrates, ammonium chloride was added in the lead and zinc coarse and selective operations, which successfully reduced the content of arsenic in lead and zinc concentrates and made lead and zinc concentrates. The quality is qualified, and this result is applied to production and has achieved good results.
Keywords lead concentrate, zinc concentrate, arsenic content, ammonium chloride
Luonan a mineral ore is a plant selected arsenic, gold, silver, lead, zinc and other metals more refractory sulfide ore. The high content of harmful elements in the ore is high, which makes the arsenic content in the beneficiation selection (especially lead concentrate) exceed the standard, which seriously affects the economic benefits of the plant. To this end, the arsenic removal test of lead and zinc concentrates in the ore of the plant was carried out, and it was found that ammonium salts (such as ammonium chloride) have a good inhibitory effect on arsenic in the ore, and the results were applied to beneficiation production. A good result.
1 ore properties
Metal ore minerals are: pyrite, galena, sphalerite, arsenopyrite, silver, gold, copper, silver tetrahedrite ore; followed chalcopyrite, limonite. The gangue mineral is mainly quartz , followed by calcite , feldspar and chlorite.
The main element analysis results of the ore are shown in Table 1.
Table 1 Analysis results of main elements of ore
element
Pb
Zn
Au(g/t)
Ag(g/t)
Cu
Sb
As
content(%)
4.80
2.40
3.94
85.0
0.12
0.133
0.53
Main mineral content: (visual average): pyrite: 36.4%, galena: 6.5%, sphalerite: 2.9%, quartz: 45.0%, calcite: 9.0%, others: 0.2%.
The poisonous sand is the main mineral of the harmful element arsenic: granular and fragmented in the ore, followed by the self-formed crystal in the pyrite and sphalerite; the poisonous sand fissure is filled with galena fine veins.
Gold is mainly found in silver-gold ore independent minerals, and silver is mainly found in silver-bismuth copper ore. The silver-gold deposit is distributed along the pyrite fractures, or in the galena in the pyrite fissures, or in the pyrite, and the silver-bismuth copper ore is encased in the galena.
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2 dressing test
This paper focuses on the problem of excessive arsenic content in lead and zinc concentrates in the field, and finds effective inhibitors for inhibiting arsenic minerals (acacia), so that the quality of lead and zinc concentrates is qualified.
2.1 lead flotation test
Lead rough selection test: After the original ore grinding to -200 mesh accounted for 80%, the conventional conditions were tested to obtain the following pharmaceutical system: lead selection: inhibitor: lime + zinc sulfate: 3000 + 750 (g / t), collector : B Sulfur nitrogen + butyl ammonium black drug: 20+10 (g / t), foaming: 2 #æ²¹: 8g / t lead, in order to make lead concentrate qualified, first of all impurities arsenic does not exceed the standard; second consider gold, silver As far as possible, concentrate on lead concentrate, the process used is shown in Figure 1, and the list of indicators is selected 2.
Figure 1 lead rough selection test process
Table 2 lead rough selection experiment results
product name
Yield(%)
Grade (%)
Recovery rate(%)
Pb
Zn
As
Pb
Zn
As
Lead concentrate
9.00
52.00
2.18
0.87
92.46
7.89
15.21
Tailings
91.00
0.42
2.52
0.49
7.54
92.11
84.79
Raw ore
100.00
5.06
2.49
0.52
100.00
100.00
100.00
It can be seen from Table 2 that the lead is selected from conventional chemicals, and the arsenic content in lead concentrate is 0.87%. Therefore, we should consider adding inhibitors to lead selection to suppress arsenic minerals, so that the final lead concentrate contains no arsenic.
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2.1.1 Lead-selected arsenic mineral inhibitors
Arsenic minerals inhibitors lime, sodium cyanide, potassium permanganate, sodium hypochlorite, ammonium chloride, etc., found in the case of the conventional agent system unchanged, suppressing the use of lime and lead concentrate with ammonium chloride Medium arsenic, the effect is better, flow chart 2:
Note: Pharmacy dosage unit: g/t
Figure 2 Lead selected arsenic mineral inhibitors to explore the test process
When selecting, in the selected I, the amount of ammonium chloride is 0, 150, 250g / t, in the selected II, the amount of ammonium chloride is 0, 75, 125g / t, after the lead concentrate and lead Mineral testing and analysis, the content of arsenic in lead concentrate is 0.52~0.63%, and the content in lead ore is 0.82~1.73%. When the mine returns, it will affect the quality of the final product; and lead is added and not chlorinated. Ammonium and arsenic are highly enriched in lead ore. Therefore, it is decided to add ammonium chloride to suppress arsenic when the lead is coarsely selected.
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2.1.2 Lead crude ammonium chloride dosage test
The conventional pharmaceutical system remains unchanged. On the basis of the lead selection test, the lead is roughly selected by adding ammonium chloride while adding lime. The dosages are: 250, 500, 750, 1000 g/t, which are known from the analysis of crude concentrate. With the increase of the amount of ammonium chloride, the arsenic content in the lead concentrate is 0.93%, 0.80%, 0.48%, 0.47%, so it is better to select 750g/t for the crude ammonium chloride.
2.2 zinc flotation test
Lead-type tailings were tested for conventional zinc dosage, and the following pharmaceutical systems were obtained: lime 500g/t, copper sulfate 200g/t, butyl xanthate 30g/t, 2 # oil 23g/t, followed by zinc selection Ammonium chloride dosage test. Selected 1, lime 500g / t, ammonium chloride 150g / t; selected 2: lime 200g / t, ammonium chloride 100g / t. It can be seen from the results that the high content of arsenic in the zinc ore will affect the closed zinc concentrate, so that the arsenic content of the impurities in the zinc concentrate exceeds the standard. Therefore, ammonium chloride should be added to the rough selection and selection. The test determined that zinc was coarsely selected and ammonium chloride was added at 250 g/t.
2.3 closed circuit process test
On the basis of the conditional test, the closed process test was carried out by determining the better process conditions. Lead flotation: one rough selection, three selections, one sweep; zinc flotation: one rough selection, two second selection, one sweep. The process is shown in Figure 3, and the test results are listed in Table 3.
Table 3 closed circuit test results
product name
Yield
(%)
grade(%)
Recovery rate(%)
Pb
Zn
Au(g/t)
Ag(g/t)
As
Pb
Zn
Au
Ag
Lead concentrate
6.78
65.19
1.57
29.42
964
0.37
94.31
4.33
49.22
75.26
Zinc concentrate
4.15
0.63
52.85
8.60
195
0.20
0.56
89.16
8.81
9.18
Tailings
89.07
0.27
0.18
1.91
15.4
0.53
5.13
6.51
40.97
15.56
Raw ore
100.00
4.70
2.47
4.37
87.12
0.51
100.00
100.00
100.00
100.00
It can be seen from Table 3 that the arsenic content in lead and zinc concentrates does not exceed the standard, and gold and silver are mainly concentrated in lead concentrate.
3 conclusions
(1) In the formulation of the pharmaceutical system, the study focused on the impurity arsenic in lead and zinc concentrates that did not exceed the standard, and at the same time allowed gold and silver to be concentrated in lead concentrates.
(2) Lime can inhibit arsenopyrite, but the effect is different for different sources of arsenopyrite. Lime and ammonium salts (ammonium chloride or ammonium nitrate) are added at the same time, and the arsenopyrite is added by lime and ammonium chloride. Lost the ability to float.
(3) The amount of ammonium salt used is small, which has little effect on the grade of lead and zinc concentrate. The quality of lead and zinc concentrate is qualified to meet the production requirements.
references
"Flotation Theory and Technology" Hu Xigeng, Huang Hewei, Mao Yifan, etc. edited by Zhongnan University of Technology Press, September 1991, first edition P402~403
About the Author:
Guo Yueqin, female, 38 years old, senior engineer, No. 25, Xiying Road, Xi'an, Tel 029-7785292 5533878 (home) 5529945 (office)