AU2017421972B2

AU2017421972B2 - Double-region flotation method for copper-cobalt sulfide ore in industrial production

Info

Publication number: AU2017421972B2
Application number: AU2017421972A
Authority: AU
Inventors: Jianping DUAN; Jingwen DUAN; Jianan LU; Yunqi PENG; Zhentang WANG; Hairui Yang; Enpu ZHANG; Qian Zhang
Original assignee: WANBAO MINING Ltd
Current assignee: WANBAO MINING Ltd
Priority date: 2017-07-06
Filing date: 2017-09-22
Publication date: 2020-06-25
Anticipated expiration: 2037-09-22
Also published as: CN107398353B; AU2017421972A1; CN107398353A; WO2019006889A1

Abstract

Disclosed is a double-region flotation method for a copper-cobalt sulfide ore in industrial production. The sorting process uses a flotation process flow, wherein the flotation process uses flotation in separate regions, which are divided into two regions, region 1 is mainly used for concentrate index control, and region 2 is used for recovery rate control. The method achieves a high-efficiency recovery for both copper and cobalt elements in the copper-cobalt sulfide ore in the scope of industrial production, and by using the double-region stepwise flotation method, effectively relieves the contradiction between the recovery rate and the concentrate grade in the field of ore dressing, improves the efficiency of quality control, greatly improves the optimization efficiency of the recovery rate and concentrate product index, and achieves the relatively separate control of the grade and the recovery rate.

Description

TWO-ZONED FLOTATION METHOD FOR COPPER-COBALT SULFIDE ORE IN INDUSTRIAL PRODUCTION FIELD OF THE INVENTION

[0001] This invention relates to the field of mineral processing engineering, and in particular to

a two-zoned flotation method for copper-cobalt sulfide ore in industrial production.

BACKGROUND OF THE INVENTION

[0002] There are few mature industrial applications in China for the beneficiation of

copper-cobalt sulfide ore. Recovery rate and concentrate grade are two interrelated and

contradictory indexes in the field of beneficiation. A problem lies in that it is not easy to relatively

separately control the concentrate grade and the recovery rate.

SUMMARY OF THE INVENTION

[0003] The technical problem to be solved by the present invention is to provide a tow-zoned

flotation method for copper-cobalt sulfide ore in industrial production, which allows the efficient

recovery of copper and cobalt from copper-cobalt sulfide ore in industrial production. A

two-zoned, stepwise flotation method effectively alleviates the contradiction between the recovery

rate and the concentrate grade in the field and increases the efficiency of quality control. Through

this method, the efficiency of optimizing the recovery rate and the concentrate grade is greatly

improved, and the relatively separate control of the concentrate grade and the recovery rate can be

achieved.

[0004] The technical solutions of the present application are as follows:

[0005] Atwo-zoned flotation method for copper-cobalt sulfide ore in industrial production,

characterized in that it comprises the following steps:

[0006] 1) step I: coarse grinding

[0007] pouring ore transported by a vehicle directly through a raw ore grid screen into an ore

storehouse, feeding the ore into a jaw crusher through a heavy plate feeder; transferring a coarse

grinding product to an intermediate ore pile through a belt conveyor;

[0008] 2) step II: intermediate ore pile stacking

[0009] providing an intermediate ore pile to act as an ore-supplying buffer for a separation

process to ensure ore supply during maintenance shutdown of grinding; this is due to an operating

system for coarse grinding being different from that for separation;

[0010] 3) step III: grinding

[0011] transporting ore from an intermediate ore pile to a semi-autogenous grinding mill by a

belt for grinding; transferring a sieved material to a hydrocyclone by a slurry pump for

classification after the sieved material enters a grinding sump; transferring sediment to a ball mill

for grinding; transferring a product of ball milling to a hydrocyclone by a slurry pump for

classification after the product of ball milling enters a grinding sump; sending an overflow product

for flotation, transferring sediment to a ball mill for grinding;

[0012] 4) step IV: flotation

[0013] adopting a zoned flotation process that is divided into two zones: zone I is mainly for

controlling a concentrate index, zone II is for controlling recovery rate, zone I and zone II

respectively comprises a mixing bucket, namely a 1# mixing bucket and a 2# mixing bucket, each

zone respectively produces a concentrate product, namely concentrate 1 and concentrate 2;

[0014] adopting a "two roughing, one scavenging, and three cleanings" process for a flotation

operation in zone I:

[0015] adding a reagent for zone I roughing Ito a1# mixing bucket; introducing an overflow

slurry of a hydrocyclone to a roughing I flotation cell after the overflow slurry enters a 1# mixing

bucket and is thoroughly mixed, the 1# mixing bucket is a starting point of zone 1; introducing

slurry of a roughing I operation to a roughing II operation; introducing slurry of a roughing II

operation to a scavenging operation; introducing froths of a roughing I operation and a roughing II

operation to a cleaning operation area in zone 1; allowing froth from a scavenging operation to return to a roughing II operation and slurry to go to a starting position of zone II, which is a 2# mixing bucket; cleaning zone I involves three cleaning processes: introducing froth of a cleaning I operation to a cleaning II operation, allowing slurry to return to a roughing I operation, introducing froth of a cleaning II operation to a cleaning III operation, adding no reagent in a cleaning III operation, allowing slurries from a cleaning II operation and a cleaning III operation to return to cleaning I and cleaning II separately and sequentially; froth of a cleaning III operation is concentrate I product.

[0016] The reagent for zone I roughing I is added to a 1#mixing bucket, and includes 600 g/t of

lime as a pH adjuster to keep the pH of slurry within 9.5 - 10.0, 150 g/t of sodium humate as an

inhibitor, 70 g/t of 2# oil as a frothing agent, and 60 g/t of butyl xanthate as a collector.

[0017] The reagent for zone I roughing II added includes 70 g/t of sodium humate as an

inhibitor, 24 g/t of 2# oil as a frothing agent, and 35 g/t of butyl xanthate as a collector.

[0018] Only 25 g/t of butyl xanthate as a collector is added in the scavenging operation of zone

I.

[0019] Only 40 g/t of sodium humate as an inhibitor is added in the cleaning I operation of

zone I.

[0020] Only 20 g/t of sodium humate as an inhibitor is added in the cleaning II operation of

zone I.

[0021] Adopting a "one roughing, two scavengings, and three cleanings" process for a flotation

operation in zone II:

[0022] adding a reagent for zone II roughing to a 2# mixing bucket; introducing slurry to a

roughing I flotation cell after the slurry is thoroughly mixed; introducing slurry of a roughing

operation to a scavenging I operation; introducing slurry to a zoneII cleaning operation area,

introducing slurry of a scavenging I operation to a scavenging II operation, allowing froth to

return to a roughing operation, adding no flotation reagent in a scavenging II operation,

introducing slurry of scavenging II to a tailings pond, transporting the slurry of scavenging II to a

tailings thickener by a slurry pump; a cleaning operation in zone II is divided into three cleaning

processes, introducing froth from cleaning I to cleaning II, allowing slurry to return to a roughing operation, introducing froth of a cleaning II operation to cleaning III; allowing slurries of a cleaning II operation and a cleaning III operation to return to cleaning I and cleaning II separately and sequentially; froth of cleaning III is concentrate II product.

[0023] The reagent for zone II roughing I includes butyl xanthate as a collector and sodium

humate as an inhibitor in an amount of 20 g/t and 30 g/t respectively.

[0024] Only 10 g/t of butyl xanthate as a collector is added to the scavenging I operation of

zone II.

[0025] In cleaning I and cleaning II of zone II, only sodium humate as an inhibitor is added in

an amount of 15 g/t and 10 g/t respectively.

[0026] The beneficial effects of the present invention are as follows:

[0027] This beneficiation method of copper-cobalt sulfide ore has a simple reagent system and

achieves a good separation effect through the optimization of both the process and the ratio of

reagents. The beneficiation process of this method is applied in a copper-cobalt mine. Flotation

zone I controls a product index, whereas flotation zone II mainly controls the recovery rate. By

adapting zoned-flotation and dividing the tasks, the contradiction between recovery rate and

concentrate grade in a beneficiation process can be alleviated, which separates the technical

solutions for these two goals and facilitates the control of indexes.

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The present invention has 3 drawings in total.

[0029] FIG. 1 is a diagram showing the devices for the two-zoned flotation method for

copper-cobalt sulfide ore according to the present invention.

[0030] FIG. 2 is a diagram showing the steps of the two-zoned flotation method for

copper-cobalt sulfide ore according to the present invention.

[0031] FIG. 3 is a flowchart showing the process of the two-zoned flotation method for

copper-cobalt sulfide ore according to the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

[0032] The present invention will be described in further detail below with reference to the

drawings and preferred embodiments.

[0033] Embodiment 1

[0034] The type of raw ore targeted is mainly copper-cobalt sulfide ore, of which the average

grade of copper is 1.5%, the average grade of cobalt is 0.5%. Its mineralogical characteristics are

as follows: copper minerals in the ore mainly include chalcopyrite, followed by porphyrite,

chalcocite, a very small amount of natural copper and copper blue, among others; cobalt mineral

is carrollite; sulfide minerals are mainly pyrite, among others; gangue minerals mainly include

dolomite, quartz, mica, among others; the ore contains a small amount of carbonaceous matter.

[0035] Grinding involves a SAB process of semi-autogenous grinding and ball milling.

[0036] The separation process involves flotation. The flotation process is a zoned flotation

process which takes place in two zones. Zone 1 is mainly for controlling a concentrate index,

whereas zone 2 is for controlling the recovery rate.

[0037] The main process is as follows:

[0038] 1. Coarse grinding

[0039] Raw ore density: 2.73 t/m 3 , loose factor: 1.5-1.7, moisture content of the ore: 2-5%.

[0040] The coarse crushing station is arranged in the open air. The ore transported by a vehicle

is directly poured through a raw ore grid screen into a storehouse.

[0041] The ore is then fed into a jaw crusher through a 1500x8000 mm heavy plate feeder.

[0042] The size of the crusher's feeding port is 850 x 1100 mm; the particle size of the

incoming feed is 0-750 mm; the maximum particle size of the product is 150 mm; the coarse

grinding product is transferred to an intermediate ore pile through a 1# belt conveyor.

[0043] 2. Intermediate ore pile

[0044] As the operating system for grinding is different from that for separation, to ensure ore

supply during maintenance shutdown of grinding, an intermediate ore pile is provided to act as

an ore-supplying buffer for the separation process.

Main Equipment at the Intermediate Ore Pile:

Name Main technical parameters

Belt conveyor B = 1000, Lh = 198.95 m, a = 8°

Heavy plate feeder 1200x 6000 (width x length)

Electric hoist Q=2t

Submerged pump 65ZJLA-B30

LPM7B-450 type air box pulse bag filter Air volume: 12,000 m 3/h, resistance: 470

1770 Pa, filtering area: 434 in2 , net filtering

area: 372 m 2

9-26NO11.2D type centrifugal fan Wind volume: 19,966 m 3/h, wind pressure:

3225 Pa, rotation speed: 960 r/min

D941W-IC type electric butterfly valve DN630

[0045] 3. Grinding

[0046] The particle size of a semi-autogenous grinding incoming ore is 250-0 mm, P80=

175mm; the required particle size of the discharged ore is -2mm > 80%, and grinding

concentration (average) is 75% - 80%. The discharge end is provided with a double-layer

cylindrical sieve (the size of an inner-layer sieve opening is 20 x 40mm, the size of an

outer-layer sieve opening is 6 x 15mm). The sieved material enters a grinding sump and is sent

to a hydrocyclone by a slurry pump for classification: the overflow product is sent for flotation;

the sediment enters a ball mill for grinding.

[0047] The particle size of the incoming ore for ball milling: P80 = 2mm; grinding

concentration (average): 75% -80%; cyclic loading: 300%; rotation speed: 13 r/min; rotation rate:

75%. The grinding product of the ball mill enters the grinding sump (shared with

semi-autogenous grinding) and is then pumped into a hydrocyclone by a slurry pump for

classification: the overflow product is sent for flotation; the sediment enters a ball mill for

grinding.

[0048] The specification of the group of hydrocyclones: D500x10; the amount of incoming feed slurry: 335.7m 3/h (taking fluctuation coefficient into account); the weight concentration of the overflow: 30%; overflow fineness: -0.074mm accounts for 80%.

Main Equipment in a Grinding Workshop

Name Main technical parameters

Belt conveyor B = 1000, Lh = 118.0 m, a =15

Wet-type semi-autogenous grinding mill D5.5x3.0 (EGL)

With a semi-autogenous grinding

low-pressure part

Overflow-type ball mill D3.8x6.6 m

With a ball mill low-pressure part

Slurry pump (cyclone feed) 250/200

Group of hydrocyclones 0500x6

Electric hoist Q = 2 t, H = 15 m

Pipe sampler (raw ore) DN600

Submerged pump 65 (exit)

Car crane Q = 50 t

Car crane Q = 20 t T35-11NO4 axial fan Wind volume: 3800 m 3/h, full pressure: 88

Pa, rotation speed: 1450 r/min

T35-11NO6.3 axial fan Wind volume: 10,472 m 3/h, full pressure:

101 Pa, rotation speed: 960 rpm

KF-72LW air-cooled cabinet air conditioner Cooling capacity: 7200 W

Electronic belt scale 0 - 200 t/h

Electromagnetic Flowmeter 0- 60 m 3/h; DN100

Electric regulating butterfly valve DN100

Ultrasonic level meter 0- 4m

Pressure transmitter with remote 0 - 0.12 MPa

transmission

Online particle size analyzer -0.074 mm accounts for 65%

Density meter 0-40%

[0049] 4. Flotation

[0050] Two operation zones, zone 1 and zone 2 are involved in flotation. Each of the two zones

comprises a mixing bucket, namely, a 1# mixing bucket and a 2# mixing bucket. Each of the two

zones produces a concentrate product, namely, concentrate I and concentrate II. The detailed

process is described below.

[0051] The flotation operation in zone 1 can be summarized as a "two roughing, one

scavenging, and three cleanings" process.

[0052] The overflow slurry from the hydrocyclone enters a 1# mixing bucket, which is the

starting point of zone 1.

[0053] In zone 1 roughing I, reagents are added to the 1# mixing bucket. The reagents include

600 g/t of lime as a pH adjuster to keep the pH of the slurry within 9.5 - 10.0, 150 g/t of sodium

humate as an inhibitor, 70 g/t of 2# oil as a frothing agent, and 60 g/t of butyl xanthate as a

collector. After the slurry is thoroughly stirred, it enters a roughing I flotation cell. The slurry of

the roughing I operation then enters a roughing II operation.

[0054] The reagents added in the roughing II operation are 70 g/t of sodium humate as an

[0055] The slurry of the roughing II operation goes to scavenging. The froths of the roughing I

operation and the roughing II operation go to a cleaning operation area in zone 1.

[0056] In the scavenging operation, only 25 g/t of butyl xanthate as a collector is added. The

froth of the scavenging operation returns to the roughing II operation, the slurry goes to the

starting position of zone 2, which is the 2# mixing bucket.

[0057] The cleaning operation in zone 1 is divided into three cleaning processes.

[0058] In a cleaning I operation, only 40 g/t of sodium humate as an inhibitor is added. The

froth of cleaning I goes to a cleaning II operation, the slurry returns to the roughing I operation.

[0059] Similarly, in cleaning II, only 20 g/t of sodium humate as an inhibitor is added. The froth of cleaning II goes to a cleaning III operation.

[0060] In the cleaning III operation, no reagent is added. The slurries of the cleaning II

operation and the cleaning III operation return to cleaning I and cleaning II separately and

sequentially. The froth of the cleaning III operation is concentrate I product.

[0061] The flotation operation in zone 2 can be summarized as a "one roughing, two

scavengings, and three cleanings" process.

[0062] In a zone 2 roughing operation, reagents are added to the 2# mixing bucket. The

reagents include 20g/t g/t of butyl xanthate as a collector and 30 g/t of sodium humate as an

inhibitor. After the slurry is thoroughly stirred, it enters a roughing I flotation cell. The slurry of

the roughing operation then goes to a scavenging I operation, the slurry goes to a zone 2 cleaning

operation area.

[0063] In the scavenging I operation, only 10 g/t of butyl xanthate as a collector is added. The

slurry from the scavenging I operation goes to a scavenging II operation, the froth returns to the

roughing operation. In the scavenging II operation, no floatation reagent is added. The slurry

from scavenging II goes to the tailings pond and is transported to a tailings thickener by a slurry

pump

[0064] The cleaning operation in zone 2 is divided into three cleaning processes.

[0065] The froth of a cleaning I operation goes to a cleaning II operation, the slurry returns to

the roughing operation. In cleaning I and cleaning II, only sodium humate as an inhibitor is

added in an amount of 15 g/t and 10 g/t respectively.

[0066] The froth from the cleaning II operation goes to cleaning III. The slurries of the cleaning

II operation and the cleaning III operation return to cleaning I and cleaning II separately and

sequentially.

[0067] The froth of cleaning III is concentrate II product.

Main Equipment in a Flotation Workshop

Name Main technical parameters

Flotation cell (flotation of sulfide ore) cI3.5x4.0 m

Flotation cell (flotation of oxide ore) cI4.0x4.5 m

Flotation machine XCF-30

Flotation machine KYF-30

Flotation machine XCF-8

Flotation machine KYF-8

Slurry pump (sulfide ore flotation concentrate) 80/65

Slurry pump (oxide ore flotation concentrate) 50/40

Slurry pump (tailings) 250/200

Pipe sampler (copper-cobalt sulfide concentrate) DN200

Pipe sampler (copper cobalt oxide concentrate) DN200

Pipe sampler (flotation tailings) DN350

Blower 450 m3 , 50 kPa

Submerged pump (accident pool) 65 (exit)

Submerged pump (in a tailings pit) 65 (exit)

Liquid level of a sulfide ore cleaning tailings pump pool 0- 1.5 m

Liquid level of a sulfide ore flotation concentrate pump pool 0- 1.5 m

Liquid level of an oxide ore flotation concentrate pump pool 0- 1.5 m

Liquid level of a flotation tailings pump pool 0 - 2.5 m

Blower outlet wind pressure 0 - 0.05 MPa

[0068] Production indexes are summarized in the table below.

Raw Ore The amount of ore selected Tons 86855

Grade of the ore selected

Wherein Cu % 1.50%

Co % 0.61%

The amount of metal in the

ore selected

Wherein Cu Tons 1306.44

Co Tons 528.56

Concentrate The amount of concentrate Tons 5635

Concentrate grade

Wherein Cu % 21.15%

Co % 7.43%

The amount of metal in

concentrate

Wherein Cu Tons 1191.86

Co Tons 418.79

Concentrate yield % 6.49%

Recovery rate

Wherein Cu % 91.23%

Co % 79.23%

Tailings The amount of tailings Tons 81220

Tailings grade

Wherein Cu % 0.141%

Co % 0.135%

The amount of metal in

tailings

Wherein Cu Tons 114.58

Co Tons 109.77

[0069] Judging from the production results, this method allows efficient separation of

copper-cobalt sulfide ore.

[0070] Finally, using this method, a copper-cobalt sulfide concentrate with a Cu grade of 23%

and a Co grade of 8% can be produced from a copper-cobalt sulfide raw ore with a Cu grade of

1.5% and a Co grade of 0.5%. The copper recovery rate is over 90%, and the cobalt recovery rate

is over 80%. In addition, through the optimization of the reagent system, the reformed process

allows mixed separation of copper-cobalt sulfide ores and copper-cobalt oxide ores; thus, oxide ore can also be treated.

[0071] Adapting the process described in Fig. 3, processing capacity reaches 3000 t/d; a copper-cobalt sulfide concentrate with a Cu grade of 23% and a Co grade of 8% can be produced

from a copper-cobalt sulfide raw ore with a Cu grade of 1.5% and a Co grade of 0.5%. The

copper recovery rate is over 90%, and the cobalt recovery rate is over 80%.

Claims

WHAT IS CLAIMED IS:

1. A two-zoned flotation method for copper-cobalt sulfide ore in industrial production, characterized

in that it comprises the following steps:

1) step I: coarse grinding

pouring ore transported by a vehicle directly through a raw ore grid screen into an ore storehouse,

feeding the ore into a jaw crusher through a heavy plate feeder; transferring a coarse grinding product

to an intermediate ore pile through a belt conveyor;

2) step II: intermediate ore pile stacking

providing an intermediate ore pile to act as an ore-supplying buffer for a separation process to

ensure ore supply during maintenance shutdown of grinding; this is due to an operating system for

coarse grinding being different from that for separation;

3) step III: grinding

transporting ore from an intermediate ore pile to a semi-autogenous grinding mill by a belt for

grinding; transferring a sieved material to a hydrocyclone by a slurry pump for classification after the

sieved material enters a grinding sump; transferring sediment to a ball mill for grinding; transferring

a product of ball milling to a hydrocyclone by a slurry pump for classification after the product of ball

milling enters a grinding sump; sending an overflow product for flotation, transferring sediment to a

ball mill for grinding;

4) step IV: flotation

adopting a zoned flotation process that is divided into two zones: zone I is mainly for controlling

a concentrate index, zone II is for controlling recovery rate, zone I and zoneII respectively comprises

a mixing bucket, namely a 1# mixing bucket and a 2# mixing bucket, each zone respectively produces

a concentrate product, namely concentrate 1 and concentrate 2;

adopting a "two roughing, one scavenging, and three cleanings" process for a flotation operation

in zone I: adding a reagent for zone I roughing I to a 1# mixing bucket; introducing an overflow slurry of a hydrocyclone to a roughing I flotation cell after the overflow slurry enters a 1# mixing bucket and is thoroughly mixed, the 1# mixing bucket is a starting point of zone 1; introducing slurry of a roughing I operation to a roughing II operation; introducing slurry of a roughing II operation to a scavenging operation; introducing froths of a roughing I operation and a roughing II operation to a cleaning operation area in zone 1; allowing froth from a scavenging operation to return to a roughing

II operation and slurry to go to a starting position of zone II, which is a 2# mixing bucket; cleaning

zone I involves three cleaning processes: introducing froth of a cleaning I operation to a cleaning II

operation, allowing slurry to return to a roughing I operation, introducing froth of a cleaning II

operation to a cleaning III operation, adding no reagent in a cleaning III operation, allowing slurries

from a cleaning II operation and a cleaning III operation to return to cleaning I and cleaning II

separately and sequentially; froth of a cleaning III operation is concentrate I product;

adopting a "one roughing, two scavengings, and three cleanings" process for a flotation operation

in zone II:

adding a reagent for zone II roughing to a 2# mixing bucket; introducing slurry to a roughing I

flotation cell after the slurry is thoroughly mixed; introducing slurry of a roughing operation to a

scavenging I operation; introducing slurry to a zone II cleaning operation area, introducing slurry of

a scavenging I operation to a scavenging II operation, allowing froth to return to a roughing operation,

adding no flotation reagent in a scavenging II operation, introducing slurry of scavenging II to a

tailings pond, transporting the slurry of scavenging II to a tailings thickener by a slurry pump; a

cleaning operation in zone II is divided into three cleaning processes, introducing froth from cleaning

I to cleaning II, allowing slurry to return to a roughing operation, introducing froth of a cleaning II

operation to cleaning III; allowing slurries of a cleaning II operation and a cleaning III operation to

return to cleaning I and cleaning II separately and sequentially; froth of cleaning III is concentrate II

product.

2. The method according to claim 1, characterized in that the reagent for zone I roughing I is

added to a 1#mixing bucket, and includes 600 g/t of lime as a pH adjuster to keep the pH of slurry

within 9.5 - 10.0, 150 g/t of sodium humate as an inhibitor, 70 g/t of 2# oil as a frothing agent, and 60

g/t of butyl xanthate as a collector.

3. The method according to claim 1, characterized in that the reagent for zone I roughing II added

includes 70 g/t of sodium humate as an inhibitor, 24 g/t of 2# oil as a frothing agent, and 35 g/t of

butyl xanthate as a collector.

4. The method according to claim 1, characterized in that only 25 g/t of butyl xanthate as a

collector is added in the scavenging operation of zone I.

5. The method according to claim 1, characterized in that only 40 g/t of sodium humate as an

inhibitor is added in the cleaning I operation of zone I.

6. The method according to claim 1, characterized in that only 20 g/t of sodium humate as an

inhibitor is added in the cleaning II operation of zone I.

7. The method according to claim 1, characterized in that the reagent for zone II roughing I

includes butyl xanthate as a collector and sodium humate as an inhibitor in an amount of 20 g/t and

30 g/t respectively.

8. The method according to claim 1, characterized in that only 10 g/t of butyl xanthate as a

collector is added to the scavenging I operation of zone II.

9. The method as claimed in claim 1, characterized in that in cleaning I and cleaning II of zone

II, only sodium humate as an inhibitor is added in an amount of 15 g/t and 10 g/t respectively.