In the present study we show that sodium benzoate substantially improves the efficiency of Soap LDO collector in the flotation of phosphate minerals.&#xd;&#xa

Mihir DM

Prabhulingaiah Gowda

Vijay Kumar P

English

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    Sodium Benzoate as Promoter in the Soap Flotation of Phosphate Minerals   
                                                           
                                                   
1Mihir, DM. 2Vijay Kumar, P and 2Prabhulingaiah, G. 
1Department of Chemical Engineering, Satyabhama University, Chennai. 
            
2JPM Plc. Co, Eshidiya Mines, Jordan. 
Corresponding author; prabhu2626@yahoo.co.in , 00962796122148 
Abstract: 
In the present study we show that sodium benzoate substantially improves the efficiency of 
Soap LDO collector in the flotation of phosphate minerals. 
Key Words: Soap Flotation, Hydrotropes, Sodium Benzoate. 
Introduction 
Jordan is blessed with huge phosphate ore deposits covering an area about 125 square 
kilometers. Eshidiya mine is located in the southern part of Jordanian plateau. The phosphate 
ore deposition occurred in three layers marked as A1, A2 and A3. A1 layer with a thickness 
of 2.6 meters has an over burden of 14 meters followed by an inter burden of 2 meters below 
which A2 layer of thickness 1 meter is located. Below the A2 layer there is an interburden of 
0.3 meters followed by A3 layer of 1.7 meters. A1 ore analyses 40 to 50% Tri Calcium 
Phosphate [TCP]. The gangue minerals are clay, marl, detrital quartz. A2 ore analyses 73 to 
75% TCP. Where as A3 ore analyses 25 to 45% TCP with gangue minerals such as clay and 
high silica. Thus where as A2 ore is directly marketed A1 anA3 ores need to be beneficiated. 
A1 ore beneficiation involves scrubbing and de sliming by cyclones where as A3 ore is 
scrubbed, de slimed and then fed to a flotation circuit.  
 
Flow sheet for A3 ore 
 
Sized A3 ore of – 12.5 mm is scrubbed in a drum scrubber and the discharge of the scrubber 
is fed to a primary vibrating screen with an opening of 2 mm and the -2 mm fraction is fed to 
secondary vibrating screen with screen openings of 1.25 mm. The over flow of the primary 
screen in the size range of -12.5 mm to + 2 mm is discarded as waste product. The over flow 
of the secondary vibrating screen is stored and marketed as sub commercial product. The 
under size of the secondary screen that is – 1.25 mm size is fed to the first stage de sliming 
hydro cyclone and the over flow of – 53 micron size is fed to a thickener. The under flow of 
the first stage hydro cyclone is fed to a second stage de sliming cyclones and the over flow is 
also fed to the thickener. The under flow of the second stage cyclones is fed to the third stage 
cyclones. The third stage cyclones over flow is re circulated as the feed of the second stage 
cyclones and the under flow of the third stage cyclones is fed to a hydro sizer to separate +53 
microns to - 500 microns in the over flow of the hydro sizer and the under flow contains 
particles in the size range +500 microns to – 1.25 mm. The over flow of the hydro sizer is  
 
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dewatered. The fine and coarse fractions from the hydro sizer are separately conditioned and 
fed to separate flotation circuits. Tall oil and Light Diesel Oil mixture is used as collector 
after reacting with sodium hydroxide to concentrate phosphate minerals as froth product and 
sodium silicate is used to depress silica which reports as the tailing. The rougher froth is 
cleaned thrice. The final concentrates are collected in a common sump and are fed to a cluster 
of dewatering cyclones. The under flow of these cyclones is fed to a belt filter and the filter 
cake is the final product that analyses 74% TCP plus or minus 2%    
 
Plant capacity  
 
Both the A1 and A3 circuits are in two lines each that can take unto 160 tons per hour. The 
weight percent recovery in A1 circuit is around 50% and the weight percent recovery in the 
A3 circuit is approximately 30%. The TCP
 
recovery in A1 circuit is around 60% and in A3 
circuit is from 25% to 30% depending on the type of ore fed. The total average production of 
A1 and A3 concentrates per annum of last fours is + 12 00000 tons of which 300000 tons is 
from A3 circuit. 
 
R & D Efforts 
Process Engineers at Eshidiya Beneficiation Plant have been attempting to improve the 
process and one of the areas is introducing new reagents for improved grade without reducing 
the TCP recovery. Hydrotropes1 which are known reagents that enhance the solubility of non 
polar solutes in water were tried. So far urea2, linear alkyl benzene sulfonate3, Alfa olefin 
sulfonate3 were successfully tested and tri sodium citrate, sodium salicylate are being tested.  
Present Study 
In the present study sodium benzoate is tested at bench scale at doses 0.58 and 1.15 Kegs per 
ton of ore and compared with plant conditions that is tall oil at 0.97 Kg per ton of ore, light 
diesel oil at 1.16 Kg per ton of ore and sodium silicate 0.35 Kg per ton of ore. The bench 
scale tests were of kinetics studies where incremental floats were taken. The tests were 
conducted using Denver flotation cell of 2 liters. The results are presented in Table 1 which 
are also plotted as shown in figure 1. It is obvious from figure 1 that sodium benzoate 
improves the soap flotation performance at a dose of 0.58 Kg per ton of ore and a higher dose 
may not be useful. All reagents used in this study are of commercial grade that are being used 
in the Eshidiya plant except sodium benzoate which is of AR grade assaying 99.5%.   
 
 
 
 
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Closing Remarks 
As it can be seen from the figure 1 that improvement of flotation efficiency of soap LDO 
emulsions up on adding sodium benzoate is unequivocal. Phosphate Beneficiation plant of 
RSMML Udaipur is already using Alfa Olefin Sulfonate as promoter in the flotation process 
which reduced the consumption of soap drastically. We expect similar results with sodium 
benzoate also. 
Figure 1 
 
% Cum TCP Grade % Cum TCP Recovery % Cum TCP Grade % Cum TCP Recovery % Cum TCP Grade % Cum TCP Recovery
73.76 26.00 76.06 17.08 76.20 11.24
71.53 65.34 73.47 45.02 76.24 22.93
70.85 85.80 72.54 71.21 73.38 44.07
70.79 92.25 72.54 87.11 71.01 68.33
70.85 93.54 72.59 90.47 70.67 93.5
Expt 1, Plant condition Expt 2,  Na Benzoate 0.58 Kg/ton of ore Expt 3,  Na Benzoate 1.15Kg/ton of ore
0.00
10.00
20.00
30.00
40.00
50.00
60.00
70.00
80.00
90.00
100.00
70 71 72 73 74 75 76 77
% Cum. TCP Grade
%
 
Cu
m
.
 
TC
P 
Re
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Plant Condition
Expt 2-Na Benzoate 0.58
Expt 3-Na Benzoate 1.15
 
 
 
 
 
 
 
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Table 1 
Bench Scale Experimental Details
Experiment-1, Plant condition
Sample coll. in secWt. in gms Wt. % Cum. Wt. % % TCP % TCP Rec. % Cum. TCP Rec. % Cum. Grade 
15 sec 109.90 18.87 18.87 73.76 26.00 26.00 73.76
30 sec 174.90 30.03 48.89 70.13 39.34 65.33 71.53
45 sec 92.80 15.93 64.82 68.76 20.46 85.80 70.85
60 sec 28.70 4.93 69.75 70.00 6.44 92.24 70.79
75 sec 5.40 0.93 70.68 74.25 1.29 93.53 70.85
R Tail 170.80 29.32 100.00 11.80 6.46
Total 582.50 100.00 99.99
Calculated feed %TCP 53.53
Reagent Dosing:
Tall Oil:   0.97 Kg/ton of ore, Light diesel oil: 1.16 Kg/Ton of ore, Sodiun silicate: 0.35 Kg/ ton of ore
Conditioning Time:
Conditioning time with depressent one minute and with collector two minutes.
Feed slurry:  25% solids by weight
Experiment-2, with Sodium Benzoate
Sample coll. in secWt. in gms Wt. % Cum. Wt. % % TCP % TCP Rec. % Cum. TCP Rec. % Cum. Grade 
15 sec 72.70 12.45 12.45 76.06 17.08 17.08 76.06
30 sec 125.60 21.51 33.97 72.00 27.94 45.03 73.47
45 sec 119.40 20.45 54.42 71.00 26.19 71.22 72.54
60 sec 70.80 12.13 66.55 72.68 15.90 87.12 75.57
75 sec 14.90 2.55 69.10 73.16 3.37 90.48 72.59
R Tail 180.40 30.90 100.00 17.09 9.53
Total 583.80 100.00 100.01
Calculated feed %TCP 55.44
Reagent Dosing:
Tall Oil:  0.97 Kg/ton of ore, Light diesel oil: 1.16 Kg/ton of ore, Sodium silicate: 0.35Kg/ton of ore.
Sodium Benzoate: 0.58 Kg/ ton of ore.
Conditioning time:
Conditioning time with depressent one minute and with Collector two minutes.
Feed slurry  25% solids by weight
Experiment-3, with Sodium Benzoate
Sample coll. in secWt. in gms Wt. % Cum. Wt. % % TCP % TCP Rec. % Cum. TCP Rec. % Cum. Grade
15 sec 46.10 7.96 7.96 76.20 11.24 11.24 76.20
30 sec 47.90 8.27 16.23 76.28 11.69 22.93 76.24
45 sec 93.70 16.18 32.41 70.52 21.14 44.07 73.38
60 sec 113.00 19.51 51.93 67.11 24.26 68.34 71.01
75 sec 114.00 19.69 71.61 69.00 25.17 93.50 70.67
R Tail 164.40 28.39 100.00 12.34 6.49
Total 579.10 100.00 100.00
Calculated feed %TCP 53.97
Reagent Dosing:
Tall Oil:   0.97 Kg/ton of ore, Light diesel oil:  1.16 Kg/ton of ore, Sodium silicate: 0.35Kg/ton of ore.
Sodium Benzoate: 1.15 Kg/ ton of ore.
Conditioning time:
Conditioning time with depressent one minute and  with Collector two minutes.
Feed slurry:  25% solids by weight
 
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 Acknowledgement. 
We are thankful to the management of M/s JPM Plc. Co for permitting to take in plant 
training in their Eshidiya beneficiation plant. He is thankful to Mr. Ahmed Salameh, Mr. 
Yasser Dassin, Mr. Daksh Shukla, Mr. Gummadi Karun, Mr. John Britto, Mr. Krishna Kumar 
Godara. 
D M Mihir is thankful to Dr. Joshua Amarnath, Head of the Department of Chemical 
Engineering, Sathyabama University. The content in this paper is a part of the project work of 
DM Mihir submitted to Satyabhama University. 
 
References 
[1] Roy, BK and Moulik, SP, Effect of hydrotropes on solution behavior of amphiphiles, 
Current Science, 85(8), 25 October, 2003, P 1148-1155. 
[2] Sekhar, DMR., Srinivas, K., Prabhulingaiah, G. and Yasser Dassin, Urea as promoter in 
the soap flotation of phosphate ores, Trans. IIM Vol.62, issue 6, December 2009, p 555-557. 
[3] Sekhar, DMR, Srinivas, K., Prabhulingaiah, G., Dassin, Y. and Alftinah, A., Promoters 
for soap flotation of Phosphate minerals, Proceedings of the International Mineral Processing 
Congress 2010, P 2345 – 2349. 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
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Sodium Benzoate as Promoter in the Soap Flotation of Phosphate Minerals

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