DESCRIPTION:
Trial study was conducted for co-processing of red mud non Hazardous waste in kiln with a Clinkerisation capacity of 4500 MTD from 05th Dec to 09th December 2013.
The chemical characteristics of laterite envisaged to be used up to 2 to 3 % are as under

Chemical Characteristics of Laterite:

Oxides Fe2O3 Al2O3 SiO2 CaO MgO
% 38.48 21.43 26.03 0.91 0.56

The chemical characteristics of Red Mud available to be used.

Chemical Characteristics of Red Mud:

Oxides Fe2O3 Al2O3 SiO2 CaO TiO2
% 40.4 16.46 8.34 2.46 14.84

Brief Note on of Cement Manufacturing Process at Dalla Cement Factory:
Dalla cement factory is having two clinkerisation unit known as K4 and K5.

K4 1500 TPD Plant:
K4 Plant is an old plant having capacity of 1500 TPD commissioned in March 2008 equipped with Suspension Preheater Kiln and for raw Material grinding a combination of Roller press with ball Mill along with coal mill for fine coal Grinding.

K5 4500 TPD Plant:
K5 Plant is new plant having capacity of 4500 TPD commissioned in March 2008 equipped with state of art Polytrack cooler and for raw Material and coal grinding Polysius Vertical Roller Mills.

Full fledged quality control laboratory is maintained with on line and offline x-ray analyzer.

Both the plants are equipped with latest state of art technology Bag house, ESP and Bag filters for pollution control from the stack and cold fog system at lime stone crusher and coal wagon tippler to control fugitive dust.

Use of Industrial Waste as alternate Raw Material
Cement kilns traditionally uses laterite/iron ore to fulfill the requirement of iron oxide in raw mix. Adequate percentage of iron oxide present in red mud provides potential to use in cement raw mix for manufacturing of cement clinker. This leads to conservation of mineral like laterite / iron ore and utilization of industrial waste causing concern for the environmentalist. In other words, use of alternate raw material also offers conservation of traditional raw material.

Present Study
Trial study was conducted for co-processing of red mud in K-5 kiln with a clinker capacity of 4500 TPD during 05th December to 09th December 2013. Kiln process parameters, stack emissions and product quality parameters were observed closely for the 5 days trial period (one day without using red mud, three days using the red mud during trial run, one day after trial run without using red mud).
Red mud was fed along with limestone for Raw Meal grinding and storing into raw meal silo from where fed in preheater for cinkerisation. A feed rate of red mud was kept approximately 2.0% i.e. 150 TPD was targeted. However, the exact feed rate has been monitored on hourly basis and was recorded. Presently DCF is using approximately 1.5 to 2.0% i.e. 100 to 150 TPD of Additive; however this requirement may vary up to 4.0% with change in iron oxide in limestone and change in quality of Red Mud. In this study, emission of various pollutants such as SO2, NOx, HCl, HF, Hydrocarbons, CO, TOC, PAH, VOC, Dioxins & Furans etc. were monitored during co-processing of waste, pre & post co-processing.

Methodology of Trial Study:
Table 1: SCHEDULE OF TRIAL RUN WITH RAW MIX
Particulars Duration Raw Mix
Pre trial study 1st day
(05/12/2013) Lime stone with Laterite
Trial
co-processing with waste 2nd day
(06/12/2013) Lime stone with Red Mud
3rd day
(07/12/2013)
4th day
(08/12/2013)
Post trial study 5th day
(09/12/2013) Lime stone with Laterite

Table-2: PROCESS PARAMETERS OBSERVED DURING TRIAL STUDY
Sr.
No Parameter Pre Trial Run Trial Run with Solid Waste Post Trial Run
05.12.2013 06.12.2013 to 08.12-2013 09.12.2013
Min Max Avg. Min Max Avg. Min Max Avg.
1 Kiln speed, rpm 3.25 4.30 4.09 4.10 4.33 4.31 3.62 4.30 4.24
2 Kiln Torque, Amp 516 720 640 530 828 686 582 650 640
3 Kiln feed, TPH 280 336 311 305 331 321 303 325 320
4 BZ Temp °c 1180 1263 1240 1202 1306 1276 1179 1248 1234
5 Secondary Air Temp °c 997 1110 1052 1012 1120 1070 1007 1098 1062
6 Tertiary Air Temp °c 902 998 945 915 1025 958 904 1022 962
7 O2 % Kiln string 2.5 5.0 4.5 2.8 5.2 4.4 3.0 4.9 4.4
8 CO PPM kiln string 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Table-3: Quality Test Parameter of Clinker during trial run of Red Mud:

Table-4 Quality Test Parameter of Cement during trial run of Red Mud:

During the study period, consistency in process and quality parameters were maintained as represented in table no. 2, 3 and 4 .It is also analyzed that when additive is changed from laterite to Red Mud, there has been no change in % of various oxide in clinker along with various ratio like LSF (Lime saturation Factor), SM (Silica modulus) and AM (Alumina Modulus). Percentage of various phases like C3S, C2S, C3A and C4AF is also more or less similar in all the cases. Liquid content is also same as when used laterite.

When clinker is ground along with 30 % fly ash and 3 % Gypsum, We have not found any change in quality of cement before and after use of Red Mud. There has been similar strength after one day, 3 Days, 7 days and 28 days.

24-Hourly Sampling Frequency and Parameters Monitored:

Parameter like SO2, HCL, CO, Nox, TOC HF, Particulate matter, HC, VOC, PAH, Metals, Dioxins & Furans, Cyanides have been monitored and analyzed. The frequency of the parameter was four samples per day during trial study of Red Mud.

Table- 5: Summary of Average Level of Emissions During Trial Study of Red Mud
S. N. Parameter UOM Pre Trial Trial with Red Mud Post Trial
Average Range Average Range Average Range
1 Particulate Matter mg/Nm3 32.5 30.7-35.1 30.1 26.5-33.2 29.0 27.6-30.0
2 Sulphur dioxide mg/Nm3 6.7 6.2-7.1 6.0 5.3-6.5 5.7 5.3-6.0
3 Oxides of Nitrogen (NOx) mg/Nm3 853 798-882 830 814-854 820 786-848
4 Hydrocarbons mg/Nm3 121 112-130 112 97-126 111 109-112
5 Carbon monoxide mg/Nm3 56.6 48.9-60.7 48.4 36.8-56.5 42.0 35.6-45.6
6 Hydrogen Chloride (HCl) mg/Nm3 11.6 10.1-12.5 11.3 10.5-12.0 11.0 10.5-11.5
7 Hydrogen Fluoride (HF) mg/Nm3 1.8 1.5-2.1 1.5 1.2-2.0 1.7 1.2-2.2
8 TOC mg/Nm3 5.2 5.2 4.5 4.2-4.8 4.6 4.6
9 PAH µg/Nm3 0.71 0.70-0.72 0.5 0.4-0.7 0.7 0.5-0.8
10 VOC µg/Nm3 4.4 4.2-4.5 4.3 4.0-4.5 4.3 4.1-4.5
11 Cyanide mg/Nm3 <0.02 <0.02 <0.02 <0.02 <0.02 <0.02
12 Mercury mg/Nm3 0.0168 0.0168 0.0140 0.013-0.014 0.0151 0.0151
13 Cadmium + Thallium (Cd + Tl) mg/Nm3 0.014 0.014 0.010 0.008-0.012 0.016 0.016
14 Total Metals mg/Nm3 0.265 0.265 0.239 0.232-0.248 0.262 0.262
15 Total Dioxins and Furans mg/Nm3 0.0346 0.0346 0.0323 0.031-0.033 0.0354 0.0354

Table-6: Heavy Metals in Clinker:

Sr. No. Parameter UOM 05.12.2013 06.12.2013 07.12.2013 08.12.2013 09.12.2013
RESULTS
1 Antimony as Sb mg/kg 5.6 6.5 7.2 8.0 7.5
2 Arsenic as As mg/kg 0.56 0.45 0.53 0.47 0.39
3 Cadmium as Cd mg/kg <0.1 <0.1 <0.1 <0.1 <0.1
4 Chromium as Cr mg/kg 17.8 19.9 15.3 18.6 13.6
5 Cobalt as Co mg/kg <0.1 <0.1 <0.1 <0.1 <0.1
6 Copper as Cu mg/kg 46.5 53.2 59.0 52.6 54.1
7 Lead as Pb mg/kg 23.2 25.0 21.5 24.0 26.5
8 Manganese as Mn mg/kg 254.98 255.48 289.06 288.89 261.44
9 Mercury as Hg mg/kg 0.13 0.20 0.15 0.17 0.18
10 Selenium as Se mg/kg 0.12 0.10 0.11 0.08 0.10
11 Thallium as Tl mg/kg 2.0 2.2 1.7 4.1 2.5
12 Tin as Sn mg/kg <0.1 <0.1 <0.1 <0.1 <0.1
13 Vanadium as V mg/kg 7.2 6.5 7.5 7.2 6.7
14 Zinc as Zn mg/kg 63.5 70.5 63.6 68.5 65.5

Table-7: Clinker – TCLP Analysis

Sr. No. Parameters UOM Pre Trial During Trial Post Trial
1 Antimony as Sb mg/kg <0.01 <0.01 <0.01
2 Arsenic as As mg/kg <0.01 <0.01 <0.01
3 Cadmium as Cd mg/kg <0.01 <0.01 <0.01
4 Chromium as Cr mg/kg <0.01 <0.01 <0.01
5 Cobalt as Co mg/kg <0.01 <0.01 <0.01
6 Copper as Cu mg/kg <0.01 <0.01 0.04
7 Iron as Fe mg/kg <0.01 <0.01 0.11
8 Lead as Pb mg/kg <0.01 <0.01 <0.01
9 Manganese as Mn mg/kg 0.02 0.03 0.02
10 Mercury as Hg mg/kg <0.001 <0.001 <0.001
11 Nickel as Ni mg/kg <0.01 <0.01 0.02
12 Selenium as Se mg/kg <0.01 <0.01 <0.01
13 Thallium as Tl mg/kg <0.01 <0.01 <0.01
14 Tin as Sn mg/kg <0.01 <0.01 <0.01
15 Vanadium as V mg/kg <0.01 <0.01 <0.01
16 Zinc as Zn mg/kg 0.01 0.01 0.01

Test Method: USEPA SW-846, Method 1311

It is evident from the above table no. 5, 6 and 7 that:
• The particulate matter emissions were always less than 50 mg/Nm3, maximum observed was 30.1 mg/Nm3during trial co-processing of red mud;
• Sulphur Dioxide emissions during trial co-processing with red mud were observed to be ranging between 5.3-6.5 mg/Nm3;
• Oxides of Nitrogen emissions, which are much dependent on the temperature, were ranging between 814 to 854 mg/Nm3 during co-processing;
• HCL and HF emissions values were found to be 10.5 – 12.0 mg/Nm3and 1.2 – 2.0 mg/Nm3respectively during co-processing;
• Volatile organics were generated between 4.0 – 4.5 µg/Nm3 during trial co-processing of red mud;
• Polynuclear Aromatic Hydrocarbon emissions were observed in the range of 0.4 to 0.7 µg/Nm3 during trial co-processing with red mud;
• Dioxins & Furans were found to be 0.0346 mg/Nm3 during pre trial period, 0.0316 – 0.0332 mg/Nm3during trial co-processing with red mud and 0.0354 mg/Nm3during post trial period;
• The total heavy metals and mercury emissions values are 0.236 – 0.243 mg/Nm3and 0.0156 – 0.0183 mg/Nm3during co-processing with red mud;
• Total organic carbon was 4.2 – 4.8 mg/Nm3during co-processing with red mud;
• Ambient air quality was found to be normal representing the industrial activities.

Claims:

It is evident from the experience of handling the limestone with red mud and processing in pyrosection, we are in a position to claim:-
1. That, due to high percentage of moisture in red mud we may face problem in feeding of material up to raw material grinding stage, however this may be over come if we can afford sundry the material (if space is available) or by installing jamming replant liners. We may also face problem in processing the red mud during rainy season due to possibility of increasing percentage of moisture.

2. That, during three days of trial study, we have not faced any process problem in the clinkerisation unit. There has not been any coating formation in the kiln riser duct and not faced any un-burnt coal residue at the Kiln inlet confirms satisfactory clinkerisation in the kiln.

3. That, there has not been any change in the Quality parameters of the clinker and cement before and after use of red mud as evident from the results achieved.

4. That, emission level from the stack for various parameters, Dioxins and Furans along with ambient air before and after use of red mud reveals that no change in parameters are evident, confirms that red mud may be used without extra load of pollution in the Cement manufacturing.

5. That, Red mud is being used successfully for more than four months after consent from regulatory authority after witnessing the trail run.

Based on above achieved results we may conclude that there is no change in process, quality and emission level observed, therefore it may be concluded that Red Mud may be utilized by the cement industry in place of additive to protect the environment and to conserve the natural resources like laterite/ Iron ore.
“Cement/Aluminum Industry should be directed by regulatory authority to use red mud on cost sharing basis to avoid contamination of land used for storage and environment concern for Win - Win situation for both the industry.”