1. Techno-economic and environmental analysis of alkali activated materials containing phosphogypsum and blast furnace slag
Goodafternoon! My name is Katrijn and I’m from the University of Hasselt and the University of Leuven. My presentation is about the techno-economic and environmental analysis of alkali activated materials containing phosphogypsum and blast furnace slag.
Katrijn GIJBELS1,2, Yiannis PONTIKES2, Remus Ion IACOBESCU2, Sonja SCHREURS1,
Wouter SCHROEYERS1, Tom KUPPENS1
1 Hasselt University, Department of Nuclear Technology, Agoralaan, 3590 Diepenbeek, Belgium
2 KU Leuven, Department of Materials Engineering, Kasteelpark Arenberg 44, 3001 Leuven, Belgium

2. Content Introduction Proces design Economical feasibility model
Production of cement
Alkali activated materials
Wastes of concern
Goals
Proces design
Proces flow diagram
Material and energy balances
Economical feasibility model
Environmental analysis
First I will give you a short introduction of my case, were I will speak about the production of cement, alkali activated materials, the wastes of concern and the goals of this research.

3. 1. Production of cement
In 2008, worldwide cement production 2.9 billion tonnes
Contribution of 5-8% of global CO2 emissions (high temperature decomposition of limestone)
Demand for cement is growing (especially in the developing world)
Limited reserves of limestone (primary raw material)
Increasing carbon taxes
Cement industry faces challenges, and urgent need for alternative binders
In 2008, worldwide cement production was 2.9 billion tonnes. This enormous volume is associated with a significant environmental impact because the production contributes 5 to 8% of global CO2 emissions because of the high temperature decomposition of limestone. The demand for cement is still rising and there are limited reserves of limestone, which is the primary raw material in cement production. This all together, combined with increasing carbon taxes, imparts challenges for the cement industry and there is an urgent need for alternative binders.

4. 2. Alkali activated materials
Alternative binders which are being discussed today
Class of amorphous alkali calcium-aluminosilicates
Synthesis by mixing a high pH activating solution (e.g. 10M NaOH) with a solid calcium aluminosilicate source
Hardening after 1-10 hours at room temperature
Mechanical properties (e.g. strength, porosity) comparable or even better than cement
Technology provides opportunity for utilisation of industrial solid residues containing calcium-, aluminium-, and/or siliciumoxides (e.g. fly ash, metallurgical slag, mining wastes, etc.)
Alkali activated materials are a class of alternative binders for cement which are being discussed today. From the chemical point of view, they consist of amorphous alkali calcium-aluminosilicates and they can be synthesised by mixing a high pH solution together with a solid calcium aluminosilicate source. This will harden after 1 to 10 hours at room temperature and mechanical properties are comparable or in some cases even better than traditional cement. What is also very important to mention is that alkali activated materials can be made out of industrial solid residues, particularly the ones containing calcium-, aluminium- and/or siliciumoxides like fly ash or metallurgical slags.

5. 3. Wastes of concern Phosphogypsum (from phosphate industry)
Blast furnace slag (from iron industry)
Industrial solid residues containing calcium-, aluminium-, and/or siliciumoxides
Chosen based on capacity, homogeneity and urgency for Flanders
Presence of minor components has a negative impact on indoor and wider environment associated with the
life-cycle of building materials (e.g. heavy
metals, naturally occuring radionuclides)
Reduced valorisation currently, research
necessary to widen field of application
Flanders: disposal costs €175 per ton
Flemish industrial wastes which were chosen to produce alkali activated materials are phosphogypsum and blast furnace slag. Phosphogypsum comes from phosphate production, while blast furnace slag originates from iron production. They contain calcium-, aluminium-, and/or siliciumoxides and were chosen based on capacity, homogeneity and urgency for Flanders. However, the presence of minor components in these wastes, like heavy metals and radionuclides, complicates their valorisation. Therefore, research is necessary to widen their field of application because disposal of waste is not sustainable and is also expensive for industry.

6. 3. Wastes of concern Phosphogypsum (from phosphate industry)
Blast furnace slag (from iron industry)
Industrial solid residues containing calcium-, aluminium-, and/or siliciumoxides
Chosen based on capacity, homogeneity and urgency for Flanders
Presence of minor components has a negative impact on indoor and wider environment associated with the
life-cycle of building materials (e.g. heavy
metals, naturally occuring radionuclides)
Reduced valorisation currently, research
necessary to widen field of application
Flanders: disposal costs €175 per ton
Here we reached the focus of my PhD, which is the physico-chemical immobilisation of heavy metals and radionuclides in residue-based alkali activated materials. Because lab-scale experiments are still ongoing, I started last year, my TEA and LCA are not finished yet, but however, I will present you preliminary results.
My PhD: Physico-chemical immobilisation of heavy metals and radionuclides in residue-based alkali activated materials

7. 4. Goals Techno-economic analysis Environmental analysis
Identify the crucial variables for rendering the production of
alkali activated building materials from Flemish industrial solid
residues profitable
Environmental analysis
Based on a life cycle assessment,
environmental aspects of the proces will be
expressed in global warming potential (GWP)
For the TEA, the goal is to identify the crucial variables for rendering the production of alkali activated building materials from Flemish industrial solid residues profitable, and based on a life cycle assessment, to express the environmental aspects in global warming potential.

8. Content Introduction Proces design Economical feasibility model
Production of cement
Alkali activated materials
Wastes of concern
Goals
Proces design
Proces flow diagram
Material and energy balances
Economical feasibility model
Environmental analysis

9. 1. Proces flow diagram
Here we see the preliminary process flow diagram. As input materials, we have our 2 waste streams, the high pH solution, aggregates and energy. When they come from industry, they are typical wet. The waste streams first need to be dried, milled and mixed, whereafter they are mixed with the high pH solution and aggregates. Then this mix will harden after 1-10 hours and we get as output materials: alkali activated material and emission. Based on this preliminary process flow diagram, material and energy balances are calculated.

10. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium
In order to estimate an appropriate capacity for a realistic production facility, there are 3 possible limiting factors: (1) the market size, (2) availability and amount of waste, and (3) typical equipment size. Lab or pilot plant data are necessary and the transportation of input materials is not considered here because all input materials are assumed to be manufactured in Belgium.

11. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium

12. 2. Material and energy balances
Figure : Global cement production and percentage of global population in urban areas since 1950
In the first figure we see the global cement production since the 1950s and we can roughly estimate that the global market size will not decrease. If we go more locally, we see in the second picture a map op Belgium showing its cement plants which produce about 2.62 million tons per year for the domestic market.
Figure : Map of Belgium showing cement plants
2.62 Mt/yr cement production for domestic market

13. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium
For this reason, … +
2.62 million tons

14. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium

15. 2. Material and energy balances
38 Mt
0.25 Mt/y
1.12 Mt/y
The picture shows us the availability of blast furnace slag and phosphogypsum in Belgium. As you can see, 38 million tons of phosphogypsum are already stockpiled since the 1970s, and there is still a yearly production of 0.25 million tons. For blast furnace slag, production is 1.12 million tons per year, and this is consequently the limiting stream. Considering a 20-year operational period, we can conclude that there is sufficient phosphogypsum available during the complete lifetime of the plant.
Blast furnace slag production 1.12 Mt/y  limiting stream
A hypothetical plant is considered to have a lifetime of 20 years, rate of production is therefore calculated based on a 20-year operational period  sufficient phosphogypsum available

16. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium

17. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium

18. 2. Material and energy balances
Typical cement production plant:
Capacity – tons/year
Mostly equipped with production lines of tons
Steps in production process of alkali activated materials:
Drying of precursors
Milling of precursors
Pre-mixing of precursors
Typical capacity of commercial available equipment?
A typical cement production plant has a capacity of – tons per year and is mostly equipped with production lines of tonnes. If we look again to our process flow diagram, we see that for example drying and milling are necessary steps, so what is the typical capacity of commercial available equipment?

19. 2. Material and energy balances
To estimate an appropriate capacity for a realistic production facility, 3 possible limiting factors
Lab or pilot plant data are necessary
Transportation of input materials is not considered because all input materials are assumed to be manufactured in Belgium
If we assume for example a production facility of 2 million tons per year, the limiting factor will be the availability and amount of waste… +
2.62 million tons
2 million tons

20. 2. Material and energy balances
Max Mt/y
3 ovens
0.5 Mt/y
2 Mt/y
… and therefore, the production capacity will be estimated for 1.12 million tons of blast furnace slag as input per year. And based on that, we can calculate that …

21. Content Introduction Proces design Economical feasibility model
Production of cement
Alkali activated materials
Wastes of concern
Goals
Proces design
Proces flow diagram
Material and energy balances
Economical feasibility model
Environmental analysis

22. Economical feasibility model
Total capital investment =
Fixed-capital investment (direct + indirect costs)
Working-capital investment (ratio working capital to total capital investment varies from 10-20%)
This table provides an estimation of the necessary investments in percentage based on (1) the process flow diagram and (2) the material and energy balances. These investments were divided into fixed-capital investment and working capital investment. Fixed-capital investment can be divided into direct and indirect costs. An example of direct costs is the cost for buying dryers or mixers, while indirect costs are for example fees. What is also important to mention here is that disposal costs for blast furnace slag and phosphogypsum are avoided.

23. Content Introduction Proces design Economical feasibility model
Production of cement
Alkali activated materials
Wastes of concern
Goal of the analysis
Proces design
Proces flow diagram
Material and energy balances
Economical feasibility model
Environmental analysis

24. Environmental analysis
What to choose?
International standard for LCA: ISO 14040, 14044
Software tool to set up the LCA model: SimaPro 7 (PRéConsultants 2010)
Assessment method: IPCC 2007 GWP 100a method (PRéConsultants 2008)
Influence of valorisation method: ReCiPe midpoint method (Goedkoop et al., 2013)
Other methods?

25. Thank you for your attention.
Questions?