huge markets for magnesia in concretes and other cementitious composites

John Harrison, TecEco Pty. Ltd., Tasmania, Australia

Huge markets for magnesia in concretes and other cementitious composites

Presentation downloadable from www.tececo.com


New Uses = New Markets

Demand in this industry has been static for some years. New markets can change all that.

Demand for Caustic Calcined and Less Reactive Grades through growth in the production and use of “MgO” boards

Based on magnesium oxychloride/sulfate cements + or – Mg phosphate cements

Reinforced with natural and synthetic fibres.

Huge potential demand for cements using reactive MgO

Discovery that reactive MgO could be blended with other hydraulic binders such as Portland cement + or – pozzolans. (Patented TecEco -Harrison)

A powerful and useful new tool in cement chemistry affecting all properties including rheology, bleeding, dimensional stability and durability to name but a few.

Rekindled interest in environmentally friendly magnesium carbonate cements.

Eco-Cements with a high proportion of reactive MgO (Patented TecEco - Harrison)

Reactive MgO 95 – 5% Hydraulic cement e.g. PC 5 - 95%.

Pure reactive MgO cements (Cambidge Uni Group. Old technology revisited)

Magnesium oxy chloro carbonate cements. (Imperial College Novacem. Old technology with a new spin?)

June 2010


New Demand for New Forms of MgO Reactive Magnesia

MgO calcined below say about 750 oC and fine ground to say <<45 micron. Engineered particle size, size range and reactivity.

Including nano sizes or separate category?

Caustic Calcined MgO

MgO “light burned” at less that say 1000 oC and ground relatively fine say <75 micron

Dead Burned MgO

MgO high temperature calcined, mostly periclase and often ground < 100 micron.

Fused

June 2010

Reactivity

Reactivity

Lat t ice

Energy

Lat t ice

Energy

Focus on new uses for reactive MgO

Reactivity is a function of the energy input (temperature of calcination & time heat applied), impurities, grind size, ore characteristics and other factors. The actual energy input is most important as energy in excess of that required to break the Mg~CO3 bond goes into lattice energy


Why Reactive MgO?

June 2010

Lattice energy Periclase > Hydration energy Mg++

3795 kJ/mol-1 > 1926 kJ/mol-1

Periclase has a high lattice energy and both cations and anions are in octahedral (6) coordination.

In solution in the first hydration shell six water molecules are held tightly in place by electrostatic interactions between the two positive charges on the Mg++ ion and the partial negative charge on the oxygen molecule of each water. This structure electrostatically propagates outward many layers deep.

The specific surface area of MgO is a proxy for lattice energy and the lower the temperature of calcination the more reactive the MgO.

Rapid formation of hydrated magnesium carbonates.

See: Reactive Magnesia The Importance of the Temperature of Calcination at http://www.tececo.com/technical.reactive_magnesia.php

Rapid formation of Brucite

e.g Tec-Cements e.g Eco-cements


Deployment of new Cements Quality issues

A narrower bell curve of properties such as reactivity and particle size is required

Price challenges

Reactive magnesia must compete with Portland cement

Environmental & bureaucratic challenges

Carbon caps or taxes will apply to emissions from the production of MgO

June 2010

After inventing our Tec, Eco and Enviro cements TecEco set out to figure out new ways of making reactive MgO and design a kiln that could solve the environmental sustainability challenge and in the process we have solved the environmental, carbon, quality and price issues as well


Making Cheaper Better Reactive MgO

June 2010

Step Process Conditions Upsides DownsidesMgCO3=>MgO +↑CO2 600-750 OC Known

technologyEmissions, fossil fuel energy. Blight on landscapes.

Step 1 of 2

Mg Silicate + ↓CO2 => Mg Carbonate

180oC/150bar Sequestration step

Fossil fuel energy?

Step 2 Mg Carbonate => MgO + ↑CO2

650-750 OC Calcination step

Process energy + re release CO2

Optional Step before

Mg Silicate => Mg Salt (MgCl2)

Various Known acid extraction

Expensive As acid corrosive.

Step 1 of 2

Mg Salt + ↓CO2 => Mg Carbonate (Nequehonite?)

Room temp. Use waste. Carbon credits.

Step 2 of 2

Mg Carbonate => MgO + ↑CO2

650-750 OC Calcination step

Process energy + re release CO2

We have to ask ourselves why we are still digging holes in the ground. The industry would encounter far less bureaucratic blocking, make more money and go a long way towards solving global warming using the last option in black with a light green background.

Carbon neutral

TecEcoPref –erred


The TecEco Tec-Kiln - Changing the Way we Make Magnesia

June 2010

Operates in a closed system and therefore does not release CO2 or other volatiles substances to the atmosphere

Can be powered by various potentially cheaper non fossil sources of energy such as intermittent solar or wind energy.

Grinds and calcines at the same time thereby running 25% to 30% more efficiently.

Produces more precisely definable product. (Secret as disclosure would give away the design)

The CO2 produced can be sold or re-used.

Cement made with the Tec-Kiln will be eligible for carbon offsets.

The Tec-Kiln is a top secret kiln being developed for low temperature calcination of alkali metal carbonates and the pyro processing and simultaneous grinding of other minerals such as clays.

The TecEco Tec-Kiln makes no releases and is an essential part of TecEco's plan to sequester massive amounts of CO2 as man made carbonate in the built environment.

The TecEco Tec-Kiln has the following features:

MgCO3

MgO

CO2

Tec-Kiln = Problems Solved = Way Forward


Gaia Engineering

June 2010

Mg Carbonat

esIndustrial CO2

MgO

TecEco Tec-Kiln

TecEco Eco-Cements

AggregatesBitter

ns or Brines

TecEco Tec-Cements

Built Environment

MgCl2 Proce

ss

Concretes and Other CompositesOther

waste

Building

waste


New Players re CO2 Capture = > Building Materials

June 2010

13th July 2002 – Fred Pearce in New Scientist about TecEco technology:

“THERE is a way to make our city streets as green as the Amazon rainforest. Almost every aspect of the built environment, from bridges to factories to tower blocks, and from roads to sea walls, could be turned into structures that soak up carbon dioxide- the main greenhouse gas behind global warming. All we need to do is change the way we make cement.

2008 - Calera Corporation

Brett Constance backed by Vinod Khoshla and others

Attracting considerable criticism from scientists as upsets pH balance resulting in reduced inability of oceans to absorb H2O (Ken Caldiera and others)

Has so far produced the most expensive carbonate in the world

2008 - Greensols Process (Cuff and Blake)

A fundamentally good idea stalled by lack of finance

2009 - Newcastle Group (Eric Kennedy and Others)

Secretive


The Kyoto Process – A Political and Economic Dilemma

June 2010

Yes No

CO2 is adversely affecting climate

False

True

Cost $GlobalRecession

Survival

EconomicPoliticalSocialEnvironmentalCatastrophe

Yes No

Action

False

True

Profit $

Profit $

EconomicPoliticalSocialEnvironmentalCatastrophe

Action

The TecEco Alternative

Cost $GlobalRecession

The Current Situation

CO2 is adversely affecting climate

Money Saved $

Survival

Profit $

A problem that’s never been easy to come to grips with and that our national and international political systems were not designed to handle

By solving problems like global warming profitably there is no dilemma and the world can move forward


The Global Warming Problem

June 2010

The global CO2 budget is the balance of CO2 transfers to and from the atmosphere. The transfers shown below represent the CO2 budget after removing the large natural transfers (shown to the right) which are thought to have been nearly in balance before human influence.

Global Carbon FlowsAfter: David Schimel and Lisa Dilling, National Centre for Atmospheric Research 2003

Atmospheric increase

= Emissions from fossil fuels

+ Net emissions from changes in land use

- Oceanic uptake

- Missing carbon sink

3.2 (±0.2) 6.3 (±0.4) 2.2 (±0.8) 2.4 (±0.7) 2.9 (±1.1)

From: Haughton, R., Understanding the Global Carbon Cycle. 2009, Woods Hole Institute at http://www.whrc.org/carbon/index.htm

Woods Hole Carbon Equation (In billions of metric tonnes)


Net Atmospheric Increase in Terms of Billion Tonnes CO2

June 2010

Atmospheric increase



- Oceanic uptake


3.2 (±0.2) 6.3 (±0.4) 2.2 (±0.8) 2.4 (±0.7) 2.9 (±1.1)

Converting to tonnes CO2 in the same units by multiplying by 44.01/12.01, the ratio of the respective molecular weights.Atmospheric increase



- Oceanic uptake


11.72 (±0.2) 23.08 (±0.4) 8.016 (±0.8) 8.79 (±0.7) 10.62 (±1.1)

From the above the annual atmospheric increase of CO2 is in the order of 12 billion metric tonnes.

Using the Figures from Woods Hole on the Previous Slide


How Much Man Made Carbonate to Solve Global Warming?

June 2010

If a proportion of the built environment were man made carbonate, how much would we need to reverse global warming?

MgO + H2O => Mg(OH)2 + CO2 + 2H2O => MgCO3.3H2O40.31 + 18(l) => 58.31 + 44.01(g) + 2 X 18(l) => 138.368 molar masses.44.01 parts by mass of CO2 ~= 138.368 parts by mass MgCO3.3H2O1 ~= 138.368/44.01= 3.144

12 billion tonnes CO2 ~= 37.728 billion tonnes of nesquehoniteorMgO + H2O => Mg(OH)2 + CO2 + 2H2O => MgCO340.31 + 18(l) => 58.31 + 44.01(g) + 2 X 18(l) => 84.32 molar masses.CO2 ~= MgCO344.01 parts by mass of CO2 ~= 84.32 parts by mass MgCO31 ~= 84.32/44.01= 1.9159

12 billion tonnes CO2 ~= 22.99 billion tonnes magnesite


So How Much Magnesia Would be Sold?

June 2010

How Much Money = How Much Magnesia X Price + Value Carbon Credits – Costs Production

Not enough to show on graph


Natural Sinks for Carbon

June 2010

Modified from Figure 2 Ziock, H. J. and D. P. Harrison. "Zero Emission Coal Power, a New Concept." from http://www.netl.doe.gov/publications/proceedings/01/carbon_seq/2b2.pdf by the inclusion of a bar to represent sedimentary sinks

This industry could profitably be involved in modifying the carbon cycle by facilitating a new man made carbon sink in the built environment. The need for a new and very large sink can be appreciated by considering the balance sheet of global carbon in the crust after Ziock, H. J. and D. P. Harrison depicted.


Carbon Capture = Carbon Credits

June 2010


June 2010

Many magnesium compounds are characterised by a mixture of Ionic and Polar Bonding and this accounts for many of their properties

After: D’Souza, N. A., P. Braterman, et al. "Flame retardant nano composites with layer double hydroxides." Retrieved 15 October 2006, 2006.

At http://www.tececo.com/technical.nanocomposites.php we discuss the amazing ability of magnesium hydroxide to form complex layered double hydroxide (LDH) compounds with many other substances including water and CO2. This property is important because it is why for example magnesium hydroxide hydrates can prevent autogenous shrinkage of concrete and why magnesia is so useful for locking up wastes. It is also related to how it can bond so easily with other substances.

Understanding Magnesium Compounds including Nano Composites


Understanding Magnesium Compounds including Nano Composites

June 2010

Cellulose

Brucite. Polar bound layers of ionically bound atoms

Strongly differentially charged surfaces and polar bound water account for many of the properties of brcute

Brucite hydrates. Polar bound layers of ionically bound atoms


A Classification of Magnesium Cements - 1

June 2010

1. Cements that rely on the chemical reaction of magnesia with another component.1.1 Reactions causing the formation of magnesium oxychloride, magnesium oxysulfate or derivatives. (Excluded in claim 1)1.1.1 As a base with chlorides or sulfates. E.g Aluminum, magnesium, calcium, zinc or copper chloride or sulfate.1.1.2 As a base with acids. e.g. Sulfuric or hydrochloric acids1.1.3. As a base with partially substituted acids or salts containing chloride or sulfates. e.g. Reaction with calcium aluminate trisulphate, a double salt, delivering sulphate

for the formation of magnesium oxy sulfate.1.2 Chemical reaction or interaction with substances that cause carbonation.1.2.1 As a base with organic substances delivering CO3

--. e.g Carbonic acid. (See also 1.3.1)

1.2.2 As a base with inorganic substances delivering CO3--. e.g. Sodium carbonate and calcium carbonate, CO2 or a chemical that releases CO2. The CO2 which then

dissolves in water forming carbonic acid. (Carbonic acid will force rapid carbonation of magnesia whereby various magnesium carbonates are formed in situ.)1.3 Chemical reaction with acidifying agents.1.3.1 Organic acidifying agents. E.g. Citric acid, acetic acid and other carboxylic or polycarboxylic acids. (Such organic acidifying agents may also deliver carbonate

(CO3--.) and thus fall into the category 1.2.1 above.)

1.3.2 Inorganic acidifying agents. Acidifying acids may assist the dissolution and reformation of carbonate or act as accelerators or retardants depending on the mix.1.3.3 Neutralization of acids e.g low molecular weight organic acids from the breakdown of pectin and lignin in wood prior to use of an ingredient such as in this case

wood1.4 Cements that include an soluble or acid phosphate and result in chemical precipitation of insoluble magnesium phosphates.1.5 Chemical reaction in the form of ion exchange. The use of magnesia for ion replacement in a more soluble substance rendering the substance less soluble.1.5.1 The replacement of Na+ or K+ is waterglass. e.g the replacement of Na+ or K+ in sodium or potassium silicates resulting in an insoluble precipitate of magnesium

silicate.1.6 Chemical reaction as a so called “activator” or “accelerator” (Note that Mg is not a network former in geopolymeric binders as claimed rather arbitrarily by many.)1.7 Cements that rely on prior addition of magnesia to another substance resulting in chemical and physical interaction sequentially prior to the addition of other binder

components1.7.1 The interaction of magnesia with schist or the waste from coal washings prior to the addition of other binders such as Portland cement1.7.2 The reaction of magnesia with low molecular weight compounds e.g. wood acids prior to further additions.1.8 The reaction of substances in a binder prior to addition of the reactants to magnesia1.9 Chemical interaction with other salts (e.g. borax)1.10 Interaction with some other substance

Novacem


A Classification of Magnesium Cements - 2

June 2010

2. Cements in which the main role of magnesia is in electrostatic bonding reactions. Cements that rely on the strong non-ionic, non covalent bonding of Mg++ to a negative region of a molecule. E.g. Mg++ to oxygen - similar to hydrogen bonding.2.1 Bonding of Mg++ to oxygen in cellullosic compounds and oxygen in water.2.2 Bonding and complexing with water. The hydration energy of Mg++ is very high (Note1) In solution Mg++ complexes with water more readily than Ca++ forming ions of the general form [Mg(H2O)N]2+. Mg++ can also hydroxylate forming H3O+ and Mg+OH and hydrated forms of Mg+OH. These complexes greatly affect the rheology of water particularly in the presence of substances displaying strong hydrogen bonding, wherein Mg++ is attracted to the net negative charge on oxygen.2.3 Electrostatic and sorption bonding to activated carbon3 Cements that use dead burned rather than reactive magnesia.3.1 Cements that use dead burned rather than reactive magnesia to deliberately induce expansion.4. Cements that rely on the physical properties of magnesia rather than reaction. E.g. Cements that use dead burned rather than reactive magnesia to increase fire retarding properties•Cements that have a high proportion of calcium carbonate in them. (May also fall into 1.2.2 above)5.1 Cements that include magnesia sourced from dolomite or5.2 Cements that have been blended to include calcium carbonate. (excluded as we teach this is obviously not desirable)6. Cements that do not include another hydraulic cement. Cements that may include magnesia but do not include a hydraulic cement like Portland cement. 7. Citations in which the use of magnesia is incidental and unnecessary8. Citations that are nothing whatsoever to do with the TecEco patent or for which insufficient information has been provided9. Complex mechano or nano composites.

Note 1 Mg++ has a hydration energy of 1926 kJ/mol compared to 1579 kJ/mol for Ca++ [1,2]. Six water molecules in octahedral coordination surround the Mg2+

ion in a rigid first solvent shell [3]. For comparison, the exchange rate of water in the hydration shell of Ca2+ ions is ~1000-fold faster than for Mg2+ ions [4].

Ref 1 Slaughter M, Hill RJ: The influence of organic matter in organogenic dolomitization. J Sed Petrol 1991, 61:296-303. Ref 2 Wright DT, Wacey D: Precipitation of dolomite using sulphate-reducing bacteria from the Coorong Region, South Australia: Significance and

implications. Sedimentology 2005, 52:987-1008. Publisher Full Text Ref 3 Kluge S, Weston J: Can a hydroxide ligand trigger a change in the coordination number of magnesium ions in biological systems. Biochemistry

2005, 44:4877-4885. PubMed Abstract | Publisher Full Text Ref 4 Fenter P, Zhang Z, Park C, Sturchio NC, Hu XM, Higgins SR: Structure and reactivity of dolomite (104)-water interface: New insights into th

dolomite problem. Geochim Cosmochim Acta 2007, 71:566-579. Publisher Full Text


Why MgO in Hydraulic Binder Systems? Mg in solution is

strongly kosmotrophic => profound effects on rheology

increased surface tension reduces bleeding and thus early age plastic shrinkage.

Long term shrinkage eliminated.

Replaces free lime (Portlandite Ca(OH)2) in concretes

Free lime (Portlandite, Ca(OH)2) in concretes is too reactive.

In Tec-Cement binders free lime is encouraged to react with pozzolans forming more calcium silicate hydrates. It is replaced by brucite and brucite hydrates which take on the major function of long term pH control and eliminate autogenous shrinkage.

Dramatically improves durability

Lower solubility and reactivity (Eh & pH conditions) of Brucite

Expansive carbonation resulting in very tight surfaces preventing entry of aggressive ions.

June 2010


Magnesium Compounds

June 2010

Mineral (or Product)

Formula Partial Pressures

Ph Hard ness

Habit

Brucite Mg(OH)2 10.2 2.5 - 3

Blocky pseudo hexagonal chrystals.

Brucite Hydrates Mg(OH)2.nH2O Not much known!

Dypingite Mg5(CO3)4(OH)2·5H2O Low CO2, H2O

High? ? Platy or rounded rosettes

HydromagnesiteGiorgiosite

Mg5(CO3)4(OH)2·4H2O High? 3.5 Include acicular, lathlike, platy and rosette forms

Artinite Mg2(CO3)(OH)2•3(H2O) 2.5 Bright, white acicular sprays

Magnesite MgCO3 3.9 Usually massive

Barringtonite MgCO3·2H2O 2.5 Glassy blocky crystals

Nesquehonite MgCO3·3H2O Presence H2O

Variable?

2.5 Acicular prismatic needles

Lansfordite MgCO3·5H2O 2.5 Glassy blocky crystals

Note: Many other possible forms. Abiotic and biotic precipitation pathways and a lack of thermodynamic optimisation data

Carbonates


Magnesium Carbonate Phases

June 2010


Why Brucite in Dense Concretes?

June 2010

Pourbaix diagram steel reinforcing

Brucite

Improves rheology (see http://www.tececo.com/technical.rheological_shrinkage.php)

Prevents shrinkage and cracking (see http://www.tececo.com/technical.rheological_shrinkage.php)

Provides pH and eH control. Reduced corrosion. Stabilises CSH with pozzolanic reaction (Encouraged)

Provides early setting even with added pozzolans

Relinguishes polar bound water for more complete hydration of PC (thereby preventing autogenous shrinkage?)

Surface charge on magnesium oxideMgO + H2O => Mg(OH)2


At 2.09% of the crust magnesium is the 8th most abundant element

Nesquehonite

Has an ideal shape that contributes strength to the microstructure of a concrete

Forms readily at moderate and high pH in the presence of CSH, our catalyst. (Nucleation mechanism?)

The hydration of PC => alkalinity dramatically increasing theCO3

-- levels that are essential for carbonation.

Significant molar volumeexpansion.

Captures more CO2 than Calcium

Ideal wet dry conditions are easily and cheaply provided. Forced carbonation is not required (Cambridge uni and others)

Why Nesquehonite in Carbonating Binder Systems?

June 2010

3H2O + CO3---- + Mg++ => MgCO3·3H2O

XRD Pattern Nesquehonite

Nesquehonite

%5284

44

3

2

MgCO

CO

%43101

44

3

2

CaCO

CO


TecEco Formulations Tec-Cements (5-20% MgO, 80-95% OPC)

contain more Portland cement than reactive magnesia. Reactive magnesia hydrates in the same rate order as Portland cement forming Brucite which uses up excess water reducing the voids:paste ratio, increasing density and possibly raising the short term pH.

Reactions with pozzolans are more affective. After much of the Portlandite has been consumed Brucite tends to control the long term pH which is lower and due to it’s low solubility, mobility and reactivity results in greater durability.

Other benefits include improvements in density, strength and rheology, reduced permeability and shrinkage and the use of a wider range of aggregates many of which are potentially wastes without reaction problems.

Eco-Cements (20-95% MgO, 80-5% OPC) contain more reactive magnesia than in Tec-Cements. Brucite in permeable materials

carbonates forming stronger fibrous mineral carbonates and therefore presenting huge opportunities for waste utilisation and sequestration.

Enviro-Cements (5-15% MgO, 85-95% OPC) contain similar ratios of MgO and PC to eco-cements but in non permeable concretes

brucite does not carbonate readily.

Higher proportions of magnesia are most suited to toxic and hazardous waste immobilisation and when durability is required. Strength is not developed quickly nor to the same extent.

June 2010


Conclusion

June 2010

To avoid carbon costs and other imposts maybe the industry should consider making MgO in different way.

The industry can gain a competitive advantage by being the first to produce product without releases and utilising wastes .

MgCl2 + CO2 => MgCO3.3H2O => MgO +CO2

Magnesium oxide on hydration and/or carbonation becomes many different minerals all of which should be considered as products with huge marketing opportunities such as for carbon sequestration.

There must be much more focussed research into this wide array of new products as they are sold into technical markets.

MgO of better quality and lower price is required to compete with Portland cement.

As in the cement industry the MgO industry should consider forming an association which at an industry level carries out the basic research required to move into new markets.

huge markets for magnesia in concretes and other cementitious composites

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