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Mon Sep 24, 2018, 10:26 PM

Temperature Dependence of Biochar Hardness, a Factor in Displacing Coal Based Coke in Steel Making.

Last edited Mon Sep 24, 2018, 11:06 PM - Edit history (2)

The paper I'll discuss in this brief post is this one: Dynamic Hardness of Charcoal Varies According to the Final Temperature of Carbonization (Hein et al Energy Fuels, 2018, 32 (9), pp 96599665)

I am a critic of the so called "renewable energy" industry. My main argument is that it has proved demonstrably ineffective at climate change. At the outset of this century it was decided to "invest" trillions of dollars in this pixilated scheme - this on a planet where billions of people lack access to electricity, clean water, and basic sanitation - with the result that the rate of accumulation of the dangerous fossil fuel waste carbon dioxide has accelerated, not decelerated. The fastest growing source of energy - as measured in new exajoules of production - in this century has been dangerous fossil fuels, the increase lead by coal, which increased by 60 exajoules as compared to the nearly 130 exajoules of additional dangerous fossil fuel combustion added to the world energy equation since the year 2000.

Another criticism I have of the so called "renewable energy" industry is that it is not really "renewable." As I pointed out in a recent post in this space on the carbon cost of production of metals, the metal intensity of so called renewable energy dwarfs the requirements of the much cleaner source of energy, nuclear energy.

I quoted this paper: Metals for a Low Carbon Society (Vidal et al Nature Geoscience volume 6, pages 894896 (2013):

this transition [to so called "renewable energy"] will also cause much additional global demand for raw materials: for an equivalent installed capacity, solar and wind facilities require up to 15 times more concrete, 90 times more aluminum, and 50 times more iron, copper and glass than fossil fuels or nuclear energy (Supplementary Fig. 1). Yet, current production of wind and solar energy meets only about 1% of global demand, and hydroelectricity meets about 7% (ref. 2)...

... If the contribution from wind turbines and solar energy to global energy production is to rise from the current 400 TWh (ref. 2) to 12,000 TWh in 2035 and 25,000 TWh in 2050, as projected by the World Wide Fund for Nature (WWF)7, about 3,200 million tonnes of steel, 310 million tonnes of aluminium and 40 million tonnes of copper will be required to build the latest generations of wind and solar facilities (Fig. 2). This corresponds to a 5 to 18% annual increase in the global production of these metals for the next 40 years. This rise in production will be added to the accelerating global demand for ferrous, base and minor metals, from both developing and developed countries, which inflates currently by about 5% per year5,6..

Although, as I showed in the post, aluminum is dependent upon petroleum coke and steel on traditional coke from coal, I am always interested in alternatives, to the extent to which they can be realized.

That is the subject of the cited paper. (Historically steel was made using wood as a carbon source, albeit on a planet with a small fraction of its current population, and certainly not a population "investing" in bat and bird grinding wind turbines that turn to landfill every 20 years or so.)

From the introduction:

The steel industry uses iron ore and coking coal in the blast furnace to produce iron. The process consists of converting iron ore into pig iron and steel, which is performed using reducing agents based on carbon and hydrogen.(1) Coal can be replaced by vegetable charcoal produced from pyrolysis.(2,3) Charcoal presents many advantages over mineral coal because it is renewable, it is less polluting, it has a low ash content, it is practically free of sulfur and phosphorus, it is more reactive, the production and transport process is not centralized, and it provides foreign exchange savings with the elimination of imports of fossil fuels.(4)

Brazil has been pointed out as the only country that industrially uses charcoal as a source of carbon monoxide and heat in blast furnaces for steel production.(5) The main consumers of the charcoal are pig iron, steel, and iron alloy industries and, to a lesser extent, trade and residential consumers.(3) According to Vieira et al.(6) one of the problems faced by the Brazilian steel industry is the heterogeneity of the charcoal used in the steel fabrication with reference to physical, mechanical, and chemical properties and the low yield in the carbonization processes currently used.

Variations in wood and carbonization processes led to variations in the gravimetric yield and charcoal quality.(7−9) High wood density, lignin content, and low ash content are characteristics that may be considered as wood quality indices for charcoal production.(10,11) With regard to the quality of charcoal, a higher fixed carbon (FC) content and lower ash and volatile contents are associated with a high lignin content and low holocellulose and extractive contents in wood.(10)...

...Charcoal has two main functions in the blast furnace, providing energy for the process in the form of heat and being the reducing agent of iron ore,(1) but also the charcoal layers must mechanically withstand the weight of the iron ore inside the blast furnaces.(14) According to Assis et al.,(8) the mechanical characteristics of charcoal are also controlled by the characteristics of precursor raw material, for instance, specific gravity, moisture, chemical composition, and anatomical features, and also by the two key carbonization settings: final temperature and heating rate.

To our knowledge, there is no standardized method for evaluating strength characteristics of vegetable charcoal. Traditional methods to evaluate the mechanical behavior of charcoal are neither precise nor repeatable. Among the mechanical properties of the charcoal, the friability has been determined by means of the drum test.(15) To carry out the mechanical characterization in the charcoal sample, 500 g of material is placed in a fixed rotating drum that rotates at 30 rpm around a horizontal axis, 30 cm in diameter and 25 cm in length.

The authors examine several different species of trees as a source of charcoal, as well as the effect of temperature and other conditions on the preparation of chars.

Here's a picture of their hardness tester and some charcoal:

The caption:

Figure 1. (A) Automated portable hardness tester, DPM3, (B) dropping component and indenter (arrow), and (C and D) indentation after the DH test on the charcoal specimen produced under 300 C.

DH = dynamic hardness.

A graph of some findings:

The caption:

Figure 2. Average and standard deviation of DH (MPa) and wood density (kg/m3) of the investigated wood specimens per VM. Means of wood density (line) followed by the same capital letters and means of DH (bars) followed by the same lowercase letters do not differ by 5% of significance from the Tukey test.

The relationship between the density of wood and the hardness:

The caption:

Figure 3. Relationship between DH and density of wood.

The caption:

Figure 4. Variation of DH of wood and charcoal produced under 300, 450, 600, and 750 C. Means followed by the same letters do not differ by 5% of significance from the Tukey test

And the density of the charcoal as a function of the temperature of pyrolysis:

The caption:

Figure 4. Variation of DH of wood and charcoal produced under 300, 450, 600, and 750 C. Means followed by the same letters do not differ by 5% of significance from the Tukey test.

The relationship between charcoal yield and hardness:

The caption:

Figure 6. Relationship between DH and wood to charcoal yield, produced under 300, 450, 600, and 750 C.

The authors claim that the species of wood doesn't matter quite as much as the temperature of pyrolysis.

DH of Eucalyptus charcoal decreased with the increase final temperature of carbonization. The DH was 10.89 MPa for charcoal specimens produced at 300 C, 3.05 MPa for charcoal specimens produced at 450 C, 3.44 MPa for charcoal specimens produced at 600 C and 4.59 MPa for charcoal specimens produced at 750 C. The DH variation of charcoal between VMs also decreases with the temperature of carbonization, suggesting a lower influence of the precursor wood. Controlling carbonization processes is more important than selecting VM, at least for the mechanical performance of charcoal in blast furnaces. This study can serve as a reference for the mechanical classification of charcoal quality in industries.

The steel industry - even without investing heavily in stupid seabird and bat grinders to make small amounts of electricity while requiring increasing reliance on the dangerous fossil fuel natural gas - currently consumes over one billion tons of coal based coke per year.

I personally don't endorse grinding up two billion tons of trees each year to make steel, but that's just me, since I seem to be in the minority, since I know that so called "renewable energy" not only hasn't worked and isn't working, but that it won't work.

No one now living will ever see an atmospheric carbon dioxide concentration lower than 400 ppm again, mostly because left and right, we are invested in lying to ourselves.

I believe that carbon for steel making can be (as in "technically feasible" as opposed to "politically feasible" ) derived from the thermochemical reduction of carbon dioxide to the monoxide, and, to the extent it may prove necessary, disproportionation of carbon monoxide into carbon powder and carbon dioxide (which will be recycled) using Boudouard chemistry.

To the extent that said carbon dioxide is removed from the atmosphere (via seawater) and to the extent steel has a carbon content, this is effectively sequestered carbon.

The heat to drive this reaction can only come from nuclear energy in a clean world, as opposed to the delusional world in which we live in which nuclear energy is demonized by people who can't think and who thrive on fear and ignorance.

Have a nice day tomorrow.

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Reply Temperature Dependence of Biochar Hardness, a Factor in Displacing Coal Based Coke in Steel Making. (Original post)
NNadir Sep 2018 OP
Uncle Joe Sep 2018 #1
NNadir Sep 2018 #2

Response to NNadir (Original post)

Mon Sep 24, 2018, 10:33 PM

1. Can hemp be used as a substitute for wood?

Thanks for the thread NNadir.

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Response to Uncle Joe (Reply #1)

Mon Sep 24, 2018, 11:48 PM

2. For perspective, all the straw in China amounts to only about 600 million tons.

Controlling Air Pollution from Straw Burning in China Calls for Efficient Recycling (Li et al Environ. Sci. Technol., 2012, 46 (15), pp 79347936)

Steel requires a billion tons of carbon at current production levels, and, I note that straw is only fractionally carbon.

It is difficult to imagine that a non-food crop of any kind could find enough land area without inducing starvation. Not only that, considerable energy is required to collect and process grain never mind hemp or any other fast growing plant.

It is generally reported that photosynthesis on the entire planet captures about 100 billion tons of carbon dioxide per year, while the dangerous fossil fuel industry releases about 1/3 that quantity.

To the extent that carbon dioxide can be captured by photosynthesis, probably the most viable approach would be to use algae, which grows faster than land plants and takes up more carbon - this is an issue in eutrophication - but even this has an energy cost connected with dewatering. Since dewatering can be addressed by waste heat, or better yet, by supercritical water oxidation, this may be a lower hanging fruit that even straw, which will always be far more available than plants such as hemp grown for putative fuel, fiber or other purposes.

Again, from my perspective, thermochemical carbon dioxide splitting has a high energy to mass ratio when the heat source is nuclear, and is likely to have much lower environmental impact. To the extent carbon dioxide is obtained by reforming algae, this might be useful, but personally I think we will need direct carbon dioxide capture at this point, which is only remotely conceivable from the direct processing of seawater in supercritical settings. (This would have the benefit of rapid desalination as a side product.)

This is not to say that nuclear is risk free - clearly it isn't - but it is lower risk than all of its alternatives, which in a sensible world, as opposed to the one we live in, would be enough.

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