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The recycling society: Steel (09/02/22 19:20:52) Reply
    Disclosure: I am not a metallurgist.

    To preserve limited resources, recycling of material is necessary. A thousand more years of collecting unrecyclable material in landfill would be a severe, perhaps unbearable, burden.

    We do already recycle gold, silver, copper and aluminium. Some losses are inevitable.
    I'd concentrate on steel, which is a complex material

    https://en.wikipedia.org/wiki/Alloy_steel
    https://en.wikipedia.org/wiki/Stainless_steel
    https://en.wikipedia.org/wiki/High-strength_low-alloy_steel
    https://en.wikipedia.org/wiki/Weathering_steel

    For successful recycling to take place, there must be sufficient quantities available at the same time and place - and there must be a smelter equipped and qualified for the task. The quality of the material depends on the purity of the scrap metal available. The real expert recycler would know beforehand what the product would be like, and what additional components to add.

    Removing components looks difficult if not impossible. So - in 1000 years maybe all steel will be stainless multi-alloyed . Shall I guess: One decree more complexity every 50 years?

    Separating out the different elements seems like a very expensive task. So perhaps it is time to mandate detailed marking of all steel object and fund research into simplified and effective recycling of alloyed steels?
e
One-way streets lead to perdition (10/02/22 08:50:48) Reply
    When metallurgy is designed for performance of the product, recycling is no part of the planning. Stainless steel is really luxurious with all that chrome and nickel.

    How do we recycle worn-out adjustable wrenches - either carbon steel with or without manganese or molybdenum steel together with screwdrivers which may be tungsten steel or vanadium steel? How to conserve those precious additional metals?

    Now they either accumulate or are put into landfills or recycled into less precious steels (I suppose). I have no trust in the expertise of the management of scrapyards.

    There is an analogy:
    When some bacteria are treated with macrolide antibiotics, the protein synthesis process is broken off before completion, and the unfinished pre-proteins accumulate because the recycling process cannot cope. In the end there is no raw material available for synthesis of essential products - and eventually the bacterium dies.

    Recycling metals is hard. One way to go is simplifying the offerings. Another is accurate compulsory labelling. And yet another is more specialised recycling.
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Re: long live the aluminium  (11/02/22 22:42:11) Reply
    Well not sure about steel, but aluminium recycling is pretty neat and all parts can be recovered/reused. The salt to clean it, and the by-products to build roads.
    Maybe we need to move to materials that can be widely recyclable as Alu?
rf
Sand (12/02/22 19:48:27) Reply
    Building megacities requires gigatons of cement.

    "The total volume of cement production worldwide amounted to an estimated 4.1 billion tons in 2020. Back in 1995, the total global production of cement amounted to just 1.39 billion tons, which indicates the extent to which the construction industry has grown since then. "

    (https://www.statista.com/statistics/1087115/global-cement-production-volume/)

    I shudder at the thought of the number of gigatons of sand.

    I saw a TV program about sand collection from the river bed of the Niger. The sand was harvested by diving - in a river with hippopotami. The sand was t be used in Bamako.

    I've seen some of the environmental effects of sand and gravel mining in fjords close to me when the huge concrete platforms were built

    https://en.wikipedia.org/wiki/Condeep

    North of Stavanger there is plenty of moraine material

    https://en.wikipedia.org/wiki/Moraine

    and - critics say - the inhabitants of those small places sold the ground from under their own feet.

    Anyway - the carbon footprint of cement, and the environmental impact of removing sand and gravel: at some point in time they will need to be considered.
e
Re: Sand 3d printing (12/02/22 19:58:26) Reply
    https://youtu.be/ptUj8JRAYu8
rf
Re: Re: Sand 3d printing (23/02/22 21:06:29) Reply
    It shows the power of a 2 square meter Fresnel lens in the desert sun.

    But for recysling I would rather he used it on discarded glass wool that otherwise would have ended in a landfill. Destroying sand is what he did.

    In the area of our cabin_by_the_sea it is mandated that the original landscape must be recoverable when a building is removed. So there are limitations on the techniques permissible. Also, burning bonfires on bare rock is forbidden because it accelerates erosion.
e
Re: Re: long live the aluminium  (19/02/22 19:23:50) Reply
    Kaolin, the raw material for porcelain, is mainly aluminium silicate. So it could be a raw material. The chloride process would be the method of choice. But I think the cost of grinding up old toilets for the aluminium via the chloride process will be too expensive as long as large quantities of the clay are still available.
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The recycling society: Ceramics: Fillers. Isolation materials. Kitchenware. Toilets and washbasins. (11/02/22 19:26:20) Reply
    Pottery formed from clay and then fired are old technology. The ultimate quality, porcelain, is a sophisticated mix of select minerals (metal oxides and silicates) then fired.
    https://en.wikipedia.org/wiki/Porcelain

    Lots of material goes into toilets. They have a useful working life, then they are replaced. So: can they be recycled, so as to preserve the precious materials that go into them?

    https://www.thinkingsustainably.com/is-porcelain-recyclable/
    https://recyclenation.com/2015/02/how-to-recycle-ceramic-and-porcelain-tiles/

    The answer is no. Some can be recycled as ceramic tiles; some go into unqualified uses like roadbuilding (instead of stone), but most go into landfills.

    So - how long will the kaolin resources last with this one-way system?
e
Fluorine-containing textiles (13/02/22 13:41:09) Reply
    "Gore-Tex was co-invented by Wilbert L. Gore and Gore's son, Robert W. Gore.[1] In 1969, Bob Gore stretched heated rods of polytetrafluoroethylene (PTFE) and created expanded polytetrafluoroethylene (ePTFE). His discovery of the right conditions for stretching PTFE was a happy accident, born partly of frustration. Instead of slowly stretching the heated material, he applied a sudden, accelerating yank. The solid PTFE unexpectedly stretched about 800%, forming a microporous structure that was about 70% air.[1] It was introduced to the public under the trademark Gore-Tex." (Wikipedia)

    Polytetrafluoroethene is a wonderful material - with enormously valuable properties. Low-friction surfaces, water- and fat-repellant, lightweight, formable, chemically inert.
    https://en.wikipedia.org/wiki/Polytetrafluoroethylene

    But

    "Recycling: PTFE membranes, in contrast to technically equivalent alternatives in the laminate
    structures relevant to the textile industry, cannot yet be recycled in an ecologically and economically sensible way. As a result, they (and all materials permanently bonded to them, e.g. by lamination) represent barriers to the EU [9] and its Member States future objectives regarding recycling, recycled content, recyclability for the textile and footwear industry. They also represent high hazards in recycling streams not controlled by high level environmental standards, or through individual burning of garments and shoes in the open air. Therefore the contact of innocent third parties with highly toxic hydrofluoric acid cannot be excluded. [10]
    https://www.sympatex.com/wp-content/uploads/2021/04/report_PTFE_call_for_a_ban_April2021.pdf

    And - to emphasise: Hydrofluoric acid, which is a combustion product, is an extremely nasty substance.

    "Because of the ability of hydrofluoric acid to penetrate tissue, poisoning can occur readily through exposure of skin or eyes, or when inhaled or swallowed. Symptoms of exposure to hydrofluoric acid may not be immediately evident, and this can provide false reassurance to victims, causing them to delay medical treatment.[24] Despite having an irritating odor, HF may reach dangerous levels without an obvious odor.[5] HF interferes with nerve function, meaning that burns may not initially be painful. Accidental exposures can go unnoticed, delaying treatment and increasing the extent and seriousness of the injury.[24] Symptoms of HF exposure include irritation of the eyes, skin, nose, and throat, eye and skin burns, rhinitis, bronchitis, pulmonary edema (fluid buildup in the lungs), and bone damage.[25]"

    (Wikipedia)
    I think it is somewhat inaccurate, but not with regard to the nastiness of the substance. Burning GoreTex garments in a bonfire is not a responsible way of getting rid of old clothes.

    Even GoreTex has seen the warnings
    https://www.gore-tex.com/sites/default/files/assets/Gore%20Fabrics%20Responsibility%20Report%202017_EN_Final_20171208.pdf

    although not entirely convincing, specially because competitors have non-fluorinated products.
e
Re: Fluorine-containing textiles (15/02/22 17:04:14) Reply
    There is an international agreement about chlorofluorocarbons - the ozone layer destroyers.
    https://www.epa.gov/ozone-layer-protection/basic-ozone-layer-science
    Banning them led to recovery of the Antarctic ozone layer.
    https://www.nasa.gov/feature/goddard/2020nasa-data-aids-ozone-hole-s-journey-to-recovery

    So - although it will require a lot of work - don't ask me - I know, but will not tell in the open - there should be an international ban on large-scale fluorocarbon chemistry. Those resisting will have to make a case that 100 percent recycling is possible, and that accumulation in the biosphere is not dangerous.
e
Newer (re:O3) (15/02/22 17:35:08) Reply
    https://earthobservatory.nasa.gov/images/149010/substantial-antarctic-ozone-hole-in-2021
e
Fluorine in lithium batteries (16/02/22 10:25:40) Reply
    Fires in old lithium batteries are dangerous - not only because of the fire itself, but because of the presence of LiPF6 - lithium hexafluorophosphate.

    https://en.wikipedia.org/wiki/Lithium_hexafluorophosphate

    "The electrolyte fire will generate substantial amount of HCl, HF, CO, HCN, and potentially SO2 and H2S, depending on the battery technology and the electrolyte technology."

    https://solarfiresystems.com/news/suppressing-lithium-ion-battery-fires

    One can never be sure of the actual 0battery technology when there is a battery fire. Always have in mind that HF is likely to be in the smoke.

    Remaining charge in batteries may be a fire risk too, if batteries are opened or damaged accidentally.

    This means that dismembering of Li-batteries for recycling is for professionals only - working in adequately secured facilities.

    There are articles about it in the open. But the big folks are already there.
e
Perfluorinated lubricants (20/02/22 10:30:39) Reply
    I saw onw yesterday: lubricant for wheel axle ball bearings of bicycles. For skiers there are gliders and waxes of varying hardness for grip regulation. The ski systems are now banned, but they do give an advantage to cheaters. Cheating can only be exposed by means of analysis, and I cannot imagine that analysis is possible without heavy equipment - read mass spectrometers. So cheating will be safe for a while in spite of the ban, I suppose.
e
The recycling society: Synthetic polymers (13/03/22 19:20:18) Reply
    Synthetic polymers are oil-based and should be treated as a precious and nonrenewable resource. This will need planning. Firstly, the number of chemistries available for the consumer should be kept at a minimum. Only then will it be possible to collect large enough and pure enough quantities for recycling to be practical and economical. Each chemistry must be easily identifiable, for example by RF tags or fluorescent labelling - barcodes, few-letter-ID codes. Then the number of permissible dyes must be kept low, too. Decorations could be done on paper, not on the plastic.

    If we can keep lawyers and politicians out of the decision loop, this could be done easily, within a few months. Typically a job for the EU commission.

    Make it soon!
e
Polyester (PET) hydrolases (23/05/22 16:34:21) Reply
    In a recent press release from a German university (Leipzig) we are informed of a specially active polyester hydrolase found in a bacterium from a city dump. That's good news: single-use food containers and old clothes can now be split into the monomers: terephtalic acid (p-benzenedicarboxylic acid) and ethylene glycol and reused - if the finding results in effective and cost-effective protocols. I see then a succession of processes: First dissolving and washing out the PET from an unsorted mix, then a second specific method, perhaps enzymatic oxidation via a P450-enzyme of polyethene and polypropylene yielding a much more diverse mix of small molecules.

    "Low-density polyethylene is the most abundant plastic waste discarded in landfills in the form of plastic bags (69.13%). LDPE is mostly amorphous, with short branches (10–30 CH3 per 1,000 carbon atoms) and composed of one or more comonomers, such as 1-butene, 1-hexene, and 1-octene. This branching system makes LDPE chains more accessible and the tertiary carbon atoms at the branch sites more susceptible to attack. The physical arrangement of the polymer chains in LDPE and a lower content of vinylidene defects, which have been shown to be directly correlated with oxidization of the polymer makes it more biodegradable than High-density polyethylene (HDPE). Further, the molar mass of HPDE is much higher, possibly making it more difficult for microorganisms and their oxidizing enzymes to access the polymer chains (Sudhakar et al., 2008; Fontanella et al., 2010). Few comparison studies have been made on the biodegradability of various pre-treated polyethylene materials, including, LDPE, HDPE, and linear low-density polyethylene (LLDPE) films of different thickness by Rhodococcus rhodochrous, which is one of the most efficient bacteria for PE biodegradation (Fontanella et al., 2010). Structural variations in PE polymers formed during polymerization and subsequent processing, such as unsaturated carbon–carbon double bonds, carbonyl groups, and hydroperoxide groups (Ojeda et al., 2011) have been shown to be consumed first by the bacteria resulting in rapid growth.

    Many of the species known to degrade PE are capable of hydrolyzing and metabolize linear n-alkanes, like paraffin molecules (e.g., C44H90, Mw 618) (Haines and Alexander, 1974). Alkane hydroxylases (AHs) are the key enzymes involved in aerobic degradation of alkanes by bacteria. The first step involves hydroxylation of C-C bonds to release primary or secondary alcohols, which are oxidized to ketones or aldehydes, and subsequently to hydrophilic carboxylic acids (Alvarez, 2003; Watanabe et al., 2003). Microbial oxidation reduces the number of carbonyl-groups due to the formation of carboxylic acids. "

    "Rather, both the insect digestive system and the larval gut microbiome are required to achieve accelerated biodegradation of the PE polymers.

    In recent years, biodegradation of other petro-plastics, like PE and PS, insect larvae such as Yellow Mealworms (Tenebrio molitor) (Billen et al., 2020), Dark Mealworms (Tenebrio obscurus) (Brandon et al., 2018; Peng et al., 2019), Superworms (Zophobas atratus) (Peng et al., 2020b), Lesser Waxworms (Achroia Grisella) (Kundungal et al., 2019), and by snails (Achatina fulita) (Song et al., 2020), have been reported."

    (https://www.frontiersin.org/articles/10.3389/fmicb.2020.580709/full)

    A lot of work needs to be done to obtain high enough capacity (rapid degradation). The patents, I guess, will have to be on the reactors. So there will be competition.
e
The recycling society: Sulfuric acid (23/05/22 15:30:36) Reply
    Sulfuric acid used to be a byproduct of metal smelting: Copper, zinc, lead (and silver) are mined as sulfides. Burning off the sulfur is IIRC the first step. The resulting sulfur dioxide is raw material for sulfuric acid, which is a catalyst as well as a raw material.

    "Globally, more sulfuric acid (H2SO4) is consumed than any other industrial chemical. In the U.S. alone, over 35 million tons of sulfuric acid are produced every year — roughly two and a half times the amount of propylene, which is second on the list.

    More than half of the sulfuric acid in North America is consumed by the fertilizer industry. A large portion of the remaining supply is used for manufacturing a wide range of materials, such as glue, preservatives, cosmetics, dyes, pulp and paper, steel, pharmaceuticals, explosives, batteries, etc."

    (https://blog.veolianorthamerica.com/how-is-sulfuric-acid-regenerated)

    (thanks to oeg for the tip)
e
The recycling society: Zinc (24/05/22 15:29:31) Reply
    Protection of steel

    "When a hot-dip galvanized object leaves the zinc bath the surface of the object is immediately attacked by oxygen in the air. The resultant oxide layer has very little ability to protect against corrosion. However, water and carbon dioxide in the air quickly change the oxide layer to zinc carbonates. These give a sealed layer with very good adhesion. Since the carbonates have very low solubility in water they give excellent protection to the surface of the zinc coating. The original shiny surface with a metallic lustre disappears to be replaced by matt, light grey colour (fig.1)."

    (https://nordicgalvanizers.com/corrosion-of-zinc-coatings/)

    Recycling happens. But is it enough?

    "The uses of zinc have not significantly changed over time; however, refined zinc consumption has more than doubled in the last 40 years to over 13 million tonnes annually. The majority of this growth has occurred in applications with long effective lifetimes, such as galvanizing, where these products may stay in service up to 100 years."

    https://www.zink.de/wp-content/uploads/ALTE_TYPO3_SEITE/D_O_K_U_M_E_N_T_E/Broschueren/IZA_Broschueren/IZA_Closing_the_Loop_new.pdf

    "Reserves of zinc – like those of any natural resource – are not a fixed amount stored in nature. Reserves are determined by geology and the interaction of economics, technology and politics. The term Reserves denotes the portion of resources that has been mapped and measured and which may be used, now or in the future."

    https://www.galvanizing.org.uk/sustainable-construction/zinc-is-sustainable/zinc-recycling/
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