http://www.lifasa.com/
http://www.cydesa.com/esp/home.asp
15 d’abr. 2016
empreses catalanes que fabriquen condensadors
Investigadors de l'EPSEM utilitzen bacteris per recuperar els metalls dels telèfons mòbils en desús i reutilitzar-los
http://www.upc.edu/saladepremsa/al-dia/mes-noticies/investigadors-de-lepsem-utilitzen-bacteris-per-recuperar-els-metalls-dels-telefons-mobils-en-desus-i-reutilitzar-los-2
Investigadors de l'EPSEM utilitzen bacteris per recuperar els metalls dels telèfons mòbils en desús i reutilitzar-los
Un equip d’investigadors del Departament d’Enginyeria Minera, Industrial i TIC de la Universitat Politècnica de Catalunya (UPC) aposten per la biolixiviació com a tècnica potencial en la recuperació de metalls procedents dels residus electrònics dels telèfons mòbils. La tècnica es podria adaptar fàcilment a altres tipus de deixalles electròniques com ara televisors, ordinadors i neveres.
11/04/2016
Microorganismes que s’alimenten de la ferralla que hi ha a les plaques electròniques dels telèfons mòbils, per eliminar allò que no serveix i reciclar els metalls que es poden recuperar. Aquest fenomen físic, la biolixiviació, és l’objecte de recerca d’un grup d’investigadors delDepartament d’Enginyeria Minera, Industrial i TIC de la Universitat Politècnica de Catalunya (UPC), ubicat a l’Escola Politècnica Superior de Manresa (EPSEM), i encapçalat per Antonio David Dorado, Montserrat Solé i Xavier Gamisans.
En el procés, es posen en contacte deixalles electròniques que contenen metalls d’interès com ara el coure, l’or, el crom, el zinc, el níquel i l’alumini, entre d’altres, amb bacteris ferroxidants per aconseguir extreure’ls i donar un nou ús. En comptes d’atacar químicament els residus, s’aprofita la capacitat d’oxidar que tenen determinats microorganismes regenerant els agents responsables de l’extracció i reduint la utilització de reactius i d’altes temperatures.
Aquesta tècnica s’ha començat a posar en marxa amb plaques de circuit imprès de mòbils, però es podria fàcilment adaptar a altres tipus de deixalles electròniques com ara televisors, ordinadors o neveres, segons els experts.
L’espècie Acidithiobacillus ferrooxidans, microorganisme que creix en condicions molt adverses i difícil de trobar, és la més utilitzada i es troba a la natura, en espais com ara les aigües residuals urbanes de les depuradores. Els investigadors prenen mostres d’aquests entorns i les tracten al laboratori en les condicions òptimes per a què tan sols sobrevisqui aquesta espècie i es regeneri. Actualment també s’investiga amb altres microorganismes i comunitats que també estan donant bons resultats en un temps raonable.
Els microorganismes permeten extreure del residu allò que encara es pot aprofitar i que, en cas de no extreure’s, podria perjudicar l’entorn on aquest queda dipositat, contaminant l’aigua i el sòl. Amb aquesta tècnica es redueix la necessitat d’explotar recursos naturals per obtenir la gran quantitat de metalls, com ara el coure, que requereix actualment la tecnologia electrònica.
Els resultats de la investigació revelen que, en determinades condicions, l’acció dels microorganismes pot incrementar en un 30% la quantitat de metall recuperat i, d’aquesta manera, es pot recuperar el 99% del residu. La recuperació del metall procedent del residu és més rentable que la pròpia extracció del recurs natural original, ja que en aquestes deixalles la concentració és major que en les menes minerals, al mateix temps que es gestiona un residu molt problemàtic si no se’n fa un bon tractament.
En aquest punt de la recerca, els investigadors estan cercant en quines condicions es pot potenciar el procés d’extracció per a què sigui viable des del punt de vista industrial.
En el procés, es posen en contacte deixalles electròniques que contenen metalls d’interès com ara el coure, l’or, el crom, el zinc, el níquel i l’alumini, entre d’altres, amb bacteris ferroxidants per aconseguir extreure’ls i donar un nou ús. En comptes d’atacar químicament els residus, s’aprofita la capacitat d’oxidar que tenen determinats microorganismes regenerant els agents responsables de l’extracció i reduint la utilització de reactius i d’altes temperatures.
Aquesta tècnica s’ha començat a posar en marxa amb plaques de circuit imprès de mòbils, però es podria fàcilment adaptar a altres tipus de deixalles electròniques com ara televisors, ordinadors o neveres, segons els experts.
Menys contaminant i més econòmic
El procés és menys contaminant i més econòmic que els que s’utilitzen avui en dia i, a més, pot ser aplicat quan les baixes concentracions de metalls fan que les tècniques convencionals no siguin viables. Per a què funcioni, cal controlar les condicions que afecten a l’activitat dels microorganismes, com el pH, la temperatura o les concentracions de sals. Com a resultat del procés, el metall queda dissolt i, mitjançant un procés de separació, es recupera per ser utilitzat de nou en la construcció de plaques electròniques, entre altres aplicacions.L’espècie Acidithiobacillus ferrooxidans, microorganisme que creix en condicions molt adverses i difícil de trobar, és la més utilitzada i es troba a la natura, en espais com ara les aigües residuals urbanes de les depuradores. Els investigadors prenen mostres d’aquests entorns i les tracten al laboratori en les condicions òptimes per a què tan sols sobrevisqui aquesta espècie i es regeneri. Actualment també s’investiga amb altres microorganismes i comunitats que també estan donant bons resultats en un temps raonable.
Els microorganismes permeten extreure del residu allò que encara es pot aprofitar i que, en cas de no extreure’s, podria perjudicar l’entorn on aquest queda dipositat, contaminant l’aigua i el sòl. Amb aquesta tècnica es redueix la necessitat d’explotar recursos naturals per obtenir la gran quantitat de metalls, com ara el coure, que requereix actualment la tecnologia electrònica.
Els resultats de la investigació revelen que, en determinades condicions, l’acció dels microorganismes pot incrementar en un 30% la quantitat de metall recuperat i, d’aquesta manera, es pot recuperar el 99% del residu. La recuperació del metall procedent del residu és més rentable que la pròpia extracció del recurs natural original, ja que en aquestes deixalles la concentració és major que en les menes minerals, al mateix temps que es gestiona un residu molt problemàtic si no se’n fa un bon tractament.
En aquest punt de la recerca, els investigadors estan cercant en quines condicions es pot potenciar el procés d’extracció per a què sigui viable des del punt de vista industrial.
7 d’abr. 2016
6 d’abr. 2016
Tantalum is the most important element you've never heard of
You have likely never paid much attention to tantalum when you've gazed at the periodic table. It sits there, in the middle of a sea of transition metals, kind of out of the way and in the corner.
And yet, tantalum is increasingly important in the 21st Century, because it plays a large role in making personal electronic devices smaller, and it naturally fights corrosion. Along with the increased demand for tantalum comes a human price, as tantalum resources funded portions of the Second Congo War, the bloodiest conflict since World War II.
Corrosion-proof
Tantalum has the atomic number 73, snuggling the element between hafnium, niobium, and tungsten in the transition metal section of the periodic table. Discovered in the 19th Century, tantalum is named for Tantalus, a figure from Greek Mythology, who found himself doomed to spend eternity in a Saw-like torture scheme after death. An unknown force required Tantalus to stand in knee deep water, with delicious fruit handing overhead and just out of reach. The name refers to tantalum's own ability to be submerged in substances without being quenched.
In fact, tantalum's unusual characteristics led to its increased use in the late 20th and 21st Century. The element is extremely stable at temperatures lower than 150 degrees Celsius, and needs exposure to hydrofluoric acid, one of the nastier acids out there, to cause corrosion. This protection from corrosion is due to a natural protective layer created by oxides of tantalum on the surface of the the metal; making the element a perfect match for use in structures exposed to the the elements, like bridges and water tanks.
21st Century uses
Tantalum's primary 21st Century use comes in the creation of capacitors. Tantalum capacitors have an extremely high capacitance packed in a small volume — perfect for shrinking our electronic devices, or making additional room in them for larger processors or speakers. Tantalum is found in cell phones, dvd players, laptops, hard drives, and the PS3 — essentially almost any piece of home or industrial electronic equipment.
Tantalum's primary 21st Century use comes in the creation of capacitors. Tantalum capacitors have an extremely high capacitance packed in a small volume — perfect for shrinking our electronic devices, or making additional room in them for larger processors or speakers. Tantalum is found in cell phones, dvd players, laptops, hard drives, and the PS3 — essentially almost any piece of home or industrial electronic equipment.
Tantalum is also used to create surface acoustic wave filters, devices used in cell phones and televisions to improve audio quality. The average cell phone has about 40 milligrams of tantalum inside — not a considerable amount, but one that adds up quickly thanks to the millions and millions of cell phones in use.
Tantalum capacitors experience an extremely low failure rate, making them perfect for use in medical equipment, including hearing aids and devices that you don't want to randomly fail, like pacemakers. Tantalum is not harmed by bodily fluids, and does not irritate the flesh of the implantee, making it a perfect metal from which to create hip, knee, and other orthopedic implants.
How to Mine It
Tantalum is rarely found in its elemental form — the element is often found with niobium and the radioactive elements thorium and uranium, and industrial processes are required to extract pure tantalum. South American and Australia account for over two-thirds of the world's tantalum production, with a single mine in Brazil accounting for 20% of the world's annual supply.
Tantalum is rarely found in its elemental form — the element is often found with niobium and the radioactive elements thorium and uranium, and industrial processes are required to extract pure tantalum. South American and Australia account for over two-thirds of the world's tantalum production, with a single mine in Brazil accounting for 20% of the world's annual supply.
Increased use of tantalum in electronic devices has increased the cost of capacitor-grade tantalum over the past decade, with the refined form currently hovering around $300 a pound, while lower grade forms routinely sell for $100+ a pound.
Funding a civil war
"Coltan" is another name for columbite-tantalite, an ore containing a mix of niobium and tantalum. As we discussed yesterday, the Democratic Republic of the Congo (formerly Zaire) is extremely rich in coltan reserves, with rebels mining and then selling coltan to finance the civil war, with the majority of illegally mined coltan sold to China. The Second Congo War has claimed over 5.4 million lives, the bloodiest single conflict since World War II.
"Coltan" is another name for columbite-tantalite, an ore containing a mix of niobium and tantalum. As we discussed yesterday, the Democratic Republic of the Congo (formerly Zaire) is extremely rich in coltan reserves, with rebels mining and then selling coltan to finance the civil war, with the majority of illegally mined coltan sold to China. The Second Congo War has claimed over 5.4 million lives, the bloodiest single conflict since World War II.
The Kahuzi-Biega National Park and the Okapi Wildlife Reserve are extremely fertile sources of coltan, with mining activities driving out endangered gorillas in these protected areas. Mining coltan in the Congo also brings along another problem — due to the distance from home or camps, miners often kill and eat gorillas they come across in order to survive, further endangering the animals.
Locals also seek out coltan, well aware of the financial gains lying in the surrounding area as they sift for the rock in riverbeds and remove leftover pieces from abandoned mines. One-third of children in the Congo quit school to mine for coltan, which has a negative impact on the region for generations.
Individuals receive around ten dollars for a pound of unprocessed coltan, a good deal of money for those looking for a way to feed their families. Not the healthiest or safest way to make a living — but one that will persist as long as demand for tantalum is high and the price of life is low.
30 de març 2016
Do companies care about designing with conflict free components?
Some sources of information:
http://www.enoughproject.org/files/CorporateRankings2012.pdf
Apple:
http://images.apple.com/supplier-responsibility/pdf/Apple_Progress_Report_2015.pdf
Intel:
Tantalum
Tantalum is rarely used in elemental form.
Tantalum nitride (TaN) is often used as a resistor material in thin-film
networks for microwave hybrids (on alumina) as well as MMICs (on GaAs), due to
its high resistivity and stability over time and temperature. Tantalum
pentoxide (and other oxides) have been used as capacitor dielectrics in
electrolytic capacitors.
______________________________________________________
Jun 18, 2015 ... Resesarchers believe that graphene
could replace tantalum nitride within two chip generations.
The tantalum-nitride sheathing that is currently
used on copper wires in chips serves two functions. One is to help conduct
electricity and the other is to isolate the copper from the silicon on the
chip. Unlike the outer sheathing used in household copper wires, where the
wrapping prevents the wires from electrocuting us, the tantalum nitride ensures
that copper atoms do not contaminate the silicon transistors.
60% percent
of tantalum used in the U.S. is used in
capacitors.
Tantalum: uses
The
following uses for tantalum are gathered from a
number of sources as well as from anecdotal comments. I'd be delighted to
receive corrections as well as additional referenced uses (please use the feedback
mechanism to add uses).
Tantalum
metal has a number of important uses. It is used to make steels with desirable
properties such as high melting point, high strength, good ductility. These
find use in aircraft and missile manufacture. It is very inert and so useful in
the chemical and nuclear industries to line reactors. Tantalum wires were those
used first for light bulbs (now tungsten is preferred). The metal is immune to
body liquids and the body tolerates the metal well. Therefore, tantalum has
widespread use for surgical use. For instance, it can be used in sutures and as
cranial repair plates. The metal is used in the electronics industry for
capacitors.
The oxide is used to make
special glass with a high index of refraction for camera lenses.
Tantalum
Tantalum is a shiny, silvery metal which is soft when is pure. It
is almost immune to chemical attack at temperatures below 150 C . Tantalum is virtually
resistant to corrosion due to an oxide film on its surface.
Applications
Tantalum finds use in four areas: high-temperature applications,
such as aircraft engines; electrical devices, such as capacitors; sirurgical
impants and handling corrosive chemicals. It is rarely used as an alloying
agent because it tends to make metals brittle. Tantalum resist corrosion and is
almost impervious to chemical attack, for this reason it has been employed in chemical
industry, e.g. for heat exchanger in boilers where strong acids are vaporized.
Tantalum in the environment
Because tantalum oxide is very insoluble, there is almost no
tantalum to be found in natural waters. Few attemps have been made to measure
its level in soils, revealing a range from 0.1 to 3 ppm. Only tiny amounts of
tantalum are taken by plants: the amount in vegetation rarely exceeds 5 ppb.
The chief tantalum ores are tantalite, which also contains iron,
manganese and niobium, and samarskite, which contains seven metals. Another ore
which contains tantalum and niobium is pyrochlore. The main mining areas are
Thailandia, Australia, Congo, Brazil, Portigal and Canada. The demand of
tantalum is about 2300 tonnes a year. No assessment of total reserves of
extractable metal have been reliably calculated.
The primary use of tantalum metal is in making capacitors. A
capacitor is an electrical device similar to a battery. It can be

Tantalum
alloys are used to make artificial joints, such as an artificial hip shaft
(left) and socket.
given an electrical charge, which it then stores
until needed. Capacitors are essential parts of nearly all electrical circuits. Semiconductor circuits, like those used in transistors, require
tiny capacitors the size of grains of rice. Tantalum is one of the best metals
for this purpose. Different kinds of capacitors are made for many different
applications. They are used in military weapons systems, aircraft, space
vehicles, communication systems, computers, and medical applications. For
example, the smallest hearing aids are likely to have a tantalum capacitor.
Tantalum is also used in many different alloys. An alloy is made
by melting and mixing two or more metals. The mixture has properties different
from those of the individual metals. Tantalum alloys are used in laboratory
equipment, weights for very precise balances, fountain and ball point pen
points, and tools that have to operate at high speeds and temperatures.
Another application for tantalum alloys is in medical and dental
applications. The metal has no effect on body tissues. It is used in artificial
hips, knees, and other joints. Pins, screws, staples, and other devices used to
holds bones together are also made of tantalum alloys.
A few weeks ago I worked through the Altium
SMPS design course from FEDEVEL academy and that little project left me with an
unresolved question. Somehow I got the idea in the past few years that tantalum
capacitors are to be avoided, never really knowing why. Yet try to find a
330uF, 6.3V capacitor with ~4mOhm ESR and you’ll find that tantalum is
basically the only option. So I wanted to start a discussion about tantalum
caps with the main questions being:
- When and why to use tantalum capacitors?
- Why avoid using tantalum capacitors?
- Alternatives to tantalum capacitors with pros and cons.
I did some quick research already and here’s summary of what I’ve found so far
Why and when to use tantalum capacitors?
Tantalum is used to create small sized capacitors with ‘large’ capacitance. Compared to other materials the oxide layer can be quite thin. So for all applications where pcb space is limited (e.g. mobile phones) they are the to go to type of capacitor when ceramic doesn’t cut it anymore.
Also tantalum capacitors can be created with quite small ESR. This is why they are used a lot in (local) switched power supplies as bulk capacitor. Ceramics have even lower ESR, but in power supply regulators that might be too low for loop stability.
Why avoid using tantalum capacitors?
From what I can find these are the main reasons to avoid tantalum capacitors in your design:
Financial:
Tantalum capacitors are relatively expensive even when supply and demand are balanced. Not too long ago prices went sky high due to a shortage in raw materials.
Reliability:
There are numerous reports of tantalum capacitors spontaneously combusting. I haven’t read into this any further, but I take it some forum members can elaborate on this.
Moral:
Since some of the major tantalum ore (columbite-tantalite / coltan) mines are located in conflict zones (e.g. Democratic Republic of Congo) so one can argue that tantalum is a conflict mineral. I’m not sure though to what extent that still counts today as there are major mines elsewhere in the world too.
Tantalum is a heavy metal and as such toxic and not really well for the environment. I did find a paper by AVX that discussed ‘green’ tantalum technology though.
Alternatives to tantalum capacitors and pros and cons?
Niobium caps
Apart from being mentioned I haven’t been able to find useful information yet, apart from that there is more Niobium ore available which should make Niobium caps cheaper. On the other hand Coltan is also used for mining Niobium so maybe the conflict argument could apply here too?
(Wet) Aluminum Electrolytic caps (Elco)
Specific low-ESR Elcos can be used. Larger values, larger ripple current rating, larger voltage ratings are some benefits. I must admit though that I realized that I haven’t seen SMT Elcos a lot outside consumer gear. Did I miss something?
Polymer (Solid) Aluminum caps
Used as in- or output bypass caps in SMPSs. Larger values only available in small voltage ratings. I don’t know by how much these must be derated though. Please tune in if you know more about this kind of caps.
Monolytic Ceramic caps
Larger voltage ratings, smaller derating, and higher ripple current ratings are among its benefits compared to tantalum caps. Since the ESR is much lower a small external resistance may be needed for loop stability in SMPS designs.
Sources
Here is some of the info I found. There is a lot to be found, and you'd have sift to get the info you want too. I included the year of publishing when available, since a few years in our industry means lots of changes.
AVX. (n.d.). Comparison of Multilayer Ceramic and Tantalum Capacitors
AVX. (n.d.). “Green” Environmentally Friendly Technology For Tantalum And Niobium Oxide Capacitors
Digikey. (n.d.). Tantalum Alternative Solutions by Panasonic
EETimes. (2001). Tantalum capacitor options weighed
Kemet. (2008). Comparison of Ceramic and Tantalum Capacitors
NIC Components. (1999). Alternates to surface mount tantalum electrolytic capacitors
Wikipedia. (n.d.) Coltan
Related Threads on the EEVblog
Tantalum caps
why we tend to not use electrolytics for decoupling to gnd?
Output capacitor of a DC/DC converter
- When and why to use tantalum capacitors?
- Why avoid using tantalum capacitors?
- Alternatives to tantalum capacitors with pros and cons.
I did some quick research already and here’s summary of what I’ve found so far
Why and when to use tantalum capacitors?
Tantalum is used to create small sized capacitors with ‘large’ capacitance. Compared to other materials the oxide layer can be quite thin. So for all applications where pcb space is limited (e.g. mobile phones) they are the to go to type of capacitor when ceramic doesn’t cut it anymore.
Also tantalum capacitors can be created with quite small ESR. This is why they are used a lot in (local) switched power supplies as bulk capacitor. Ceramics have even lower ESR, but in power supply regulators that might be too low for loop stability.
Why avoid using tantalum capacitors?
From what I can find these are the main reasons to avoid tantalum capacitors in your design:
Financial:
Tantalum capacitors are relatively expensive even when supply and demand are balanced. Not too long ago prices went sky high due to a shortage in raw materials.
Reliability:
There are numerous reports of tantalum capacitors spontaneously combusting. I haven’t read into this any further, but I take it some forum members can elaborate on this.
Moral:
Since some of the major tantalum ore (columbite-tantalite / coltan) mines are located in conflict zones (e.g. Democratic Republic of Congo) so one can argue that tantalum is a conflict mineral. I’m not sure though to what extent that still counts today as there are major mines elsewhere in the world too.
Tantalum is a heavy metal and as such toxic and not really well for the environment. I did find a paper by AVX that discussed ‘green’ tantalum technology though.
Alternatives to tantalum capacitors and pros and cons?
Niobium caps
Apart from being mentioned I haven’t been able to find useful information yet, apart from that there is more Niobium ore available which should make Niobium caps cheaper. On the other hand Coltan is also used for mining Niobium so maybe the conflict argument could apply here too?
(Wet) Aluminum Electrolytic caps (Elco)
Specific low-ESR Elcos can be used. Larger values, larger ripple current rating, larger voltage ratings are some benefits. I must admit though that I realized that I haven’t seen SMT Elcos a lot outside consumer gear. Did I miss something?
Polymer (Solid) Aluminum caps
Used as in- or output bypass caps in SMPSs. Larger values only available in small voltage ratings. I don’t know by how much these must be derated though. Please tune in if you know more about this kind of caps.
Monolytic Ceramic caps
Larger voltage ratings, smaller derating, and higher ripple current ratings are among its benefits compared to tantalum caps. Since the ESR is much lower a small external resistance may be needed for loop stability in SMPS designs.
Sources
Here is some of the info I found. There is a lot to be found, and you'd have sift to get the info you want too. I included the year of publishing when available, since a few years in our industry means lots of changes.
AVX. (n.d.). Comparison of Multilayer Ceramic and Tantalum Capacitors
AVX. (n.d.). “Green” Environmentally Friendly Technology For Tantalum And Niobium Oxide Capacitors
Digikey. (n.d.). Tantalum Alternative Solutions by Panasonic
EETimes. (2001). Tantalum capacitor options weighed
Kemet. (2008). Comparison of Ceramic and Tantalum Capacitors
NIC Components. (1999). Alternates to surface mount tantalum electrolytic capacitors
Wikipedia. (n.d.) Coltan
Related Threads on the EEVblog
Tantalum caps
why we tend to not use electrolytics for decoupling to gnd?
Output capacitor of a DC/DC converter
Tantalum capacitor options weighed
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