Flat screen tv recycling: Best Buy customers are part of the solution to e-waste

It is widely known that the kinescope is made of glass, the chemical composition of which varies depending on the functions of the elements of the kinescope. One of the main functions of glass is protection from x-rays. To do this, about 34 wt.% PbO is usually injected into the glass of the electron gun. A somewhat smaller amount of lead oxide contains a kinescope cone (22 wt.% PbO). In the case of a kinescope screen, its glass is specially made thicker to absorb dangerous X-rays. In addition, this glass must have good optical properties, so it is made from barium-strontium glass (it absorbs X-rays about one and a half times worse than lead glass). Note that in the screens of color TVs released before 19For 95 years, glass containing up to 5 wt.% PbO was used. However, thanks to the efforts of the German Central Association of the Electrical and Electronics Industry (ZVEI) to increase the volume of recycling of kinescopes, since 1996, most manufacturers have completely switched to the production of screens without the use of lead oxide. American manufacturers Corning and Corning Asahi Video only did not follow this example (Thompson RCA moved in 1998).

In black-and-white television sets, the screen and the kinescope cone are made from the same type of glass, which usually contains up to 4 wt.% PbO. This difference in the chemical composition of glasses of different types of TVs is due to more powerful X-ray radiation in color TVs due to an increase in the accelerating voltage to 20–30 kV versus 10–20 kV for a black and white TV. The average chemical composition of the kinescope glasses is given in the table below (depending on the manufacturer, the composition of the glass may vary somewhat).

As the reader has probably already guessed, the main environmental hazard is lead oxide, which is part of the kinescope glass. The amount of lead oxide in one kinescope depends on its size and can vary from 0.5 to 2.9 kg with an increase in its measurements from 13 to 32 inches, respectively.

The content of lead(II) oxide depending on the size of the kinescope

A feature of these glasses is that lead ions are relatively easy to leach out of the glass and enter the environment. For example, with improper disposal of a kinescope, leaching of lead ions can occur under the action of organic acids, which are formed at a landfill for household waste. Of all the lead-containing kinescope components, glass cement is the most easily leached.
Lead, like its compounds, is a toxicant with a pronounced cumulative effect, causing changes in the nervous system, blood and blood vessels. This circumstance implies the need for proper disposal of kinescopes by burying them in special landfills or recycling them.

Let’s consider the existing ways of utilization of kinescopes.
As a rule, the recycling process begins with the manual dismantling of televisions or computer monitors. In this operation, the case, printed circuit boards, speakers, wires, protective metal casing, deflection system and electron gun are dismantled. Also, for safety reasons, during this operation, a vacuum is released from the kinescope by making a hole in the place of the high-voltage output or through the neck of the electron gun. The protective iron clamp over the connection of the kinescope cone with the screen is also cut off. All these components are sent for further processing. As a result, only a kinescope remains, which must be divided into a cone and a screen due to their different chemical composition, which is important for their subsequent disposal.

In practice, the separation of the cone and shield is most often done with a diamond saw, hot nichrome wire or laser. After that, an internal magnetic screen with a mask is removed from the cut kinescope, and the screen itself is sent to a chamber in which a phosphor is collected with a vacuum cleaner (buried at a special landfill). Thus, two types of glass are obtained at the output – lead and barium-strontium.

This process is shown in the video below.

There is also a slightly different way of separating lead and barium-strontium glasses. This method consists of the following technological operations: kinescope crushing, magnetic fraction isolation, mechanical removal of coatings, glass washing with water, drying, and, finally, separation into lead, barium-strontium and mixed glass using special analyzers (X-ray fluorescent or ultraviolet) and air guns . Note that in this technology, water is used in a closed cycle, and the amount of waste is 0.5% (glass dust, phosphor, coatings). This method of glass separation is used by Swissglas AG (Switzerland), RTG GmbH (Germany), SIMS (Great Britain).

Now let’s move on to the most important issue – the disposal of lead and barium-strontium glass. Until recently, these glasses were mainly sent to factories for the manufacture of new kinescopes. However, with the advent of liquid crystal and plasma displays, the production of kinescopes ceased, which made this method of processing practically irrelevant. However, there are three enterprises in China (Shaanxi IRICO Electronic Glass, Henan AnCai Hi-Tech and Henan AnFei Electronic Glass) that can use up to 100 thousand tons of glass per year, which is only a small part of the total (5.2 million tons according to a report by Qinghua University).

It should be noted that barium-strontium glass has found application in the production of building materials due to the low leaching of barium and strontium ions, the concentration of which does not exceed the permissible limits. Therefore, further we will focus only on the disposal of lead glass.

Today, the single most common method of processing lead glass is to use it as a recyclable material to produce lead. For this, metallurgical melting furnaces for lead are used, in which the flux is partially replaced by lead glass. However, the number of furnaces that use lead glass in their technological process is rather small in the whole world. For example, Doe Run (USA), Xstrata and Teck Cominco (Canada), Boliden Rönnskär Smelter (Sweden), Metallo-Chimique (Belgium).

Due to the small number of furnaces and the high cost of transporting recyclable materials to them, it was easier to send lead glass to a landfill. However, some e-waste companies have chosen a different path.
For example, to solve this problem, SWEEEP Kuusakoski Ltd. (Great Britain) together with Nulife Glass, the University of Sheffield and Aalto University developed and put into operation on November 30, 2012 a furnace for the production of lead from glass. The furnace is heated by electricity, and the raw material used is pre-crushed and mixed with a reducing agent lead glass (crumb up to 3 mm in size). After the recovery process at 1200 ^o With the output, lead granules and glass are obtained. This furnace can process up to 10 tons of glass or up to 2,000 large TVs per day.

Report from the opening ceremony

Alternative methods for the disposal of lead glass have also been proposed. In general, they all boil down to the idea of ​​using glass for the manufacture of building materials (foam glass, for example) or as an additive in building materials such as brick, concrete, cement, decorative tiles, etc. Building materials with a high content of lead glass can be used to protect against x-ray radiation. It has also been suggested that lead glass be used in the ceramics industry to create glazes that are resistant to leaching.

The main disadvantage of building materials with lead glass additives is the decrease in their mechanical properties. In addition, the results of the leaching tests showed that the concentration of lead ions in most cases exceeds the permissible limits (according to American standards, the concentration of lead ions should not exceed 5 mg/l). We also note that in many countries the use of toxic substances in building materials is prohibited by law.

The above problem can be solved by special chemical treatment of glass, the essence of which is the preliminary leaching of lead. In this method, leaching is typically carried out with nitric acid for one hour, followed by washing and drying of the ground glass. Further, the leaching products are sent to a chemical plant for further processing, and the resulting glass chips can be used in building materials. This lead glass recycling method is used in Hong Kong.

In conclusion, it should be said that the problem of recycling old CRT TVs and monitors will be relevant for at least another decade. The situation with the solution of this problem can differ significantly in different countries of the world, which is primarily due to the lack or availability of technologies and processing enterprises, state support, and a recycling culture. In the CIS countries, as well as in Ukraine, the state of affairs in this regard can be said to be deplorable. Only in not many cases do kinescopes end up at special landfills, and one can only dream of their processing.

What to do with the old kinescope TV

August 16, 2020

CRT televisions have already outlived their lives. If you still have such a TV, then it is easier to sell or dispose of it.

Cathode ray tube televisions are almost out of use. From living rooms and bedrooms, they have long migrated to summer cottages, rented apartments, supply rooms and other places where it is a pity or not economically feasible to install a modern TV. However, more and more often, old equipment becomes completely useless, so it needs to be attached somewhere or thrown away. If you do not have a dacha where the old TV could still serve, then there are not so many other options.

Photo: Unplash

It should be noted that you can’t just throw away the TV. As well as other electronic devices, household appliances, light bulbs and batteries. All of them contain harmful substances that can harm the environment.

Recycling

Large retail chains often hold promotions with the acceptance of old equipment. You can bring old, and even faulty, equipment and get a discount on a new one. Also, if you bring a TV, you don’t necessarily need to buy a TV. There is a list of goods participating in the promotion, which includes a variety of equipment from smartphones to refrigerators. Please note that promotion rules may vary. Specify in advance what exactly you can get a discount on, what can be handed over and in what condition.

Some electronics retailers also have a “Recycling” service. Unlike a promotion, it is paid, so there is no benefit for the buyer. However, in this way you help to save nature. But in any case, it is better than taking out old equipment somewhere on your own. However, it is better to wait for the action.

In addition to retail chains, specialized companies also deal with recycling. There are quite a few of them, it is enough to drive in the search query “utilization of household appliances” or “export of household appliances”. Of course, few people are willing to pay for disposal, because it is much easier to take the equipment to the nearest garbage collection point.

Sale

A more troublesome, but often equally profitable way to get rid of an old TV is to sell it. A lot depends on the device itself. You won’t get much for a simple model. Sellers on ad sites ask for quite ridiculous money from 500 to 1000 rubles. It will still be more profitable to hand over the stock to an electronics store. A little more expensive you can sell a big-screen TV of a famous brand.

It is worth noting that there are a lot of offers. You will most likely have to wait before someone responds. In addition, you can try to give away TV for nothing. You won’t earn anything, but you won’t have to dispose of it.

But there are also really expensive models costing 15,000 rubles and more. You can argue for a long time who and why needs a TV for such an amount, but there are many such proposals. A quality CRT TV is great for standard-definition terrestrial television, and can be used with VCRs and older game consoles.

For viewing terrestrial TV and standard definition content, this TV is perfect. Expensive models not only have a contrasting and clear image, but also powerful built-in sound.

If the TV is an expensive brand, with additional video inputs, flat screen, 100 Hz, then it can be relatively expensive. Therefore, perhaps you should not rush to sell and set the minimum price, and even more so to hand over such a TV for recycling. Wait until a buyer shows up who really needs a quality CRT.

Special mention should be made of television sets that have a collection value. Of course, it is unlikely that something like this is just gathering dust in your apartment. However, vintage television receivers can cost a lot.