CN1188161A

CN1188161A - Method for non-toxic removing glass and ceramic to regenerate metal element

Info

Publication number: CN1188161A
Application number: CN97101715A
Authority: CN
Inventors: 路志清
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-01-11
Filing date: 1997-01-11
Publication date: 1998-07-22

Abstract

The present invention belongs to the field of chemical cleaning and metal element regeneration technology for regenerating metal element which is discarbed because of joining together with glass ceramics. It uses caustic alkali and other material capable of reacting with glass ceramics to produce soda-potash glass as solvent, heats to make reaction, and the temp. which can liquate solvent is used as lower limit of temp., and the temp. of working zone can be above 400 deg.C, and the phase transition temp. of metal element required to be recovered and the temp. changing geometrical form are used as high limit of the temp.. Said invention is non-toxic, free from contamination, and doesn't damage metal element, and can ensure its original physico-chemical properties and at the same time its technological process is simple.

Description

Method for non-toxic removing glass and ceramic regenerated metal element

The invention belongs to the technology of chemical cleaning and metal element regeneration, and mainly provides a chemical method for separating glass, ceramics and metal elements, which is used for regenerating metal (electronic) elements discarded due to the fusion of the glass and the ceramics.

In the production process of the electronic industry and the medical instrument industry, a large number of unqualified products are involved, and some metal (electronic) elements still meet the use requirements, but cannot be directly recycled due to the fusion of glass or ceramics; these metal components are generally expensive, and some need foreign exchange to import from abroad, which brings great economic loss to enterprises and countries, for example, pins, anode caps and the like in a large number of unqualified glass shells in the production of glass shell factories (kinescope factories) can not be recycled, and large funds need to be bought from abroad; the chemical method currently used by people to dissolve and remove glass is H₂F₂(hydrogen fluoride) or H₂F₂Aqueous solutions (i.e. hydrofluoric acid) or indirect generation of H₂F₂Chemicals such as NH₄F、H₂SiF₆(ammonium fluoride, silicofluoric acid); the problems with these methods are: 1. toxic gas is generated, and the environment is polluted. 2. There is corrosion of metal (except lead and silver) components. 3. The process is difficult to control. In addition, fluorine resources are scarce, costs are high, H₂F₂The product can not be used as a commodity to be put on the market, and the use factories are manufactured at present, so that one-time investment for building factories is often doubled compared with the original plan; these reasons determine that the process route cannot be adopted, and is only used for small-scale glass etching artware and the like.

The invention aims to provide a non-toxic and pollution-free chemical method, which is a method for separating a metal (electronic) element from glass and ceramic which are integrally fused with the metal (electronic) element, namely removing the glass and the ceramic, so that the metal (electronic) element can be regenerated without damage, and the method has the characteristics of reasonability, feasibility and simple process route.

The technical scheme adopted by the invention is as follows: according to the characteristics of metal (electronic) elements required to be recycled and the characteristics of glass and ceramics integrated with the metal (electronic) elements, a solvent is selected to have a penetrating and dissolving effect on a carrier material, namely the glass ceramics, so that the glass and the ceramics are dissolved and removed, and no corrosion effect is generated on the metal elements.

The caustic alkali is used as solvent because all the potassium salt and sodium salt, including potassium-sodium silicate, are soluble in water, the intermolecular attraction force and the bond energy of the molecular structure (common electron pair) of the caustic alkali are small, and when the caustic alkali is heated to a molten state, the conductivity is enough to prove that the potassium salt and the sodium salt are partially or totally ionized into K⁺、Na⁺、OH^-So that the common electron pair is easily converted into

That is, when the nonmetal oxide exists outside, the reaction is easier to be carried out; further, according to the research on the osmotic pressure of Alvarador, the amount of the osmotic pressure (force) of a caustic alkali such as caustic soda or caustic potash which has been melted into a liquid state is inherently related to the concentration thereof, the temperature thereof, and the dissociation and characteristics of the substance itself, and the specific osmotic pressure is determined by the product of the Alvarador constant R and the above relationship. We have found that the small bond energy and the high dissociation degree of caustic alkali are very favorable for the dissolution of non-metal oxides including silicaglass with the help of high temperature, and this is proved by the fact that the caustic soda or caustic potash solution is mixed with SiO at the temperature of 600-700 deg.C₂A boiling reaction can be initiated. Soda ash, sodium sulfide, potassium sulfide, sodium sulfate, potassium sulfate and potassium carbonate can also form molecular structures in the forms of sodium oxide, potassium oxide and the like, and react with the silicon glass ceramic.

The method for removing the glass or the ceramic by using the caustic alkali or the substance which can react with the glass or the ceramic to generate the water glass comprises the steps of heating and raising the temperature to accelerate the reaction speed and the effect of removing, wherein the heating temperature can be the melting temperature of the caustic alkali or the substance which can indirectly generate potassium and sodium oxides to be the lower limit temperature, considering the overheating temperature required by ensuring the chemical kinetics, the working temperature range is more than 400 ℃, and the working temperature is less than the phase transition temperature of a metal element required to be recovered or the temperature of the metal element for changing the geometric shape.

FIG. 1 is a binary phase diagram.

According to binary system (phase diagram), the superheat temperature required by the homogeneous substance to be re-melted is often tens to hundreds of degrees higher than the phase line according to the knowledge of the homogeneous solid-liquid line of the miscible substance, so that the superheat temperature required by chemical kinetics can be ensured, and the equilibrium phase diagram has certain difference from the actual situation, such as different initial states, different heat transfer modes and different time consumption caused by different heated surfaces, we utilize the principle thatThe starting state is different, and the caustic alkali (sodium hydroxide or potassium hydroxide) or the other solvent is melted and heated, and then SiO is added₂When the glass material is dissolved or chemically reacted with the liquid sodium causticized before reaching the homogeneous state, the reaction product is removed at any time even if SiO is formed₂the/NaOH is high and still has the effect of extremely rapid removal of the glass, i.e. always ensuring that the solution is in the working condition of the optimum selection zone.

The technical scheme of the invention considers that before the system interface reaches the equilibrium state, namely, the physical action and the chemical action which are played when the equilibrium is not reached in the initial stage are utilized, under the condition of the same temperature, caustic alkali (such as caustic soda and caustic potash) or other solvent substances are dissolved into liquid, but glass or ceramic is still solid, mutual infiltration and mutual dissolution are started, and when the temperature reaches the reaction temperature, the chemical action appears at the interface (and an infiltration area)Reactions, e.g. caustic soda: ( ) Solid foam-like floaters (because the water glass is still solid at this temperature) appear on the liquid surface along with the appearance of bubbles and the phenomenon of rolling boiling, and the floaters can be removed to improve the utilization rate of caustic alkali.

The container can be a graphite crucible or a metal container such as steel; the required temperature heating can be bottom heating, top heating, induction heating, muffle furnace heating, heat-insulated chamber heating or regenerative chamber heating.

The vessel is charged with caustic or other solvent and heated to melt, and the metal element to which the glass is adhered is added, preferably completely submerged.

When other solvents (except caustic alkali) are used, the solvent may be mixed with glass or ceramic that is fused to the metal element and then put into the container while being heated.

The temperature is continuously increased until boiling (pseudo boiling) is generated, and the temperature is kept for a period of time after the boiling is finished.

Turning over or operating the metal element to eliminate dead angle, wherein the operating temperature is determined according to the property of the metal element to be recovered and preferably not higher than the phase transition temperature of the metal element and the temperature of the metal element for changing the geometric shape.

The invention has the characteristics that:

1. no prior removal of glass or ceramic is required.

2. No toxic gas, no poison discharge and no environmental pollution.

3. It has no corrosion to metal and can maintain the original physical and chemical performance of metal element.

4. The production efficiency is high, and the automation control is convenient.

5. The economic benefit is good, the industrial garbage which can not be treated is changed into useful resources, and a great amount of foreign exchanges in China are saved.

Example (b):

clearing glass of the glass bulb (kinescope) to recycle the pin and the anode cap; NaOH caustic soda is used as solvent, a metal container is prepared, the metal container is heated under a gas nozzle to melt all NaOH, then pins and an anode cap (an element in a picture tube is fused with glass) are put into the metal container to be fully submerged, the temperature is continuously raised until a strong chemical reaction is generated, a false boiling phenomenon occurs, the element is turned over at the end of the reaction, and dead angles are eliminated. The temperature is controlled not to exceed 800 ℃, the metal elements are slightly cherry red (about 780 ℃), and solid matters on the floating liquid surface are removed or not removed. The glass remains unchanged in shape even after a period of high temperature, but due to Na₂O, etc. permeate into the vitreous body, which is deteriorated and can be dissolved after boiling in boiling water for a period of time. Cleaning the cleaned pin, removing the adhered matter with water glass component from the anode cap, alkali boiling, water boiling, sand blasting (controlling surface (smooth finish) surface ratio), oxidizing in special equipment, heating to about 1100 deg.C, permeating hydrogen for some time, and explosion-proof treatment. Cooling to about 800 ℃ and oxidizing. The surface treatment process from sand blasting adopts the prior art, and the complete set of mature treatment technology is provided in the production of the pin and the anode cap of the prior kinescope.

Claims

1. The invention relates to a method for nontoxic cleaning of glass and ceramic regenerated metal elements, which is characterized in that:

a. taking non-toxic caustic alkali which does not damage the metal element as a solvent for removing glass and ceramics fused with the metal element;

b. adopting a substance which can react with glass and ceramic to generate sodium glass and potassium glass as a solvent;

c. the solvent in the container and the glass and ceramic with the metal element are heated, the heating temperature is lower than the melting temperature of the solvent, the working temperature range is above 400 ℃, and the temperature is below the phase transition temperature of the metal element or the temperature of the metal element changing the geometric shape.

2. The method as claimed in claim 1, wherein the solvent is heated in the container to be completely melted, and the glass or ceramic to which the metal element is adhered is put into the container, and the temperature is further raised to accelerate the reaction.

3. The method as claimed in claim 1, wherein the glass or ceramic is mixed with solvent and heated while the glass or ceramic is heated.

4. A method for non-toxic cleaning glass or ceramic regenerated metal element as claimed in claim 1, which features use of sodium carbonate as solvent.

5. A method for non-toxic cleaning of glass and ceramic reclaimed metal parts according to claim 1, wherein sodium sulfide is used as the solvent.

6. A method for non-toxic cleaning of glass and ceramic reclaimed metal parts according to claim 1, wherein potassium sulfide is used as the solvent.

7. A method for non-toxic cleaning of glass and ceramic reclaimed metal parts as in claim 1, wherein sodium sulfate is used as solvent.

8. A method for non-toxic cleaning of glass and ceramic reclaimed metal elements as in claim 1, wherein potassium sulfate is used as the solvent.

9. A method for non-toxic cleaning of glass and ceramic reclaimed metal parts according to claim 1, wherein potassium carbonate is used as the solvent.