RU2660444C1 - Method of processing germanium containing materials - Google Patents

Abstract

FIELD: recycling and disposal of waste.

SUBSTANCE: invention relates to the processing of germanium-containing waste optical fiber. Waste germanium-containing optical fiber is co-fired with germanium-containing coal. Resulting slag co-firing coal and optical fiber wastes is processed into germanium concentrate. Co-firing of coal and germanium-containing optical fiber waste is conducted with the maintenance of the amount of optical fiber waste not more than 10 % by weight.

EFFECT: increase in the yield of germanium in concentrate due to the involvement in the processing of a new promising type of raw materials – waste optical fiber.

1 cl, 4 tbl, 2 ex

Description

The invention relates to the field of metallurgy of dispersed metals, mainly to the field of processing secondary germanium-containing raw materials, in particular waste of germanium-containing optical fiber, to obtain material for processing by one of the known methods with the release of germanium in a germanium concentrate.

Optical fiber (OB) is a quartz, glass or polymer material for transmitting light over a distance. The most common is OM made from high-purity quartz. The method of creating optical fibers with low light losses involves the chemical deposition of special additives from the gas phase. With this method, the deposition of additives can occur on the outer surface of the rotating seed rod, on the end surface of the quartz glass rod, or on the inner surface of the rotating support tube. The most common method of deposition on the inner surface of the tube (IVD). The production process begins with a hollow quartz tube with a length of 0.5-2 m and a diameter of 16-18 mm. In this case, one of the components introduced into the internal cavity of the quartz tube is germanium tetrachloride and water vapor. During further processing as a result of hydrolysis, germanium dioxide is formed, which is deposited on the inner surface. When heating and pulling the tube, the thickness of the workpiece decreases to a standard value of 0.125 mm, with the inner cavity collapsing and the outer surface being covered with a protective layer of polyethylene. As a result, the germanium content is up to 1% by weight of quartz glass or up to 0.04-0.70% by weight of the finished fiber.

In the processes of manufacturing fibers, cables, and especially connecting them to information networks, a number of fatal defects (lateral unevenness of fiber cores, differences in fiber diameters, axial displacement of fibers, and others) are found, leading to their rejection. Due to the high cost of raw materials for optical fiber: quartz (3500-4000 $ / t), germanium tetrachloride (350-400 $ / kg), reuse of waste products from the production of optical fiber and rejected cable (from 30 to 150 thousand rubles / km) seems promising. In addition, the period of operation of fiber-optic lines (20 years) indicates the need to develop a technology for the disposal of used optical cables. It should be noted that in the technical domestic and foreign literature there is no information about the technology for the disposal of organic waste.

In the market of germanium-containing raw materials, batches of organic waste are offered in the form of rolled coils freed from external cable sheaths and packed in cardboard and soft containers, fiber weight from 500 to 650 kg with germanium content from 0.04 to 0.68%, humidity 0.3 up to 1.9% and losses on ignition from 58 to 60%. The average composition of organic waste is characterized by a germanium content of about 900 g / t, a moisture content of 1-2% and losses on ignition from 55 to 60%. The magnitude of the loss during ignition corresponds to the content of polyethylene in the mass of fiber. Moreover, the germanium content per weight of the residue after calcination is in the range from 0.06 to 1.6%. Taking into account that quartz is the main component of optical fibers in a fiber-optic cable, it is advisable to dispose of waste fiber in order to extract germanium using existing technology for processing products with a high content of silicon dioxide. The problem in this case is the release of quartz filaments from the outer polyethylene sheath. Due to the high resistance of polyethylene to the effects of most inorganic and organic solvents, in our opinion, it is advisable to use heat treatment under oxidizing conditions.

A known method of extracting Germany according to Patent RU No. 2058409 C1, IPC ⁷ C22B 41/00, the authors I.N. Tanutrov, O.I. Podkopaev, M.N. Sviridov, publ. 04/20/1994, including electric melting of the agglomerated charge from germanium-containing material, sulfidizing agent and reducing agent. Before melting, the initial mixture is moistened to a moisture content of 25-30%. Melting is carried out while maintaining on the melt surface a charge layer 0.1-0.3 m thick when it is heated at a rate of 5-20 ° C / min. The amount of sulfur in the initial charge is supported by 3-8%.

The use of the analogue is effective in the processing of dispersed germanium-containing materials, such as fly ash from coal burning by a layered method or cyclone smelting sublimates. Application of the method to coarse materials, such as a mixture of fly ash and fly ash from the burning of coal and carbonaceous rocks (mudstones and siltstones), in layered furnaces reveals its shortcomings. The feasibility of joint processing of fly ash and fly ash is determined by the need to increase the overall extraction of germanium from carbon raw materials, since up to 50% of the germanium entering the combustion process goes into coarse dust (fly ash).

The disadvantages of the analogue are:

- the impossibility of obtaining after wetting and agglomeration of the mixture (by pelletizing or briquetting) from coarse materials with a maximum particle size of up to 2-4 mm, such as a mixture of fly ash and fly ash from the burning of coal, agglomerated material with mechanical particle size required for melting with sublimation, mechanical and thermal resistance;

- when melting the agglomerated material prepared in accordance with the closest analogue, the extraction of germanium in sublimates is not more than 60-70% instead of the required 90-92%;

- the multiplicity of enrichment of sublimates with Germany is in the range of 10-15 times instead of the necessary not less than 25-40 times;

- there is a decrease in furnace productivity and an increase in the consumption of electricity and electrodes for melting by 2-2.5 times.

The closest analogue of the invention is a method of processing germanium-containing coals by burning in layered and flame-bed furnaces of hot-water or steam boilers at 1100-1250 ° C (M.Ya. Shpirt. Physicochemical and technological principles for the production of germanium compounds. - Apatity: Publishing House. Kola Scientific Center of the Russian Academy of Sciences, 2009.S. 105-125).

Using the invention allows:

- to extract from 50 to 94% of germanium in the dust products of gas purification leaving the combustion unit, and from 6 to 50% in slag;

- depending on the ash content of the coal and the effectiveness of the gas cleaning system, increase the concentration of germanium in the captured dust from 30 to 130 times in comparison with the source coal.

The disadvantage of the closest analogue is the impossibility of maintaining spontaneous combustion of the polyethylene shell of the waste water without external heat supply and, all the more, the use of heat from the waste products of the waste water waste to heat water or produce steam in a standard boiler with a layer or flare-burning furnace.

The objective of the present invention is to provide a method that allows:

- recycle optical fiber waste by burning in a layered or flare-layer furnace of a hot-water or steam boiler;

- get sublimates and slag used for the production of germanium concentrates;

- increase the volume of processing of raw materials and the production of germanium concentrates.

The technical result of the invention is to increase the production of germanium in concentrate due to the involvement in the processing of a new promising type of raw material.

The specified technical result is achieved by the fact that in the method of processing germanium-containing materials, including burning germanium-containing material in a layered or flare-layer furnace, according to the invention, optical fiber waste is introduced into the charge as a germanium-containing material in an amount of not more than 10 wt.%.

The possibility of carrying out the invention is illustrated by the following examples:

Example 1. An experimental verification of the method was carried out using waste OM and germanium-containing coal from the Pavlovsk deposit (table 1). For the joint burning of coal and waste, samples of OM waste were cut into 200-500 mm long filaments, coiled from them, loaded into an alundum boat and covered with a layer of coal crushed to minus 1 mm. The amount of OM in the mixture was 5%. The mixture was subjected to oxidative roasting under conditions of layer-by-layer burning in a furnace ТЛЗ-2-2,7 / 4,0 of a boiler ДКВР-10, temperature 1250 ° С, duration 60 min, heating rate 20 deg / min, air excess coefficient 1.5. The output of slag after combustion was 54.7% by weight of the dry mixture, the germanium content in the slag was 0.14%. The extraction of germanium from the mixture into slag was 59%. The rest of Germany went into sublimates for separate processing to concentrate.

From a slag of co-layer burning of coal and OM, a mixture was prepared for reduction-sulphiding smelting with additives (table 2) of hydrated lime (calcium oxide hydrate) and alabaster (calcium sulfate hemihydrate) by mixing slag (62-75%) with lime additives (5-22 %) and alabaster (8-25%). The mixture was mixed and crushed to a particle size minus 0.4, moistened to 14-15% and briquetted at a pressing pressure of 500 kg / cm ² . As a result of the preparation of the mixture, briquettes with a moisture content of 14.4%, compressive strength of 115 N / cm ² , basicity of 0.6-0.7, and sulfur contents of 4-5%, meeting the requirements for a charge of reduction-sulphiding melting, were obtained. The finished briquettes were melted at a heating rate of 20 deg / min to a temperature of 1550 ° C, followed by exposure of the melts at this temperature for 30 minutes, with the sublimation of germanium in the form of monosulfide and oxidation of the vapor-gas phase by suction of air. As a result of smelting, sublimates with a content of 6.5% germanium were obtained, suitable for producing germanium concentrate. The germanium recovery to sublimates was 95.4%.

Example 2. Samples with OM contents in the mixture of up to 12 wt.% Were prepared from the wastes of OM and germanium-containing coal of the Pavlovsk deposit. For experimental verification of co-combustion of coal and waste, samples were used (table 1). Samples of OM waste were cut into 200-500 mm long filaments, coiled from them, loaded into an alundum boat and covered with a layer of crushed coal (table 2). The sample was loaded into a muffle furnace equipped with a device providing a programmable heat treatment mode with temperature control and regulation of the heating mode. The control of the heat treatment was supplemented by an analysis of the compositions and yields of products before and after combustion.

The combustion results are shown in table 3. They confirm the possibility of co-burning of coal and OM waste. The content of germanium and silicon dioxide in the firing slag in the range of waste additives up to 10 wt. % increases in proportion to the amount of germanium and silicon in the waste OM. In other words, all germanium, as well as silicon, introduced into the mixture with OM waste, is completely transferred to slag burning. The increase in waste additives in excess of 10 wt.% Leads to a decrease in the extraction of germanium in sublimates, and also does not provide the full oxidation of the polyethylene sheath of quartz filaments. The latter is observed during grinding and averaging of co-incineration residues. The content of the components of the averaged residue of co-combustion of coal and OM wastes was,%: Ge - 0.14; Fe _total - 1.96; CaO - 2.10; MgO - 1.08; Al ₂ O ₃ - 11.45; SiO ₂ 47.73; C - 8.10; S 0.20; Na ₂ O - 0.40; K ₂ O - 1.30. Comparing these data with the composition of ordinary slag (table 1), we can note their proximity. At the same time, a part of germanium, introduced into slag with OM waste, is present in the form of a solution in quartz glass, which can negatively affect the results of reduction-sulphiding smelting. Since the target product is released from the dust and gas phase, to increase the germanium content in it, it is necessary to agglomerate (briquette) the mixture.

The optimal composition of the charge of sulphide reduction smelting meets the following requirements: the basicity of the charge (ratio (CaO + MgO) / SiO ₂ ) equal to 0.6-0.7, the content of sulfate sulfur in the briquettes is about 5.5%, which ensures the extraction of germanium in sublimates about 95%. To obtain a mixture of the optimal composition used calcium hydroxide (slaked lime) and calcium sulfate hemihydrate in the form of alabaster (table 2).

The crushed samples of the mixture (table 3) with variable content of sulfate sulfur, introduced in the form of alabaster, and basicity were subjected to wetting and then briquetting at a pressing pressure of 500 kg / cm ² .

The resulting briquettes were characterized by the following properties:

- humidity - 14.4%;

- bulk density of raw briquettes - 0.9 t / m ³ ;

- raw density - 1.4 t / m ^3, dry - 1.2 t / m ^3;

- wet compressive strength - 115 N / m ^2, dry - 200 N / m ^2.

The finished briquettes were subjected to sulphiding reduction smelting. As a result, it was found that during the joint burning of organic waste with germanium-containing coal in the range of additives up to 10%, a complete oxidation of the polyethylene sheath of the optical fiber is observed simultaneously with the organic component of coal. In this case, the quartz component passes into the slag residue, increasing its yield and the amount of germanium in it. An increase in additives of more than 10% leads to incomplete oxidation of the polyethylene shell of a quartz thread.

Analysis of the data on the composition of the molten melting products (table 4), as well as the loss of germanium with slag and a sulfide-metal alloy on the sulfur content and basicity of briquettes leads to the following conclusions:

- briquettes using slag for co-burning coal and OM waste with a sulfate sulfur content (about 5%) and basicity in the range of 0.5-0.7 during smelting ensure germanium extraction into sublimates of at least 95%;

- indicators of briquette smelting using slag of co-burning coal and OM waste are within the limits of processing of ordinary slag of layer-by-layer burning of germanium-containing coal. At the same time, the average germanium content in the sublimates obtained by modeling the briquettes smelting was 6.5-10%, which is close to the germanium content in the sublimates of the briquettes smelting from ordinary products of the combustion of germanium coals.

Claims (1)

A method of processing germanium-containing materials, including burning a mixture of germanium-containing material in a layered or flare-layer furnace with the extraction of germanium into a solid residue in the form of slag and sublimates, characterized in that the mixture consists of germanium-containing coal and waste germanium-containing optical fiber taken in the amount of not containing fiber more than 10 wt.%.