USE OF LOW-SPARKING MATERIAL WHEN HANDLING BULK GOODS

Abstract

The invention relates to an apparatus for handling bulk material which contains fines which can lead to formation of explosive dust/air mixtures, where the apparatus comprises moveable internals in a housing which comes into contact with bulk material, characterized in that the moveable internals and/or the interior of the housing which comes into contact with bulk material consist of aluminum bronzes or are lined and/or coated with the aluminum bronzes.

Claims

1. An apparatus for handling bulk material, comprising movable internals in the interior of a housing which comes into contact with bulk material, wherein the movable internals and/or the interior of the housing which comes into contact with bulk material consist of an aluminum bronze or various aluminum bronzes or are lined and/or coated with an aluminum bronze or various 5 aluminum bronzes.

2. The apparatus as claimed in claim 1, wherein the interior of the housing which comes into contact with product or the movable internals are lined and/or coated with the aluminum bronzes.

3. The apparatus as claimed in claim 1, wherein the aluminum bronze is nickel-free.

4. The apparatus as claimed in claim 3, wherein the aluminum bronze is AMPCO 25.

5. A product comprising aluminum bronze as a material for at least one movable internal and/or the housing of an apparatus for handling bulk material.

Description

[0041] It was therefore an object of the invention to provide a solution in order to reliably prevent an explosion in the interior of one of the abovementioned units, which allows utilization of the plant at relative velocities between parts moved relative to one another of up to 20 m/s. As a result of this ignition source avoidance, it would be possible, unless required by other circumstances, to dispense with making the abovementioned unit or upstream and downstream parts of the plant inert.

[0042] It is known from the literature that, subject to particular prerequisites, mechanical sparks which can cause ignition do not occur in the case of some materials and pairings of materialssee, for example, Henrikus Steen Handbuch des Explosionsschutzes, Verlag Wiley-VCH, Weinheim 2000, ISBN 3-527-29848-7; Heinz Helmuth Freytag Handbuch der Raumexplosionen, Verlag Chemie GmbH, Weinheim 1965; BGI 533 (DGUV Information 209-001Safety when working with hand tools, version: May 2007). This is also indicated in the regulatory publications (see, for example, DIN EN ISO 80079-36: December 2016chapter 6.4.3; DIN EN ISO 80079-36: December 2016chapter 6.4.2.1), according to which mechanical sparks do not have to be taken into account as effective ignition source in these cases. These materials include copper (Cu), zinc (Zn), tin (Sn), lead (Pb), some brass alloys (CuZn) and bronze alloys (CuSn).

[0043] It is likewise known that materials which count as low-sparking, including not only the abovementioned materials but also beryllium bronzes (CuBe) (BGI 533DGUV Information 209-001Safety when working with hand tools, version: May 2007) can be used for producing hand-held tools for use in explosion hazard regions of zone 0 and with materials of the explosion group IIC (e.g. chisels, hammers, spanners).

[0044] Such materials have hitherto only been used as materials for hand-operated tools.

[0045] To achieve the abovementioned objects, aluminum bronzes (CuAl alloys) are used according to the invention as material for the movable internals in the abovementioned units and/or for housings of abovementioned units in order to avoid mechanically generated sparks.

[0046] The object has been achieved by an apparatus as claimed in claims 1 to 4.

[0047] The interior of the housing which is in contact with product or the movable internals are preferably lined and/or coated with the abovementioned materials. Preference is given to nickel-free aluminum bronzes as material for the abovementioned applications. These have not been previously known for this application. For example, the suitability of a specific nickel-free aluminum bronze, AMPCO 25 from AMPCO Metal S.A. has been examined and proven at the German Federal Physical-Engineering Laboratory (Meyer, L., See conclusion of the research project to examine the ignition effectiveness of mechanical sparks when using bronze, ptb 2015-11). These studies in respect of the ignition effectiveness on mechanically generated sparks on an aluminum bronze indicated that no visible mechanically generated sparks occurred in the relevant range of relative velocity and contact pressure. Even ethene/air mixtures, which are significantly more ignition-sensitive than dust/air mixtures in respect of mechanically generated sparks, could not be ignited. However, due to the temperatures occurring at the friction pin, hydrogen/air mixtures, which are even more ignition-sensitive than ethene/air mixtures, could be ignited.

[0048] L. Meyer writes: The experiments showed that when the bronze alloy was rubbed against the chromium steel at velocities in the range from 1 m/s to 20 m/s and contact pressures in the range from 1 N/mm.sup.2 to 40 N/mm.sup.2, no mechanically generated sparks were able to be observed. [ . . . ] In ignition experiments using ethene, no ignitions could be brought about when using friction partners from among the present materials.

[0049] It can be deduced from this result that not only the materials mentioned in (DIN EN ISO 80079-36: December 2016chapter 6.4.3; /5/DIN EN ISO 80079-36: December 2016chapter 6.4.2.1) copper (Cu), zinc (Zn), tin (Sn), lead (Pb), some brass alloys (CuZn) and bronze alloys (CuSn)) but also aluminum bronzes are suitable as material or material for lining or coating of units and/or for the moving internals thereof in respect of avoidance of effective ignition sources (here mechanically generated sparks and small hot surfaces) up to relative velocities of 20 m/s and contact pressures of 40 N/mm.sup.2, and this combined with good wear properties. The patent application further provides for the use of aluminum bronze as material for at least one movable internal and/or the housing of an apparatus for handling bulk material.

[0050] The field of application for the use of aluminum bronze as material for lining or producing housings or for movable elements of the abovementioned units encompasses the following sectors of industry: [0051] Pharmaceutical industry [0052] Agrochemical industry (including treatment of seed for sowing) [0053] Food industry [0054] Chemical industry [0055] Power stations [0056] Plastics industry [0057] Wood-processing industry

[0058] The proposed use of aluminum bronze encompasses the manufacture of the moving and/or static parts of the units for handling bulk materials, both as solid material and as covering (e.g. coating, cladding, adhesively bonded material) on a main element not made of aluminum bronze, by one of the methods customary in the prior art, e.g. cutting-machining shaping according to mechanical requirements.