WO1993001898A1

WO1993001898A1 - Process for continuous treatment of dirty small pieces

Info

Publication number: WO1993001898A1
Application number: PCT/CS1992/000004
Authority: WO
Inventors: Milos^¿ SEKYRA; Lubos^¿ CHOURA; Karel DLOUHY^´; Markéta BERNÁTOVÁ; Jan PÍS^¿E; Jaroslav JELÍNEK
Original assignee: Ekospan Sro
Priority date: 1991-07-16
Filing date: 1992-02-17
Publication date: 1993-02-04
Also published as: CS220391A3; CZ278398B6

Abstract

A process relates to continuous treatment of dirty fine pieces, particularly scrap metal cuttings, by ultrasonic action, wherein oil, oily emulsions and impurities are collected and liquidated in said process. Contaminated material is withdrawn continuously from a depositing place and is sorted, wherein sorted material fraction is dispersed into a degreasing water bath with a temperature 50° to 80 °C and falls by action of gravitational forces. Material is repeatedly dispersed during said sinking movement and is subjected to ultrasonic action. Sinking velocity of the material particles is so reduced. Material is raised after passing said water degreasing bath, is centrifuged and spread by vibrating action into a layer and dried, thereafter is briquetted after previous magnetic separation. Oily mixtures produced during said treatment are subjected to mechanical and gravitational water and oil separation. Chemically stabilized oily emulsions are destroyed by electric current, oil is mechanically and gravitationally separated and a water fraction is returned back into the process.

Description

Process for continuous treatment of dirty small pieces

Background of the Invention

An invention relates to a process for continuous treat¬ ment of dirty fine pieces, particularly metal scrap produced in cutting processes, by ultrasonic action, wherein oily emulsions are collected and liquidated in said process.

Prior Art

Metal scrap produced in a cutting process and comprising cuttings is contaminated with lubricating and cooling oily emulsions containing greasy substances in an extent from 5 to^' 15 wt. percent. Manipulation with said materials and a waste recovery jeopardize an enviroment. For example, oily emulsi¬ ons leaking from the transport means during the waste materi¬ al transport to the processing plant may contamine soil and pollute surface and soil waters. Cuttings and other metal scrap are melted in some plants, but said process produces a great amount of harmful substances which pollute atmosphe¬ re. Generally utilized cleaning devices and plants for waste gases being produced in the cuttings waste melting process are reliable effective, when a content of grease substances decreases under 2 wt. percent. Moreover, melting process pro¬ viding grease substance and cuttings melting requires an in¬ creased power consumption. Hereto known devices and plants for grease substance removing by centrifuging are not suffic¬ ient in effectivity, wherein refuse incineration furnaces are expensive. Hereto known degreasing processes and devices are based upon physical and chemical properties of fat films and coats, on solubility in organic solvents and emulsibility thereof. A fat substance saponification in alcalies lacks suitability for waste material treatment, as the cuttings waste material contains grinding sludge with dust and a mix¬ ture of mechanical impurities and degreasing agents. Devices and processes for electrolytic degreasing by electric current action lacks any advantage for the same reasons. Ultrasonic degreasing of metal parts in a device comprising an ultraso¬ nic tank with a membrane being disposed on a bottom of the tank and containing active dissolvents for degreased elements inserted into the tank in stable positions lacks any advanta¬ ge, too, as the deposited grinding sludge, dust and fine im¬ purities absorb ultrasonic waves coming from the ultrasonic emitters and degreasing efficiency is reduced.

Therefore it is an object of the invention to provide a process for continuous treatment of dirty small pieces which would be able to liquidate fat substances in scrap me¬ tal efficiently.

Summary of the Invention

To attain the above mentioned object, according to this invention there is provided a process for continuous treat¬ ment of dirty fine pieces comprising steps of continuously withdrawing the waste material from the deposit place and sorting thereof, dispersing a scrap material fraction with particle size 2 to 50 mm into a degreasing water bath having a temperature 50° to 80°C, dipping said scrap material par¬ ticles by gravitational action into greater depths of the water bath, wherein the sinking particles rebound repeatly during said dipping movement on rigid barriers for additional dispersion of the particles in the water bath simultaneously with ultrasonic action and counter-flow action onto sinking particles in the water bath for decelerating the particle movement speed, raising the treated material and rinsing thereof, thereafter centrifuging continuously, levelling evenly by vibration and drying said treated material.

Material fractions with greater particle size than 50 mm are advantageously crushed or teared and are returned into the sorting process. Heavy contaminated material fractions with particle size from 2 to 50 mm are preliminary centrifug- ed before entering the degreasing bath.

Description of the Preferred Embodiment

The invention will now be described further, by way of non-limiting examples.

Metal cuttings produced in cutting processes and compris¬ ing particularly from 5 to 15 wt. percent of cutting oils are collected on a a deposit place where gravitational separation takes place and separated oil impurities run-down into a sump. Cuttings are then transported from the deposit place into a receiving hopper and discharged continuously into a vibrating sorter, where some hours supply for a degreasing device is provided. The hopper is supplied regularly and is provided with a discharge device for a required amount of ma¬ terial regulation. Cuttings fall from the receiving hopper onto a vibrating sorter being formed by a linearly oscillat¬ ing sorting machine with 12 to 0,5 mesh sieve. Particles of greater size and clotty particles which are not suitable for next treatment are separated on the vibrating sorter. Cut¬ tings are then transported by a chain scraper conveyer into an ultrasonic degreasing device. The *^• chain scraper conveyer is provided with a collecting tank for oily impurities in a lower part thereof.

The ultrasonic degreasing device consists of a vertic¬ al hollow body being broken across in some cascade steps and comprising a closed raising conveyer in the lower part there¬ of forming with said body communicating vessels being filled with water bath having temperature of 60°C. The hollow and across broken body is divided by transverse faults inclined in an angle of 45° to horizontal plane into four broken sect¬ ions being disposed one above the other. The ultrasonic emit¬ ters acting with frequency of 20 kHz are mounted in walls op- posing to oblique lower walls.

Contaminated and sorted cuttings are scattered in the water bath and fall by action of own weight into a greater depth of the water bath and are spread again in the water bath after overfall over edges of the across broken body. The degreasing device is provided with nozzles in each of the broken sections which force water in direction opposite to the cuttings movement direction; fall speed of particles is so decelerated and cuttings are exposed to ultrasonic effect for a longer time.

Cuttings are then elevated by a conveyer from the degrea¬ sing device and are transferred in a continuous centrifuge for centrifuging and subsequent transporting with oil content decreased substantially onto 1 to 1,5 wt percent and with residue moisture about 1 wt percent. Cuttings fall through a chute into an inlet of vibratory drying screw conveyer and are dried during said movement by warm air.

Dried chips are briquetted in the end and said operation decreases a content of fat substances on a half of previous content, i.e. under 1 wt. percent. When said method treats the brass chips, briquets having diameter about 100 mm and weight 3 kg and comprising effectively no residue humidity.

Oil, oily emulsions and impurities are discharged during the whole treatment of the scrap chips from the seating place, from the centrifuge and the sorting operation and from a surface of the degreasing bath and are, according to a nature of impurities, subjected to mechanical and gravitat¬ ional water and oil separation. Separated oil is chemical un¬ stable and is discharged into a reservoir, wherein water with emulsion and residue oil is discharged from the degreasing bath and from the centrifuge into a regenerating circuit. Water fraction with chemical stabilized oily emulsions are subjected after hydrogen exponent pH regulation to electric direct current action. Water is at the same time stirred up and the chemical stabilized emulsion is broken after a cert¬ ain time.

The treated water with precipitated oils is then direct¬ ed through a gravitational sorption separator, where it ad¬ heres on the one hand on a fibrous sorbent consisting of fib- roil staple fibres and is separated on the other hand from water. Oils are directed again into the reservoir, wherein water streams into an equilization basin. Water is treated in the equilization basin by microfiltering process, i.e. micro- molecules of water are forced through ceramic barriers and macromolecules of oils and fats are trapped on the ceramic barriers. Water circulates in closed cyclus and being return¬ ed in the greasing bath again.

Method for continuous treatment of dirty small pieces according said invention is applicable for scrap metal cut¬ tings and other fine metallic or non-metallic piece treat¬ ment.

Claims

CLAIMS :

1. A process for continuous treatment of dirty fine pieces, particularly scrap metal cuttings, by ultrasonic action and with oil and oily emulsion collection and liquidation, wherein contaminated material is collected on a depositing place and oily impurities are separated there by gravitational separation and run-down into a sump, c h a r a¬ c t e r i z e d i n t h a t comprising steps of continuous¬ ly withdrawing the waste material from the deposit place and sorting thereof, dispersing a scrap material fraction with particle size 2 to 50 mm into a degreasing water bath having a temperature 50° to 80°C, dipping said scrap material par¬ ticles by gravitational action into greater depths of the water bath, wherein the sinking particles rebound repeatly during said dipping movement on rigid barriers for additional dispersion of the particles in the water bath simultaneously with ultrasonic action and counter-flow action onto sinking particles in the water bath for decelerating the particle movement speed, raising the treated material and rinsing thereof, thereafter centrifuging continuously, levelling evenly by vibration and drying said treated material.

2. A process as claimed in claim 1, c h a c t e r i z e d i n t h a t the material fraction with greater particle size than 50 mm is crushed or teared and is returned into a sorting process.

3. A process as claimed in claim 1 or 2, c h a r a c t ¬ e r i z e d i n t h a t the heavy contaminated material fraction with particle size from 2 to 50 mm is preliminary centrifuged before entering the degreasing bath.

4. A process as claimed in at least one of claims 1 to 3, c h a r a c t e r i z e d i n t h a t when the treated material consists of a mixture of metals, iron metals are separated magnetically after drying said mixture of metals.

5. A process as claimed in at least one of claims 1 to 4, c h a r a c t e r i z e d i n t h a t the dried material is briqueted for residual moisture and fat substance content decreasing and resulting volume contraction.

6. A process as claimed in at least one of claims 1 to 5, c h a r a c t e r i z e d i n t h a t oil, oily emulsions and impurities are discharged from the sump, from the centrifuging and sorting process and from the degreasing bath level during the degreasing process, wherein in accordance with nature of contamination, produced oily mixtures are subjected to mechanical and gravitational water and oil separation, water fraction with chemically stabilized oily emulsions being subjected to electric direct current action after hydrogen exponent pH reduction and oil is then separated by mechanical a gravitational sorption action and the winned water fraction is returned after microfiltration into the degreasing process, wherein oil winned in all previous operations is collected.