WO1992020070A1

WO1992020070A1 - Oleaginous earth processing method

Info

Publication number: WO1992020070A1
Application number: PCT/FR1992/000388
Authority: WO
Inventors: Michelle Jacquin; Bernard Rimala
Original assignee: Electricite De France
Priority date: 1991-05-02
Filing date: 1992-04-30
Publication date: 1992-11-12
Also published as: FR2676141A1

Abstract

A method for definitively solidifying and storing contaminated earth which has been used to purify lubrication oils from machines in nuclear power stations, e.g. primary circuit pumps. The method comprises cementing the contaminated earth and plasticizing the oils contained therein with a preferably polybicycloheptene-based plasticizer. The method is useful for the storage of contaminated oleaginous earth.

Description

PROCESS FOR CONDITIONING OILY SOILS

DESCRIPTION OF THE FIELD AND ORIGIN OF THE INVENTION The invention relates to the treatment of filtration earths loaded with oil, so that they are put into solid form and without oil the residual free. The main application of the invention is for land which has served as a filter during the decontamination of the lubrication oils used in nuclear installations.

Recycling or disposing of contaminated oil in the nuclear industry requires that it be decontaminated first. Their decontamination is obtained by filtration on soils such as fuller's earth or diatomaceous earth which retains the radioactive particles which are the source of contamination of oils.

After the contamination operations of the oils, we obtain on the one hand oils whose residual radioactivity is low enough to allow their re-use or their evacuation and on the other hand a mass of oily earth loaded with rad oactive particles. As a result, these soils constitute radioactive waste which should be stored on a site reserved for this type of waste and managed by ANDRA (National Agency for Waste Management RAdi oa cti fs ⁾ . To be admitted to such a site, radioactive waste must comply with certain safety rules. They must in particular be put in a form such that they have the following characteristics:

- not be dispersible;

- not be flammable; and

- do not deform or exude liquids under a pressure of 0.35 MPa (3.5 bar); and in the case of oily soils, do not contain Free oil.

The object of the invention is to allow the final storage of oily earths by putting them in such a form. It applies to land from

Oil decontamination, but it can also apply to any soil contaminated with oils or hydrocarbons for any reason. This requirement appears to be new on the filing date.

SUMMARY OF THE INVENTION

The main object of the invention is a process for conditioning oily soil. According to the invention, it consists of cementing

The earths and simultaneously plasticize the oils contained in these earths by means of a plasticizing agent.

The main embodiment of the invention provides that the plasticizing agent is a binder based on polybi cycLoheptene. Preferably. The product used comprises 97.5% of polyhexylic Loheptene, 1% of anti-caking agent, 1% of anti-oxidant and 0.5% of residual volatile matter. In the main embodiment of the invention, the cementing is carried out with cement, water and earth to be cemented. The implementation of this cementing is done for example with the following ranges of weight percentages: - 37 to 55% of cement;

- 25 to 40% of land;

- 17 to 20% water; and

- plasticizing agent in the proportion of 20% of the weight of the soil. Cementing is particularly effective when using by weight:

- 36% cement;

- 36% of land;

- 20% water; and - 8% plasticizing agent.

The implementation of the process is particularly effective when the four ingredients are mixed for half an hour.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

The method according to the invention will be better understood on reading the following description. The example of embodiment described relates to land which has been used for the filtration of oils contaminated during their use in nuclear power plants. These earths are generally hydrosi Li cates of aluminum and are activated with the acid. This type of soil has a specific weight of 2.4 kg / L, but its apparent density, when it is not packed, is around 450 g / l and its apparent density, when it is packed, is about 670 g / l. Chemical composition :

Siθ2, AI2O3, Fe2Û3, MgO, CaO, Na2θ, K O Physical and chemical properties:

- Humidity (2 h, 110 ° C) 7% maximum

- Loss on ignition (1000 ° C) 7% maximum - pH (10% suspension) 2.5-3

Particle size analysis ^* (sieving):

- 150 m (DIN 40) 97%

- 75 m (DIN 80) 88%

- 60 m (DIN 100) 80% Before applying the process according to

The invention, it is advisable to extract from this earth the maximum possible oil. This extraction will preferably be carried out by centrifugation, the extraction of the oil by compression giving less good results. It is estimated that after centr fugati on, there is still 30 to 40% oil by weight in the land.

According to the invention, the method consists in completely cementing the earth to be stored. The solidification of the oil contained in the soil must also take place at the same time as the cementing. It is obtained by means of a plasticizing agent. The agent used is preferably a commercial product dried by the firm N0RS0L0R, under the name of N0RS0REX AP. This product is a Binder based on polybi cycloheptene. It has the following characteristics. Intrinsic characteristics

- Chemical nature pol bi cyc loheptene

- Formula (C ₇ H ₁₀ ) _n

- Molecular mass 2,000,000

- White powder appearance

100% <2 mm

85% <0.8 mm

- Bulk density 0.40 _, + _ 0.02

- Actual density 0.96 Composition:

- Polybi cyc Loheptene 97.5%

- Anticaking (stearic acid) 1% - Antioxidant 1%

- Volatile residual materials 0.5% This material is more effective than simple absorbents or adsorbents commonly used, such as clay, bentonites, green ve rmi eu, fly ash, cements, vegetable fibers or polyprolene. The cement used is a fast cement such as that sold by establishments.

LAFARGE under the name "CPA 55".

The process can be carried out in any container in which it is possible to mix and mix the ingredients. A metal drum or a simple concrete mixer can be used for this purpose.

The proportions given in the following paragraphs are only indications of one or more possible implementations and are given as an indication. To cement and block 100 kg of oily, contaminated soil or diatomaceous earth, a weight equal to approximately 100 kg of cement is used. The plasticizing agent, preferably N0RS0REX, is then used at a rate of 22 kg in this case. 55 liters of water are then necessary to make the mixture.

To verify the effectiveness of such an implementation, tests were carried out. Indeed, a visual examination, after cutting along a vertical plane, showed a very homogeneous appearance of the whole. On the other hand, an exudation test, in immersion, under a pressure of 0.35 MPa showed the absence of iridescence, which indicates the absence of supernatant oil after a week. A test carried out according to the VICAT needle showed complete solidification after seven hours of rest.

In general, the percentages by weight of the optimal composition are as follows:

- 36% cement; - 36% of land;

- 8% plasticizing agent (N0RS0REX); and

- 20% water.

However, the method can be implemented with similar proportions, in particular when these are included in the following ranges of percentages by weight:

- 37 to 55% of cement;

- 25 to 40% of land;

- 17 to 20% water; and - plasticizing agent in the proportion of 20% of the weight of the soil. ADVANTAGES OF THE PROCESS ACCORDING TO THE INVENTION Many advantages are inherent in the process according to the invention.

1 ⁾ Handling of N0RS0REX AP as a plasticizing agent:

- Presentation in powder, therefore easy dusting, spreading, spraying or incorporation on or in The pollutant or the waste to be treated.

- Absence of toxicity. - Absence of abrasive character.

- Chemical inertia.

2) Treatment of pollutant or waste:

- Significant and rapid absorption, followed by a total and irreversible plasticization of most hydrocarbons and chemicals, with the exception of alcohols, diols, ethers and acids.

- Hydroca rbure / NORSOREX AP ratios from 5 to 20, depending on the type, in particular for domestic fuel (10) or PCBs (15). - Completely hydrophobic character, therefore absence of water absorption.

- Density of 0.96, therefore absence of entrainment towards the bottom of aqueous layers.

- Inertia vis-à-vis the mineralization of water. - Conversion of pollutants and waste into masses of high consistency, even at high dilution, thanks to the very high molecular mass of N0RS0REX AP.

- High efficiency even when cold (-10 ° C).

3) Recovery, packaging, transport: - Obtaining very consistent layers or masses, easy to recover with a shovel or a net.

- Very limited swelling rate (10% ⁾ During the solidification process, so volumes to recover and to condition much lower than those obtained with treatments with mineral absorbents, fly ash, cements, etc. (50-200% swelling). This characteristic is particularly appreciable during the treatment of hazardous, toxic or nuclear waste which must, after solidification, be packaged in specific and expensive containers. It also limits the volumes to be transported during transport to evacuation or disposal zones or installations.

4) Incineration:

- Limitation of volumes to be incinerated.

- Purely hydrocarbon nature of N0RS0REX AP, therefore negligible ash rate. - No corrosion generator.

- High calorific value.

- Does not lead to toxic derivatives or residues.

5) Burial:

- Irreversible and final fixation of the pollutant or waste.

- No subsequent exudation, even under the effect of ground pressure.

- No extraction of the pollutant or waste under the effect of seepage or runoff water, therefore safety from the water table.

- N0RS0REX AP is non-biodegradable and therefore ensures safe solidification of pollutants or waste even in the long term, in the event of burial or storage at authorized landfills or depots. To summarize, this process allows to put

Oily soils in the desired form by simple processing means and using readily available products. Proportions indicated allow to condition a satisfactory amount of soil relative to the weight of ingredients used while having a large margin in terms of compressive strength. The plasticizer used is in the form of a non-toxic white powder. It is not abrasive and chemically inert. It is therefore easy to use and this without special precautions. Hydrophobic in nature, this product does not act on water but only on the oil contained in it.

The process according to the invention therefore allows to solidify a large mass of contaminated soil and thereby purify a large amount of the lubricating hui conta i born ^'During their stay in the primary pumps central nucléai res. The residual contamination of these oils can drop below 10 ^" ^ Ci / m ³ and allows them to be recycled in the public domain. Blocking by cementing and soli di fi cati on, so contaminated land allows to respect the standards defined by ANDRA.

The application to the nuclear industry of the process according to the invention is an example of implementation. In general, this process can be applied to materials other than earth thus contaminated by radioactivity. The origin of the residual oils, in this case organic or synthetic oils, and the nature of the cementing or plasticizing agents used can obviously change. The formulation of implementation will then have to be adapted to the product used.

Claims

1. A process for conditioning oily soil, characterized in that it consists in cementing the soil and simultaneously plasticizing the oil contained in the soil by means of a plasticizing agent.

2. Method according to claim 1, characterized in that the plasticizing agent is based on polybi cycLoheptene.

3. Method according to claim 1 or

2, characterized in that the cementing is carried out with cement, water and earth to solidify.

4. Method according to claim 3, characterized in that the cementing and solidification are carried out with the following proportions by weight:

- 37 to 55% of cement;

- 25 to 40% of land;

- 17 to 20% water; and - plasticizing agent in the proportion of 20% of the weight of the earth.

5. Method according to claim 3, characterized in that the cementing and plasticization are carried out with the following percentages by weight:

- 36% cement;

- 36% of land;

- 8% plasticizing agent; and

- 20% water.

6. A method according to resold cati on 2, characterized in that the plasticizing agent has the following composition by weight: - 97.5% of poLybi cc Loheptene;

- 1% anti otant;

- 1% antioxidant; and

- 0.5% residual volatile matter.

7. Method according to any one of the preceding claims, characterized in that the ingredients are mixed for a period equal to half an hour.