FR2763936A1 - Aqueous binder for scrap battery consolidation and stabilisation - Google Patents

Abstract

A novel aqueous binder consists of a mixture of slag cement powder, a magnesium ion source, a phosphate ion source and water, the magnesium content being 2.5-75% (by wt. of binder) and the phosphate/magnesium wt. ratio being 1-4. Preferably, the magnesium ion source is magnesium oxide or hydroxide, dolomite or a magnesium salt and the phosphate ion source is phosphoric acid or sodium, potassium, calcium or magnesium phosphate. Also claimed is a process for consolidation and stabilisation of scrap batteries by grinding the batteries, optionally magnetically removing iron and incorporating the ground material into the above binder, preferably in a binder/ground material wt. ratio of 0.175-1.5. Further claimed are consolidated and stabilised scrap batteries obtained by the above process.

Description

The invention relates to the field of the environment. More precisely,
The invention relates to the reprocessing of used batteries.

 Due to its composition, the used battery must be considered as a highly polluting waste for the environment.

 Indeed, it contains metal elements recognized as toxic such as zinc, cadmium, lead, mercury, silver, manganese, copper, lithium and even traces of indium. These elements may be present in metallic form and / or in the form of oxides.

 There are also electrolytes that consist of concentrated solutions of acid (sulfuric acid), strong bases (sodium hydroxide or potassium hydroxide) or salts (zinc chloride or ammonium chloride). In some cells even organic solvents such as dimethylsulfoxide or propylene carbonate are used.

 Finally all these toxic elements are enclosed in a metal or plastic envelope.

 It is therefore obvious that this waste with significant pollutant potential must no longer be thrown into the natural environment.

 Until now, the main developments in this field have been made with a view to recycling the various metals contained in the batteries. However, this technique requires numerous operations in order to separate the various constituents of the cells firstly by physical methods and then by means of hydrometallurgical processes for recovering and separating the various heavy metals in the metallic state with a view to their valuation.

 There is therefore an undeniable need for a simple and effective way of fixing the heavy metals batteries thus allowing a storage of treated products elimination center authorized by the regulations. The use of a system based on hydraulic binders to solidify and stabilize such waste may be a treatment solution.

 However, the presence of high levels of heavy metals, especially zinc and lead, makes it difficult to develop a composition for good retention of toxic species.

 The object of the invention is therefore to provide a composition which makes it possible to obtain a material having good mechanical properties because of its ability to solidify, even in the presence of large amounts of zinc and lead, as well as a very high good ability to chemically fix heavy metals.

 Thus, a first aspect of the invention relates to an aqueous binder for the solidification and stabilization of used batteries, consisting of a mixture comprising a slag cement powder, a source of magnesium ions, a source of phosphate ions and water.

According to the invention, slag cement is understood to mean, for example blast furnace cement, in particular of the CLK-CEM-III / C, CHF-CEM III1A or III / B type or of the slag and ash cement, especially of type CLC-CEM V / A or
V / B, as defined according to standard NF P 15-301.

 In accordance with the invention, the cement powder advantageously has a particle size of less than 200 μm, preferably less than 100 μm.

 According to the invention, the magnesium ions may be provided in particular by magnesium oxide or hydroxide, for example calcined dolomite, magnesium lime, or a magnesium salt such as, for example, chloride, sulfate or nitrate. , magnesium carbonate or phosphate.

 The phosphate ions can in turn be provided in particular in the form of phosphoric acid, sodium or potassium phosphate (mono, di or trisodium, or mono, di or tripotassic), calcium phosphate, in particular in the form of CaHPO4,2H2O, or magnesium phosphate.

 The aqueous binder according to the invention has a pH of from about 8 to about 13, preferably from about 9.5 to about 12.5. To obtain such a pH, it is necessary that the magnesium proportion is between about 2.5% and about 75% by weight of the aqueous binder and that the weight ratio phosphate / magnesium is between about 1 and about 4. The amounts of magnesium and phosphate suitable for the purposes of the invention are respectively expressed in magnesium ions and phosphate ions.

 Preferably, the magnesium proportion is from about 5 to about 50% by weight of the aqueous binder. The preferred phosphate / magnesium weight ratio is from about 1.5 to about 3.5.

 According to a variant of the invention, it is advantageous to add to the mixture a certain amount of metal sulphide, such as sodium, potassium, calcium or iron sulphide, of between about 0.1% and about 10%. by weight of the aqueous binder, in order to improve its retention properties with respect to pollutants.

 It is also possible according to another variant, to add a setting accelerator aqueous binder, such as calcium chloride, sulfate or nitrate, sodium or potassium silicate, sodium or potassium aluminate in an amount of from about 0.1% to about 10% by weight of the aqueous binder.

 In another embodiment, clay may be added to the mixture in an amount of from about 0.1% to about 25% by weight of the aqueous binder.

 It is also possible to add silica fume to the mixture in an amount of from about 0.1% to about 50% by weight of the aqueous binder.

 In another aspect, the invention relates to a method of solidifying and stabilizing used batteries, which uses the aqueous binder described above.

 According to the invention, it is first necessary to grind the batteries in order, by shredding their protective envelope, to be able to treat them chemically.

 In a second step, it is possible to carry out a magnetic stripping of the ground material obtained. Indeed, the envelope itself represents, depending on the type of battery, 25 to 55% of the total weight and consists of 60 to 85% of steel and 15 to 40% of plastic.

 Then, in a third step, the ground material, whether or not defreened, is incorporated in the aqueous binder as defined above.

 Advantageously, 100 kg of ground material can thus be for example brought into the presence of about 17.5 to 150 kg, preferably about 20 to 100 kg of the aqueous binder.

 The present invention also relates to the solid product obtainable by carrying out the process described above. It is understood that the product thus obtained is composed mainly of crushed piles which is trapped in a compact continuous and homogeneous matrix having good mechanical strength and capable of retaining soluble pollutants such as salts or heavy metals.

 The invention will now be illustrated with the aid of the following examples given in a non-limiting manner.

Example 1
To stabilize and solidify a ton of unreinforced pile material, it is intimately mixed with a composition having the following formula:
260 kg slag cement powder
Calcined dolomite 90 kg
Monosodium phosphate 50 kg
Calcium nitrate 25 kg
Water 375 kg
After 28 days of cure, the performances obtained are as follows:
* Compressive strength 9.25 MPa
* Analysis of the leachate of the solidified block obtained according to the NF standard
X31211
pH 11.8
Soluble fraction 2.45%
(ratio of the solubilized part to the dry weight of the leached sample)
* Analysis of heavy metals (in mgA (g relative to the gross weight of
the leached sample)
As <1.5 mg / kg
Cr6 + <0.3 mg / kg
Cr tot. <0.3 mg / kg
Cd <0.6 mg / kg
Hg <1.5 mg / kg
Ni <0.3 mg / kg
Pb <1.5 mg / kg
Zn 4.5 mg / kg
The performances obtained make it possible to meet all the criteria for admission to the elimination center.

Example 2
To stabilize and solidify a ton of unreinforced pile material, it is intimately mixed with a composition having the following formula:
260 kg slag cement powder
Calcined dolomite 90 kg
Monocalcium phosphate 50 kg
Calcium nitrate 25 kg
Silica fume 75 kg
Water 385 kg
After 28 days of cure, the performances obtained are as follows:
* Compressive strength 9.75 MPa
* Analysis of the leachate of the solidified block obtained according to the NF standard
X31211
pH 11.7
Soluble fraction 2.02%
(ratio of the solubilized part to the dry weight of the leached sample)
* Analysis of heavy metals (in mg / kg relative to the gross weight of
the leached sample)
As <1.5 mg / kg
Cr6 + <0.3 mg / kg
Cr tot. <0.3 mg / kg
Cd <0.6 mg / kg
Hg <1.5 mg / kg
Ni <0.3 mg / kg
Pb <1.5 mg / kg
Zn 3.45 mg / kg
The performances obtained make it possible to meet all the criteria for admission to the elimination center.

Example 3
In order to stabilize and solidify a tonne of debrunted pile mill, it is intimately mixed with a composition having the following formula:
Slag-based cement powder 700 kg
Magnesium oxide 100 kg
Phosphoric acid 80 kg
Water 485 kg
After 28 days of cure, the performances obtained are as follows:
* Compressive strength 12.35 MPa
* Analysis of the leachate of the solidified block obtained according to the NF standard
X31211
pH 10.3
Soluble fraction 1.1%
(ratio of the solubilized part to the dry weight of the leached sample)
* Analysis of heavy metals (in mg / kg relative to the gross weight of
the leached sample)
As <1.5 mg / kg
C + <0.3 mg / kg
Cr tot. <0.3 mg / kg
Cd <0.6 mg / kg
Hg <1.5 mg / kg
Ni <0.3 mg / kg
Pb <1.5 mg / kg
Zn 1.5 mg / kg
The performances obtained make it possible to meet all the criteria for admission to the elimination center.

Example 4
In order to stabilize and solidify a tonne of debrunted pile mill, it is intimately mixed with a composition having the following formula:
Slag-based cement powder 700 kg
Magnesium oxide 100 kg
Monosodium phosphate 100 kg
Calcium nitrate 25 kg
Clay 25 kg
Water 425 kg
After 28 days of cure, the performances obtained are as follows:
* Compressive strength 12.3 MPa
* Analysis of the leachate of the solidified block obtained according to the NF standard
X31211
pH 11.55
Soluble fraction 1.85%
(ratio of the solubilized part to the dry weight of the leached sample)
* Analysis of heavy metals (in mg / kg relative to the gross weight of
the leached sample)
As <1.5 mg / kg
Cr6 + <0.3 mg / kg
Cr tot. <0.3 mg / kg
Cd <0.6 mg / kg
Hg <1.5 mg / kg
Ni <0.3 mg / kg
Pb <1.5 mg / kg
Zn <1.5 mg / kg
The performances obtained make it possible to meet all the criteria for admission to the elimination center.

Claims (14)

 Aqueous binder, consisting of a mixture comprising (a) a slag cement powder, (b) a magnesium ion source, (c) a phosphate ion source and (d) water, wherein the magnesium proportion is from 2.5% to 75% by weight of the aqueous binder and the weight ratio of phosphate to magnesium is from 1 to 4.  The aqueous binder of claim 1, wherein the slag cement is blast furnace cement or slag and ash cement.  An aqueous binder according to claim 1 or 2, wherein said cement powder has a particle size of less than 200 μm.  4. Aqueous binder according to one of claims 1 to 3, wherein the magnesium ion source is a magnesium oxide or hydroxide, magnesium lime or a magnesium salt.  5. aqueous binder according to one of claims 1 to 4, wherein the source of phosphate ions is phosphoric acid or sodium phosphate, potassium, calcium or magnesium.  6. aqueous binder according to one of claims 1 to 5, wherein the proportion of magnesium is 5% to 50% by weight of the aqueous binder.  7. aqueous binder according to one of claims 1 to 6, wherein the weight ratio phosphate / magnesium is between 1.5 and 3.5.  The aqueous binder according to one of claims 1 to 7, wherein the mixture further comprises from 0.1% to 10% by weight, based on the aqueous binder, of a metal sulfide.  The aqueous binder according to one of claims 1 to 8, wherein the mixture further comprises from 0.1% to 10% by weight, based on the aqueous binder, of a setting accelerator of said binder.  The aqueous binder according to one of claims 1 to 9, wherein the mixture further comprises from 0.1% to 25% by weight, based on the aqueous binder, of clay.  The aqueous binder of one of claims 1 to 10, wherein the mixture further comprises from 0.1% to 50% by weight, based on the aqueous binder, of silica fume.  12. Process for the solidification and stabilization of used batteries, consisting of  a) grind used batteries,  b) optionally magnetically remove the ground material obtained, and  c) incorporating the ground material obtained in step a) or in step b) in the aqueous binder according to one of claims 1 to 11.  13. The method of claim 12, wherein the weight ratio between the aqueous binder and the ground material is between 0.175 and 1.5.  14. Stacked and stabilized used batteries obtainable by the process according to claim 12 or 13.