EP4314360A1

EP4314360A1 - Pyrometallurgical method for recycling shredded material of waste from the production of new and defective or end-of-life batteries for electric vehicles or portable li-ion batteries

Info

Publication number: EP4314360A1
Application number: EP22717230.1A
Authority: EP
Inventors: Jean-Luc Roth
Original assignee: Eco'ring
Current assignee: Eco'ring
Priority date: 2021-03-26
Filing date: 2022-03-25
Publication date: 2024-02-07
Also published as: US20240191316A1; CA3213335A1; WO2022200747A1

Abstract

The invention relates to a pyrometallurgical method for recycling shredded material of end-of-life Li-ion electric vehicle batteries, and/or waste from the production of these new and defective batteries, and/or portable Li-ion batteries. The method involves adding iron, melting by adding energy, separating a slag, carrying out an oxidising treatment and separating a second slag.

Description

Title of the invention: Pyro-metallurgical process for recycling shredded waste from the production of new and defective or used batteries from electric vehicles or portable Li-ion type batteries.

Technical area

[0001] The batteries of electric or portable vehicles of the Li-ion type include valuable elements that it is important to properly recycle, Copper Cu, Aluminum Al (2 metals present in metallic form), Nickel Ni, Cobalt Co, Manganese Mn and of course Lithium - the latter in the form of combined oxides.

[0002] In most known sectors, the recycling of these batteries - whether they are scrap or waste from the production of new batteries, used batteries or defective new batteries - goes through a grinding stage (crusher of the shredder type), which separates Copper and Aluminum (metals) in good proportions, and produces a "black mass" bringing together the other metals as well as a large proportion of carbon, in elemental form (fixed C ) or combined, in plastics and oils similar to hydrocarbons. It is specified that during the production of new batteries, waste is produced such as waste from cutting anode and cathode coils, scrap anodes and cathodes, anode and cathode assemblies defective assemblies referred to as bundles, defective anode and cathode assemblies packaged without solvent referred to as dry cell and defective pouches with solvents. By way of example, a synoptic of the production of waste in the manufacture of new batteries is attached.

[0004] Several solutions are currently being proposed and tested to enhance this black mass, most often by hydrometallurgical means—and in several stages.

[0005] This document proposes a pyro-metallurgical recovery solution going through 3 stages:

- An agglomeration of the black mass (pelletizing, briquetting, or extrusion) - with the addition of iron ore or oxidized or non-oxidized scrap - the general notion of iron source is present in the text - and an appropriate binder

- A carburizing fusion in a rotating converter (or another type of converter equipped with a stirring device), making it possible to separate the Lithium in a slag and dust comprising lithium oxide Li20, decanted before pouring, easily recoverable in the current production channels for this metal

- Oxidizing refining in the same converter, or in a second specialized converter, leading to an alloy of the FeNiCo type containing approximately 50% (Ni+Co), which can be used in the production of high-strength steels (in particular steels used in aeronautics), and a slag rich in manganese, iron and lime, which constitutes an excellent raw material for furnaces for the production of Ferro-Manganese.

[0006] Table of Contents

1. Problem to solve

1.1 Constitution of electric vehicle batteries

1.2 Recovery channel - Objective of the proposed process

1.3 State of the art

1.4 Principle of the proposed process

2. Example

2.1. Composition of the “Black Mass + Fe Ore” mix

2.2. Material balances

2.2.1. Merger

2.2.2. Refining

2.3. Rewarding opportunities

2.4. Case of a Low Phosphorus Black Mass

3. Summary

[0007] 1. Problem to be solved

[0008] 1.1 Constitution of electric vehicle batteries

[0009] Electric vehicle batteries are of 2 types:

- NiMH (Nickel Metal Hydride) type batteries

- Li-ion type batteries

[0010] It is this last type that tends to prevail at present. The possibility and efficiency of recycling Li-ion batteries is a major challenge in the development of electric vehicles or portable applications (telephony, computers, electric bicycles, etc.).

[0011] The recycling of Li-ion batteries gives rise to significant developments among the manufacturers of these batteries, and multiple alliances have recently been formed for this purpose. We propose in what follows a solution combining grinding and a pyrometallurgical process for the complete recycling of these Li-ion batteries.

The principle and the exact constitution of these Li-ion batteries are widely described elsewhere, we will simply recall the size of these batteries, which weigh from a few grams (button type) to several hundred kg, as suggested. in figure 1 above, and to give the overall composition in table 1.

[0014] [Fig. 1]: Overview of an electric vehicle battery [0015] [Table 1] Composition - type of a Li-ion battery

0016] The active core of the battery (cathode / anode / electrolyte) is mainly composed of oxides and/or phosphates of the type LiNi02, LiCo02, LiMn02, LiFeP04, graphite and fluoride LiPF6 for the electrolyte, dissolved in a organic solvent.

[0017] More specifically, the production of new batteries is accompanied by the production of several levels of waste or scrap, such as waste from cutting anode and cathode coils, scrap anodes and cathodes, defective anode and cathode assemblies referred to as bundles, defective anode and cathode assemblies bagged without solvent referred to as dry cell and defective solvent bags.

[0018] By way of example, Table 2 below presents a synoptic of the production of this waste in the manufacture of new batteries, at different stages.

[0019] [Table 2] Synoptic of the production of waste in the manufacture of Li-ion batteries Anode rolls Cathode rolls

(Copper sheet on which is deposited (Aluminum sheet on which is a layer of graphite) deposited a layer of mixed oxides Li -

The valuable elements that it is crucial to properly recycle because of the environmental and energy cost, are Copper Cu, Aluminum Al (2 metals present in metallic form), Nickel Ni, Cobalt Co, Manganese Mn and of course lithium.

[0020] We note the potentially significant presence of Phosphorus P, a steel pollutant, and of Fluorine F, a source of corrosion of the refractories and of the steels that make up the treatment installation.

[0021] 1.2 Recovery sector - Objective of the proposed process [0022] Recycling of large Li-ion batteries mostly involves complete crushing (Figure 2)

[0023] [Fig. 2] Li-ion batteries in the grip of a crusher

[0024] This grinding and the separation tools that follow make it possible to effectively separate the metals present in metallic form - Al, Cu and Fe (steel). The remainder is crushed and/or recovered in the form of a muddy mass, consisting of fines of less than 2 mm, and an organic liquid, mass called "black mass"

[0025] The objective of complete recycling is to recover all the elements of value, in usable forms. This objective can be achieved by different types of processes - hydrometallurgical or pyro-metallurgical. The entire sector is shown schematically in Figure 3 below.

[0026] [Fig. 3] Overall chain of Li-ion battery recycling [0027] 1.3 State of the art

[0028] Currently, it seems that most companies or groups that have embarked on the recycling of Li-ion batteries are experimenting with or moving towards a scheme as shown in Figure 3, with grinding and Upgrading the Black Mass by Hydrometallurgical Processes An example of analysis of a black mass is given in Table 3 below.

[0030] Black mass analysis (% mass, dry)

[0031] [Table 3]

[0032] It should be noted that:

- This analysis is representative of a "mix" of batteries from various sources, and therefore containing various active compounds, and in particular a large proportion of batteries with active compounds containing Phosphorus P (e.g. LiFeP04)

- If one starts from used batteries of the same type free of Phosphorus or with a low P content, in particular if batches of defective new batteries without P are recycled on an installation, the P content will be very low or nothing.

- There are still significant residual contents of Copper Cu and Aluminum Al, present in metallic form, and therefore incompletely eliminated in the grinding step and consecutive separation

- The high phosphorus content must be eliminated as best as possible from the metal to be recovered.

We will not make here a comparison of the proposed sectors, but we can simply say that in this case the hydro-metallurgical processes present a priori heavy handicaps compared to a pyro-metallurgical process

- They require a large number of steps (at least as many as the metals to be separated);

- they are very large consumers of chemical reagents that are dangerous for humans and the environment, and expensive;

- they will lead to more ultimate waste (polluted acid solutions) to be neutralized and placed in storage.

[0034] This is provided that a pyro-metallurgical solution can achieve the objective of extracting all valuable metals into a usable form.

[0035] 1.4 Principle of the proposed method

[0036] Thus, there is proposed a method for recovering black mass from lithium batteries, the method comprising adding iron ore or oxidized or non-oxidized scrap metal to the black mass to obtain a mixture, a melting of the mixture by supplying energy to obtain a carburized metal bath, a separation of a first slag to obtain a purified metal bath, then an oxidizing treatment of the purified metal bath and the separation of a second slag, to obtain a ferroalloy.

[0037] The ferroalloy obtained is rich in Nickel and Cobalt, the metals to be used in the manufacture of high-strength steels. The first slag is rich in lithium in the form of Li20 oxide, and the second slag is rich in manganese and lime when lime is added during the oxidizing treatment, in particular to extract the Phosphorus P from the ferroalloy. It is advantageous to separate the two slags independently of each other to allow independent recovery of lithium and manganese. They are separated by pouring after settling, the first before the oxidizing treatment step, and the second after the oxidizing treatment step. The presence of iron ore or scrap, which is another source of iron, makes it possible to work at lower temperatures, and to minimize the loss of nickel and cobalt in the form of oxides.

In general, and as is the case in the analysis of the black mass given by way of example, it contains enough carbon to ensure the reduction of the oxides, and the carburization of the metal obtained, at height of 3~4%C in the carburized ferroalloy. If this is not the case, carbon is introduced in the form of anthracite or a substitute carbonaceous material, in order to melt the mixture. This ensures that for sure the fusion is carburizing, that is- that is, reducing, so that the reducible metals, namely cobalt, iron and nickel, but also copper and manganese, are effectively reduced.

[0039] Advantageously, an agglomeration into pellets or briquettes or an extrusion is carried out before melting. This allows bulk storage and conveyor transport to the converter, and avoids loss of material by flight during loading.

[0040] Advantageously, the melting is carried out in a rotating converter or one equipped with a stirring device. This makes it possible to homogenize the mixture during its fusion.

Advantageously, the addition of iron ore to approximately 94% iron oxide Fe203 in the proportion ½ quantity of iron ore for 1 quantity of the black mass of the battery is carried out on the black mass of the battery to obtain the mixture to melt. Depending on the composition of the black mass, this proportion is varied to target a quantity of iron in the ferroalloy close to 50% by weight.

[0042] Advantageously, the black mass comes from a crushed or disassembled lithium battery. [0043] Advantageously, hydrated lime is added as a binder to facilitate the agglomeration of the black mass and the iron ore or scrap metal, at least.

Advantageously, quicklime, pure or not, is added during the oxidizing treatment. [0045] Advantageously, a continuous production campaign is carried out, during which a fraction of the metal bath resulting from the oxidizing treatment after separation of the second slag is the subject of an addition of carbon and is used to receive black mass. and iron ore or scrap newly introduced, and constitute the mixture which is the subject of the fusion and the obtaining of the carburized metal bath.

The proposed method comprises 3 steps:

- An agglomeration of the black mass (pelletizing, briquetting, or extrusion) - with an appropriate binder and iron ore or scrap, oxidized or not oxidized,

- A fuel-reducing fusion in a rotary converter (called TBRC, Top Blown Rotary Converter - rotary converter with blowing from the top) or possibly in a fixed converter whose bath is agitated by another means, in particular by gas injection ( hydrocarbon or hydrogen) in the bottom of the reactor

- Oxidizing refining in the same converter, or in a second specialized converter.

The process is shown schematically in Figure 4.

[0047] [Lig. 4] Diagram of the proposed pyro-metallurgical process

The principle of the process, and the objectives of each step, can be summarized as follows: 1) The agglomeration of the black mass 100 with a binder and an addition of an iron source (see later) (binder, iron ore 110) aims to obtain a product strong enough to be stored in bulk and then in a hopper , and to be continuously loaded into the converter by a conveyor. There is agglomeration / ex: bricklaying El, then semi-continuous loading 120.

2) Carburizing E2 or carburizing-reducing fusion in a top-blowing rotary converter (TB RC) equipped with a lance and/or a gas (hydrocarbon or hydrogen)/oxygen burner and containing the FeNiCoMnC alloy 130 or the FeNiCo alloy from the previous oxidizing treatment which is recarburized into FeNiCoC, must make it possible, by using the carbon contained in the black mass, to reduce the oxides of reducible metals (Ni, Cu, Co, Fe, Mn), and recover them with good yield in a carburized metal alloy, called FeNiCoMnC; in this step, the aim is to separate the lithium in a slag 140 and dust rich in Li (in the form of Li20) and moreover to partially desulfurize and dephosphorize the metal obtained. The energy input necessary for the very endothermic reduction reactions is provided mainly by the combustion of the CO gas resulting from the oxide reduction reactions, and by the combustion of the excess carbon (in the form of fixed C and HC hydrocarbons) by an injection of oxygen; depending on the composition of the black mass, an additional energy supply may be necessary, by a gas (hydrocarbon or hydrogen)-oxygen burner, or even using an electrical energy source, taking the form of an arc electric.

3) E3 oxidative refining by injection of oxygen via an oxygen lance 220 in the figure and with a supply of powdered or granulated lime, then makes it possible to extract from the FeNiCoMnC alloy, the Manganese, the Carbon, and a large part of Phosphorus, in order to obtain, on the one hand, a FeNiCo 150 alloy which can be used in the manufacture of certain high-alloy steels, and on the other hand, a slag rich in Manganese and lime 160, which can be used in the manufacture of FerroManganese.

In this step, the presence of iron in a large proportion makes it possible to "protect" the metals of greater value (Ni and Co) The alloy is cast either in a ladle or in ingots 230 on an ingot machine - as presented in figure 4 - and the slag is poured into a ladle, from where it can optionally be granulated or poured into a heap to allow its natural cooling or accelerated by sprinkling water.

[0049] In practice, the fusion of the briquettes of the black mass + iron ore or iron source mixture such as scrap + carbon (agglomerated with the aid of a binder, e.g. lime hydrated) follows the following sequence, summarized in the simplified process diagram in Figure 5 below.

[0050] [Fig. 5]: sequence of the complete melting - refining process

We start in the rotary converter with a "foot of metal bath" of 1/3 of the capacity of the rotary converter, and having the analysis of the targeted FeNiCoC ferroalloy; in a continuous production campaign, this bottom of the bath comes from part of the previous charge, which will have been recarburized by adding carbon and stirring the bath by rotating the converter

The briquettes of “black mass + iron ore + binder are continuously loaded, with short interruptions to pour the excess slag by overflow, until a quantity of metal corresponding to the nominal capacity of the converter is obtained; the melting takes place continuously with the energy input from the “oxygas” burner and the “postcombustion” (combustion of the CO resulting from the reduction reactions by injecting additional oxygen)

After complete casting of the slag, the refining (extraction of P and Mn) of the metal is started by a continuous injection of oxygen and lime, until the target P content is obtained (generally lower at 0.1%P); then the remaining FeNiCo metal is poured, keeping a bath foot of 1/3 of the capacity of the reactor, to start the following sequence

The proportions and compositions of the filled materials, metallic and slag baths obtained are given in the appendix.

[0055] 2. Example

[0056] 2.1. Composition of the “black mass + Fe Ore” mix

To the black mass of composition given in Table 3, standard iron ore containing 94% iron oxide Fe203 is added, in the proportion 1 t BM + 0.5 t Fe ore. This results in a mixture ( 'mix') of the composition shown in Table 4 below.

[0058] [Table 4] Composition of the black mass + Fe ore mix

[0059] 2.2. Material balances [0060] 2.2.1. Merger

The melting step is carried out in the converter, according to the material balance presented in table 5a below.

[0062] [Table 5a] Material balance of the fusion

The fusion therefore gives, for 1 1 of black mass, 451 kg of FeNiCoMnC alloy, with the composition indicated in Table 4; an acceptable S content (0.1%) is observed, but the P content (0.56%) is much too high for use as an alloy raw material. in the carburized alloy. 150 kg of slag rich in Li (in the form of Li20); - with the recycling of the dust, a large part of the Li is finally recovered in the slag 13 kg of dust recovered in the gas treatment line by filtration, which will be recycled in the input mixture to be agglomerated.

Alternatively, the melting step is carried out in the converter, according to the material balance presented in Table 5b below, which indicates an addition of lime CaO and magnesia MgO, so as to obtain the following basicity ratios in the slag from the melting step: single basicity CaO/Si02 ~1.5, and overall basicity (Ca0+Mg0)/(Si02+A1203) from 0.7 to 0.8. [0065] [Table 5b] Material balance of the fusion

The fusion therefore gives, for 1 ton of black mass, 448 kg of FeNiCoMnC alloy, again with the composition indicated in Table 4; there is again an acceptable S content (0.1%), but the P content (0.63%) is much too high for use as an alloy raw material 119 kg of slag containing part - about 1 /3 - Lithium (in the form of 10-20% of Li20 oxide) † 57 kg of dust recovered in the gas treatment line by filtration, which contains about 2/3 of Lithium in the form of oxide Li20, which will be extracted from it, for example, by hydrometallurgy. The remainder, which contains valuable metals, especially Ni and Co., will be recycled into the input mixture to be agglomerated.

The energy input for this fusion is provided by the combustion of Carbon (graphite C and hydrocarbons HC), by means of a supply of gaseous oxygen, injected by means of a lance into the metal / slag bath. The quantity of oxygen injected is around 260 Nm3/t of black mass (200 to 300 Nm3 per ton of black mass depending on the exact composition).

[0067] 2.2.2. Refining

The refining step consists in extracting the manganese, an easily oxidizable metal, by injecting oxygen, at the same time as the carbon, a large part of the phosphorus, and a part of the iron will be eliminated. A summary of this refining step is presented in Table 6a. In terms of energy, all these oxidation reactions are largely exothermic, and will more than cover the losses of the reactor.

[Table 6a] Material balance of refining

The refining therefore gives, for 1 1 of black mass, 312 kg of FeNiCo alloy with the composition indicated in Table 5; there are acceptable contents of S (0.069%) and P (0.081%)

We note in the right column the yields of the metals recovered in the FeNiCo alloy - distinguishing the yield during refining, and the overall yield of the element, starting from the black mass. 257 kg of slag rich in Mn, Fe and lime 14 kg of dust whose composition is close to that of slag, into which they can be incorporated before pouring.

Alternatively, a summary of this refining step is presented in Table 6b. Refining gives, for 1 t of black mass, 311 kg of FeNiCo alloy with the composition indicated in Table 5; we again observe acceptable levels of S (0.083%) and P (0.091%) 262 kg of slag rich in Mn, Fe and lime 448 kg of dust whose composition is close to that of slag, to which they can be incorporated before casting.

[Table 6b] Material balance of refining

[0072] 2.3. Rewarding opportunities

The 3 products obtained have guaranteed outlets, and the uses can be specified:

- The FeNiCo alloy with 48 or 49% Fe, 35% Ni, 14% Co can be advantageously used in the production of high alloy steels of the Maraging type, used in aviation, and which typically contain 17~19% Ni , 8~12%Co. It can therefore replace Ni and Co inputs in the form of ferroalloys.

- Slag and dust rich in Li20 constitute a very rich Li ore that can easily be incorporated into the extraction and production of Li by hydrometallurgy.

- FeO-MnO-CaO slag containing ~27%MnO (~21%Mn) will be a raw material of choice for carbothermic reduction furnaces producing ferromanganese. In these furnaces, 40% Mn ores are commonly used, but large quantities of CaO lime are added to them, because a high basicity of the slag obtained favors the Manganese yield. The FeO-MnO-CaO slag resulting from the upgrading of the black mass will therefore replace both a Manganese ore, an addition of CaO lime, and an addition of Iron.

[0074] 2.4. Case of a low phosphorus black mass

A phosphorus-free or low-phosphorus black mass has a similar typical composition, an example of which is given in Table 7 below.

The phosphorus content here is 10 times lower than in the standard black-mass. [0077] [Table 7] Typical composition of a low phosphorus black-mass

[0078] A usable die is of course the die described for high phosphorus black-mass, comprising 2 stages (melting and refining) and ultimately giving a low phosphorus FeNiCo alloy that can be used in the development of high-alloy high-grade steels. Ni and Co contents.

[0079] The results of this sector are collated in Tables 8a and 8b below.

[0080] [Table 8a] Melting and refining balances for low phosphorus black mass

[0081] [Table 8b] Melting and refining balances for low phosphorus black mass

However, it appears that the main poison element for the recycling of high-value metals (Ni and Co), namely phosphorus, is in this case eliminated from the melting step, where it is lowered to less than 0.1% P in the FeNiCoMnC ferroalloy.

Admittedly, the FeNiCo alloys of the “Maraging” type have low Mn and C contents in their standard analysis (often less than 0.2% each). However, possibilities of direct use of the FeNiCoMnC ferroalloy may exist, either by introducing them in a preliminary phase of the development (where Mn and C will be eliminated), or for versions derived from these types of ferroalloy, tolerating higher contents. of Mn and C.

[0084] 3. Summary

Li-ion type batteries include as valuable elements that it is crucial to properly recycle, Copper Cu, Aluminum Al (2 metals present in metallic form), Nickel Ni, Cobalt Co, Manganese Mn and of course Lithium - the latter in the form of combined oxides.

[0086] In the known sectors, the recycling of these batteries - whether waste from the production of used batteries or defective new batteries - goes through a grinding stage (shredder-type grinder), which separates into good proportions Copper and Aluminum (metals), and produces a "black mass" bringing together the other metals, as well as a significant proportion of carbon, in elemental (fixed C) or combined form, in plastics and oils assimilated to hydrocarbons.

[0087] Several solutions are currently being proposed and tested to upgrade this black mass, most often by hydrometallurgical means—and in several stages.

[0088] This document proposes a pyro-metallurgical recovery solution going through 3 stages:

- An agglomeration of the black mass (pelletizing, briquetting, or extrusion) - with addition of iron ore and an appropriate binder

- A carburizing-reducing fusion in a rotating converter (or another type of converter equipped with a stirring device), allowing the separation of Lithium in a slag and dust rich in Li20, very recoverable in the current elaboration sectors of this metal. Additions of lime and magnesia to the mixture before the carburizing fusion make it possible to obtain, after overflow, a first fluid slag, with as basicity indices: simple basicity b = CaO/Si02, of the order of 1.5, and overall basicity B = (Ca0+Mg0)/(Si02+Al2O3), of the order of 0.7-0.8. This first slag contains lithium.

The main energy input for fuel fusion is generally the combustion of the carbon in the black mass by injecting gaseous oxygen into the bath.

Claims

[Claim 1] Process for upgrading black mass (100) from lithium batteries, characterized in that the process comprises adding (El) a source of iron (110) to the black mass to obtain a mixture, a fuel melting (E2) of the mixture by supplying energy to obtain a carburized metal bath (130), a separation of a first slag (140), then an oxidizing treatment (E3) of the carburized metal bath thus purified, and the separation of a second slag (160) to obtain a ferroalloy (150).

[Claim 2] Process for upgrading black mass according to claim 1, characterized in that the carbon is introduced primarily by the graphite contained in the black mass, and, if a supplement is necessary, in the form of anthracite or a substitute carbonaceous material, for the purpose of melting the mixture.

[Claim 3]. Process for upgrading black mass according to Claim 1 or Claim 2, characterized in that an agglomeration into pellets or briquettes or an extrusion is carried out before melting.

[Claim 4] Process for upgrading black mass according to one of Claims 1 to 3, characterized in that the fusion is carried out in a rotating converter (200) or equipped with a stirring device.

[Claim 5]. Process for upgrading black mass according to one of Claims 1 to 4, characterized in that an addition of iron ore as source of iron to approximately 94% iron oxide Fe203 on the black mass of battery to obtain the mixture , is carried out in the proportion ½ amount of iron ore for 1 amount of black battery mass.

[Claim 6] Process for upgrading black mass according to one of Claims 1 to 5, characterized in that the black mass comes from crushed or dismantled lithium batteries.

[Claim 7] Process for upgrading black mass according to one of Claims 1 to 6, characterized in that hydrated lime is added as a binder to facilitate the agglomeration of the black mass and iron ore as a source of iron , at least.

[Claim 8] Process for upgrading black mass according to one of Claims 1 to 7, characterized in that quicklime is added during the oxidizing treatment.

[Claim 9] Process for upgrading black mass according to one of Claims 1 to 8, characterized in that a continuous production campaign is carried out, during which a fraction of the metal bath resulting from the oxidizing treatment after separation of the second slag is carbon-added and used to receive newly introduced black mass and iron source and form the mixture that is smelted to form the carburized metal bath .

[Claim 10] Process for upgrading black mass according to one of Claims 1 to 9, characterized in that the source of iron is iron ore.

[Claim 11] Process for upgrading black mass according to one of Claims 1 to 9, characterized in that the source of iron is scrap metal, oxidized or non-oxidized.

[Claim 12] Process for upgrading black mass according to one of Claims 1 to 11, characterized in that additions of lime and magnesia to the mixture before the fuel fusion make it possible to obtain a first slag (140) with as indices of basicity: simple basicity b = CaO/Si02, of the order of 1.5, and overall basicity B = (Ca0+Mg0)/(Si02+A1203), of the order of 0.7-0.8.