Field of the Invention

[0001] The present invention relates to a process for zeolite production.

[0002] More particularly, the process of the present invention provides, in one form, for the production of zeolite from waste aluminosilicate from the lithium mining industry.

Background Art

[0003] Lithium and its compounds have been used historically in diverse applications, including batteries, lubricating greases, pharmaceuticals, glass, ceramics, and metallurgy (Choubey et al., 2016; Collins et al., 2020; Han et al., 2018; Liu, Z. et al., 2019; Meshram, P. et al., 2014; Sun et al., 2014). For example, high capacity lithium batteries are already prevalent in mobile devices and are strong candidates for renewable energy storage (Flexer et al., 2018). Substantial growth of lithium battery use is expected as demand for electric vehicles increases (Setoudeh et al., 2020). Lithium is largely extracted from hard rock ores (lithium minerals such as spodumene, petalite and lepidolite) (Han et al., 2018) and aqueous resources such as lithium rich brines or salt lakes (Flexer et al., 2018). At present, the majority of lithium production around the world belongs to: six mineral operations in Australia, two brine operations each in Argentina and Chile, and one brine and one mineral operation in China (Survey, 2020). Indeed, Australia is currently the world’s largest producer of lithium (Flexer et al., 2018; Vikstrom et al., 2013). Spodumene is the favoured resource as lepidolite and petalite typically contain a high fluoride content (Vikstrom et al., 2013).

[0004] With increasing demand for lithium there comes an increased production of associated waste materials. The aluminosilicate based waste product from hard rock refining is generically termed “lithium slag” or spodumene leachate residue (SLR) if spodumene is the mineral source (Zampori et al., 2012). SLR is the solid waste formed after: (1) heat treatment at high temperatures to transform a- spodumene to the more active b-spodumene; and (2) leaching with sulphuric acid to recover lithium ions. The general formula for SLR is HAIS12O6 and this material is commonly stored in the outdoors, bringing the potential for environmental damage (Chen et al., 2012). Consequently, SLR has been used as cement clinker, in concrete, as a raw material for ceramic glazed tiles and in activated clays (Han et al., 2018). However, the utilisation rate is only about 10 % (Beushausen et al., 2012) which means there is a clear need to discover alternate uses for SLR.

[0005] Use of SLR to make synthetic zeolites appeals as an avenue of research as this makes use of the high aluminosilicate content of SLR. Zeolites are typically microporous or mesoporous with the general composition: Mx/n (AIO2) x (S1O2) y ZH2O where M is the cation that compensates the negatively charged framework, n is the cation valency, y/x is the Si/AI ratio, and z is the water content. Zeolite A or LTA is the predominant zeolite used by industry on a mass basis (making up 73 % of global production (Ayele et al., 2016)) due primarily to use in laundry detergents as a water softener (Meshram, S.U. et al., 2014).

[0006] The concept of transforming waste and naturally occurring aluminosilicates to higher value products such as zeolites has been studied in relation to development of green synthesis methods (Liu et al., 2014; Pan et al., 2019). Importantly, due to the poor reactivity of waste or natural aluminosilicates an additional activation stage is commonly applied. For example, thermal treatment of SLR has been studied in relation to construction industry utilisation (Liu, Z. et al., 2019). It was discovered that the amorphous content increased from ca. 17 to 51 % upon heating at 700 °C for 2 h. Whereas, Zhuang et al. (Zhuang et al., 2014) reported that hydroxide dissolution followed by hydrothermal synthesis produced a zeolite LTA/Faujasite mixture from lithium slag. Fusion pre-treatment of aluminosilicate waste materials to activate the silica and alumina species is commonly used. The basic premise is to heat a mixture of waste and sodium hydroxide at temperatures above the melting point of NaOH for several hours. Hence, Chen et al. (Chen et al., 2012) fused lithium slag with sodium hydroxide at 600 °C for 4 h and then aged and hydrothermally reacted the resultant solid at 95 °C for 8 h to make zeolite. [0007] As noted above, the need for activation of aluminosilicate waste materials presents as a key difference to the majority of current commercial zeolite synthesis approaches in which aluminosilicate gels are created from monomeric silicates and aluminates. Therefore, efforts have focussed on developing lower cost means of activating waste and natural aluminosilicates. High temperature fusion with NaOH is viewed as too expensive to be industry relevant (Ojumu et al., 2016). Bao and co-workers published a series of articles detailing the activation of rectorite and kaolin clay using a process termed “High Concentration Alkali Solution” (HCAS) (Li et al., 2012; Liu et al., 2015; Yue et al., 2014; Yue et al., 2015). The basis of this approach was hydrothermal reaction of the clay with high molarity (5 to 15 M) NaOH solutions at temperatures of 200 °C or higher. The resultant solid was then separated from solution and reacted under appropriate conditions to make zeolites such as LTA, ZSM-5 and USY. Liu et al. (Liu, H. et al., 2019) compared thermal, alkali fusion and HCAS activated rectorite upon the synthesis of Ti-ZSM-5 zeolite. It was found that titanium species were partially incorporated in the lattice framework of the zeolite when employing the alkali fusion or HCAS methods, whilst with thermal activation only extra framework titania was recorded. Consequently, the catalytic activity of the titanium incorporated ZSM-5 was greater for 1-octene hydro isomerisation and aromatization. However, the inventors of the HCAS process have indicated that this technology is costly in terms of the amount of water to be evaporated and difficult to scale-up as it is a batch process.

[0008] Miao et al. (Miao et al., 2016) have described the transformation of potassic rocks to low sodium zeolite X (LSX) using the sub-molten salt approach. Notably, the abovementioned fusion activation strategy is conducted at temperatures above the melting point of, for example, sodium hydroxide whereas the sub-molten approach is conducted at a temperature less than the melting point of, again for example, sodium hydroxide. A mixture of powdered potassic rock, potassium hydroxide, and water was heated with agitation in the temperature range 180 and 200 °C for up to 7 h. The mass concentration of KOH was said to be critical, with a value of 75 % recommended as the resultant product exhibited only peaks in the X-ray diffraction (XRD) patterns ascribed to potassium hydroxide. Yang et al. (Yang et al., 2017) more recently described how to activate kaolin under relatively mild conditions in order to make them amenable for conversion into zeolite LTA and zeolite Y. The strategy was termed “Quasi-Solid Phase Activation Process (QSP)”. Initially, kaolin was kneaded with sodium hydroxide and a small fraction of water was added. Subsequently, this material was extruded into shapes 1.5 mm in diameter and 2 to 3 cm in length. The extrudate was finally heated to between 60 and 100 °C for 30 min in a belt type calcination oven. The principal advantages relative to the HCAS approach were: (1) lower activation temperature; (2) less water required; (3) continuous processing (as opposed to batch for HCAS); and (4) reduced energy consumption. Yue et al. (Yue et al., 2020) demonstrated that >95 % depolymerisation of rectorite clay was obtained by heating at 170 °C for 1 h. These processes include a number of unit operations that add to the cost and energy requirements of running any operation that might incorporate them.

[0009] The process of the present invention has as one object thereof to overcome substantially the abovementioned problems of the prior art, or to at least provide a useful alternative thereto.

[00010] Throughout the specification, unless the context requires otherwise, the word “comprise” or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00011] Throughout the specification, unless the context requires otherwise, the word “contain” or variations such as “contains” or “containing”, will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

[00012] Each document, reference, patent application or patent cited in this text is expressly incorporated herein in their entirety by reference, which means that it should be read and considered by the reader as part of this text. That the document, reference, patent application, or patent cited in this text is not repeated in this text is merely for reasons of brevity. [00013] Reference to cited material or information contained in the text should not be understood as a concession that the material or information was part of the common general knowledge or was known in Australia or any other country.

Disclosure of the Invention

[00014] In accordance with the present invention there is provided a process for the treatment of a lithium slag, the process comprising the method steps of:

(i) Passing the lithium slag to an activation step in which the lithium slag is heated to an elevated temperature of less than about 250 °C in the presence of an alkali;

(ii) Passing the activated product of step (i) to a hydrothermal synthesis step in which the activated product is heated at an elevated temperature for a period of time, thereby producing a wet sludge containing crystalline, synthetic zeolite; and

(iii) Passing the wet sludge from step (ii) to a solid liquid separation step whereby a zeolite product is produced.

[00015] Preferably, the lithium slag comprises both aluminium and silica species. Still preferably, the lithium slag is a spodumene leachate residue. The lithium slag may preferably comprise a mix of lithium slag materials from different sources.

[00016] The temperature of the activation step is preferably:

(i) less than about 200 °C; or

(ii) about 150 °C.

[00017] Preferably, the alkali of the activation step is chosen from the group of NaOH, KOH and a mix of both NaOH and KOH. [00018] Still preferably, where NaOH is the alkali employed in the activation step the molarity is:

(i) greater than about 100 M;

(ii) greater than about 150 M;

(iii) between about 100 M and 500 M; or

(iv) about 479 M.

[00019] The molar ratio of NaOH/(Si + Al) in the activation step is preferably:

(i) greater than about 3; or

(ii) about 3.078.

[00020] Preferably, the synthetic zeolite produced in step (iii) is a zeolite X or a zeolite A.

[00021] In one form of the present invention the lithium slag is subjected to a size reduction step prior to the activation step (i). Preferably, the alkali is similarly subjected to a size reduction step prior to the activation step (i).

[00022] Preferably, little if any water is added during the activation step (i). Still preferably, the water/(Si + Al) Molar ratio in the activation step (i) is:

(i) less than about 0.4; or

(ii) about 0.358.

[00023] Preferably, the elevated temperature of the hydrothermal step (ii) is about 80°C. The hydrothermal step (ii) is preferably undertaken over a period of between 2 to 18 hours. Description of the Drawings

[00024] The present invention will now be described, by way of example only, with reference to one embodiment thereof and the accompanying drawing, in which:-

Figure 1 is a diagrammatic representation of a process for the synthesis of zeolites from spodumene leachate residue in accordance with the present invention;

Figure 2(a) is a graphical representation of the impact of activation temperature upon subsequent hydrothermal synthesis reaction to produce zeolite A; and

Figure 2(b) is a graphical representation of the impact of NaOFI molarity upon subsequent hydrothermal synthesis reaction to produce zeolite A.

Best Mode(s) for Carrying Out the Invention

[00025] The present invention provides a process for the treatment of a lithium slag, the process comprising the method steps of:

(i) Passing the lithium slag to an activation step in which the lithium slag is heated to an elevated temperature of less than about 250 °C in the presence of an alkali;

(ii) Passing the activated product of step (i) to a hydrothermal synthesis step in which the activated product is heated at an elevated temperature for a period of time, thereby producing a wet sludge containing crystalline, synthetic zeolite; and

(iii) Passing the wet sludge from step (ii) to a solid liquid separation step whereby a zeolite product is produced. [00026] The lithium slag comprises both aluminium and silica species and is, for example, a spodumene leachate residue. In one form of the invention the lithium slag comprises a mix of lithium slag materials from different sources.

[00027] The temperature of the activation step is:

(i) less than about 200 °C; or

(ii) about 150 °C.

[00028] The alkali of the activation step is chosen from the group of NaOH, KOH and a mix of both NaOH and KOH.

[00029] Where NaOH is the alkali employed in the activation step the molarity is:

(i) greater than about 100 M;

(ii) greater than about 150 M;

(iii) between about 100 M and 500 M; or

(iv) about 479 M.

[00030] The molar ratio of NaOH/(Si + Al) in the activation step is:

(i) greater than about 3; or

(ii) about 3.078.

[00031] The synthetic zeolite produced in step (iii) is a zeolite X or a zeolite A.

[00032] In one form of the present invention the lithium slag is subjected to a size reduction step prior to the activation step (i). For example, the particle size range for the lithium slag is less than 50 miti, particularly in the range of between about 0.71 and 48 pm.

[00033] The form of the alkali utilised may be such that it is in solid form, having a size in the range of about 0.6 to 0.9 mm ‘pearls’. The alkali may similarly be subjected to a size reduction step prior to the activation step (i).

[00034] Little if any water is added during the activation step (i). In one form the water/(Si + Al) Molar ratio in the activation step (i) is:

(i) less than about 0.4; or

(ii) about 0.358.

[00035] The elevated temperature of the hydrothermal step (ii) is about 80°C. The hydrothermal step (ii) is undertaken over a period of between about 2 to 18 hours.

[00036] The present invention provides a process for zeolite production, in one form providing a process for transforming lithium slag to zeolites, those zeolites being suitable for use in applications including, but not limited to, adsorption, ion exchange, catalysis and gas separation. The present invention provides a process for making synthetic zeolites such as but not limited to zeolite X (also known as zeolite 13X) and zeolite A (also known as zeolite LTA, zeolite NaA or zeolite 4A) from spodumene leachate residue.

[00037] The source and composition of lithium is not limited as invariably the waste material is largely comprised of aluminium and silica species. One embodiment of this invention uses a single lithium slag material, whilst a further embodiment of this invention employs a mixture of lithium slag materials from different industry sources. Those skilled in the art will understand that the composition of the lithium slag can be modified by further addition of silica sources such as silica gel, sodium silicate, sand, and diatomite if the silicon/aluminium ratio is required to be increased. Similarly, those skilled in the art will also understand that the composition of the lithium slag can be modified by further addition of aluminium sources such as AI(OH)3, aluminium metal, or sodium aluminate to decrease the silicon/aluminium ratio.

[00038] In Figure 1 there is shown a process 10 for zeolite production in accordance with one embodiment of the present invention. In the process 10 a powdered lithium slag 12 is activated 14 at relatively low temperatures (for example less than about 250 °C and more particularly less than about 200 °C, and further particularly at a temperature of about 150 °C) in the presence of a suitable alkali 16, for example sodium hydroxide. Notably potassium hydroxide or mixtures of sodium hydroxide and potassium hydroxide could be employed if the target zeolite was one in which potassium has typically been used in the synthesis processes of the prior art, for example zeolite F, zeolite N, zeolite L, zeolite O, or chabazite.

[00039] One aspect of the present invention is the preferred use of lithium slag and alkali hydroxide materials which are finely ground using ball milling or any other diminution technology as known in the state of the art. Without wishing to be bound by theory it is thought that increasing the degree of contact by greater homogenization of the lithium slag/alkali hydroxide mixture ultimately results in a higher quality synthetic zeolite product. Surprisingly, it was discovered in this invention that adding water to aid this mixing of lithium slag and alkali hydroxide was not conducive to formation of high-quality synthetic zeolites.

[00040] The process of the present invention has the advantages that there is no need to knead the lithium slag/alkali hydroxide mixture which had been described in previous disclosures (2016; Yue et al., 2020). Thus, the cost of an additional unit operation is avoided. In addition, there is no need to crush pellets produced after the kneading/calcination step; again resulting in savings due to avoidance of a unit operation.

[00041] The fact that minimal water is required in the activation step described in this invention also means that energy costs associated with evaporation of water during the activation stage are minimized. In addition, the limited amount of water present also means that it is possible to continuously activate the lithium slag/alkali hydroxide mixture by heating in a rotary kiln or similar equipment. Once the lithium slag is activated according to this invention then hydrothermal synthesis conditions as known in the art can be applied to convert the activated material into a range of synthetic zeolites.

[00042] The general procedure to activate the lithium slag involved initial crushing of the raw materials to reduce the particle size.

[00043] The lithium slag composition was characterized by use of a wavelength dispersive X-ray fluorescence (WD-XRF) major element analysis facility. Samples were prepared by weighing 1 .00 g of lithium slag into a 95/5 % Pt/Au crucible; followed by 10 g of vitreous 50:50 lithium tetraborate:lithium metaborate flux comprising 0.5 % lithium iodide (Claisse Scientific). Samples were fused for 20 minutes at 1050 °C with agitation. The glass discs were analysed using a PANalytical Axios WD-XRF equipped with a 1 kW Rh tube. The PANalytical Wide Ranging Oxide Calibration (WROXI) protocol was followed using associated standards. Loss on fusion (LOF) was estimated by mass difference after glass disc fusion. The lithium slag and alkali hydroxide are then mixed together, and minimal water 18 added according to the scope of this invention.

[00044] Pleating the aforementioned mixture at an appropriate temperature and time is the next stage 20 of the process 10. A rotating kiln is preferred on the basis that the mixture does not adhere to the sides of the heating device if this approach is used. If the aforementioned mixture is not heated then a hard deposit is formed on the heating device surfaces exposed to the reactant mixture which is difficult to remove. To estimate the effectiveness of the lithium slag activation the activated sample was added to a dilute hydrochloric acid solution in accordance with the method described by Yue et al. (Yue et al., 2020). Activation was described in terms of active alumina and active silica species. The value of active silica and alumina was determined by analysing the dissolved silicon and aluminium in the acid solution. Specifically, 0.05 g of activated material was accurately weighed and transferred into a beaker. Then 100 mL of 0.1 M hydrochloric acid was added. This mixture was then stirred at ambient temperature for 30 minutes upon which time the solids remaining were separated from the acidic solution. After the analysis, the fraction of active silica and alumina was calculated on the basis of the original amounts of alumina and silica in the activated material. If desired the activated product could be aged for an appropriate time at either ambient temperature or above ambient temperature but less than the zeolite crystallization temperature.

[00045] The activated lithium slag/alkali hydroxide material can then be placed in a suitable vessel for hydrothermal treatment or synthesis 22 along with water and any additional sodium aluminate (or similar aluminium containing material such as AI(OH)3, waste aluminium scrap and the like) or silica containing species such as sodium silicate, silica gel, diatomite etc. as is known in the art; required to adjust the silicon/aluminium molar ratio. Appropriate temperatures and reaction times were then used to convert the activated material into crystalline, synthetic zeolites based upon previous literature (Kostinko, 1982; Kostinko, 1984).

[00046] Once the hydrothermal synthesis 22 is completed then the sludge needs to be separated 24 into a solid fraction 26 and a liquid fraction 28 with equipment such as a centrifuge, belt press or similar. The resultant solid fraction 26 or “wet zeolite cake” is then washed 30 with water until a determined pH value is reached, producing solids 32 and wastewater 34. The solids 32 from the wash 30 are dried 36 using a spray drier or an oven to provide a zeolite product 38. The specific form of the drying apparatus is not particularly important so long as it dries the material cost effectively.

[00047] The liquid fraction 28 “mother liquor” comprises excess alkali (e.g. sodium hydroxide, potassium hydroxide, or lithium hydroxide) and also dissolved aluminium and/or silica species. All three identified components in the mother liquor are valuable and, in one form of the invention, will be recycled to the activation stage 14. Evaporation 40 of mother liquor is often required to recover the alkali, silicates, and aluminates in a usable form for the activation stage 14. Water collected from evaporation 40 is not wasted and can be used in the wash 30 of the zeolite cake 26 and/or supply the water 18 to the activation stage 14 and/or the fused/water mixture.

[00048] Identification of the zeolite product crystallinity and composition is routinely conducted using X-ray diffraction (XRD). Quantitative XRD can also be used by micronizing samples which contain an internal standard (usually corundum 10 wt%) and forming a pressed powder. TOPAS v5 software or similar can be employed to perform Rietveld analysis to determine the crystalline content.

[00049] The process of the present invention will now be described with reference to the following non-limiting examples.

Example 1

[00050] Spodumene leachate residue (SLR) was supplied from a lithium ore deposit in Western Australia. SLR comprised of relatively small, finely ground particles, with a particle size range between 0.71 and 48 [pm] having a d50 = 11.9 [pm] A typical analysis is illustrated in Table 1 below.

Table 1 : X-ray fluorescence analysis of spodumene leachate residue [00051] Quantitative X-ray diffraction (XRD) revealed the presence of SLR, quartz, lithium sulphate and non-diffracting material, as shown in Table 2 below.

Table 2: Quantitative XRD analysis of SLR

[00052] Table 3 indicates the experimental details employed for activation of the spodumene leachate residue; wherein the alkali used was sodium hydroxide.

[Remainder of Page Left Blank Intentionally]

Table 3: Activation conditions for SLR

[Remainder of Page Left Blank Intentionally] [00053] The ratios of the materials used to activate spodumene leachate residue were:

NaOH/(Si+AI) molar ratio = 3.078 Water/(Si+AI) molar ratio = 0.358

[00054] The water/(Si+AI) ratio used in this example was less than the lower limit disclosed by WO 2016/078035 A1 (2016) [Table 4 below] and thus was not expected from prior disclosures to activate the spodumene leachate residue. Hydrothermal reaction at 80 °C for 2 to 18 hours was completed for all the activated materials illustrated in Table 5 below.

Table 4: Summary of Sub Molten Salt Conditions for Synthesis of Zeolites from Spodumene Leachate Residue based on WO 2016/078035 A1 (2016)

NaOH/(Si+AI) molar ratio = 3.5 Water/(Si+AI) molar ratio = 1.5

NaOH/(Si+AI) molar ratio = 3 Water/(Si+AI) molar ratio = 1

NaOH/(Si+AI) molar ratio = 2.5 Water/(Si+AI) molar ratio = 0.5 NaOH/(Si+AI) molar ratio = 2

NaOH/(Si+AI) molar ratio = 1.5

NaOH/(Si+AI) molar ratio =

1

Table 5: Reaction conditions used to prepare zeolites from activated SLR [00055] Analysis of the zeolite product from hydrothermal reaction of activated SLR revealed that faujasite (zeolite X) material was formed with H20/Na20 ratio ranging from 35 to 50 [Table 6 below]. Notably, no cancrinite or sodalite by-products were detected. A reaction time of 4 hours was sufficient in this example to form the target faujasite zeolite. This example has surprisingly shown in light of the prior art that faujasite zeolite was indeed made by activating SLR using high alkalinity activation conditions.

Table 6: Quantitative X-ray diffraction analysis of zeolite products made using hydrothermal synthesis of activated SLR Example 2 (Comparative)

[00056] To illustrate the importance of NaOH molarity in the SLR activation stage, the NaOH molarity was reduced from 479 M [Example 1] to 264 M (while keeping all other experimental conditions the same) [Table 7]

Table 7: Activation conditions for SLR; NaOH molarity = 264 M

[00057] As in Example 1 , the fused material was added to water (H20/Na20 ratio ranging from 35 to 50) and subsequently reacted at a temperature of 80 °C for 2 to 18 hours [Table 8 below]. Table 8: Synthesis conditions for making zeolite X from spodumene leachate residue: Na20/SiC>2 ratio = 1.22 in activated material

[00058] Analysis of the zeolite product from hydrothermal reaction of activated SLR revealed that faujasite (zeolite X) material was not formed to a significant extent compared to Example 1 (regardless of H20/Na20 ratio) [Table 9]. Notably, both cancrinite and sodalite by-products were detected in substantial quantities. Reaction times of 2 to 18 hours were sufficient in this example to relatively rapidly form the cancrinite and sodalite. Table 9: Quantitative X-ray diffraction analysis of zeolite products made using hydrothermal synthesis of activated SLR; Activation conditions for NaOH molarity = 264 M

Example 3 (Comparative)

[00059] In a similar manner to Example 1 , activation of SLR was conducted by heating a mixture of SLR, NaOH and water at a prescribed temperature for 2 hours. Subsequently water was added to the fused material and hydrothermal synthesis conducted at 80 °C for 1 hour. Figure 2 (a) shows that the formation of zeolite A was dependent upon the NaOH molarity employed in the activation stage. A sodium hydroxide molarity of a minimum value of 150 M enhanced the zeolite A quality. In particular, if a sodium hydroxide molarity of 150 or greater was not employed then the unwanted by-product sodalite was made, as can be seen in Figure 2(b).

[00060] Notably, the activation conditions described in WO 2016/078035 A1 taught that high quality zeolites could be formed under different conditions. Example 1 disclosed that NaOH molarity = 83.3, temperature = 260 °C and activation time = 4 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of unwanted by-products, such as cancrinite. Example 3 discloses that NaOH molarity = 77.2, temperature = 200 °C and activation time = 4 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of by products, such as cancrinite. Example 4 disclosed that NaOH molarity = 108.2, temperature = 250 °C and activation time = 3 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of by-products such as cancrinite. Example 5 disclosed that NaOH molarity = 101.9, temperature = 250 °C and activation time = 3 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of by-products such as cancrinite. Example 6 disclosed that NaOH molarity = 74.1 , temperature = 250 °C and activation time = 2.5 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of by-products such as cancrinite. Example 7 disclosed that NaOH molarity = 184, temperature = 100 °C and activation time = 0.5 h was suitable. According to this invention the prior art was not suitable when activating spodumene leachate residue and would result in the formation of by-products such as cancrinite.

[00061] As can be seen with reference to the above description, the process for zeolite production of the present invention avoids at least a number of the problems associated with the prior art.

[00062] It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range from about 1 micrometer (pm) to 2 pm should be interpreted to include not only the explicitly recited limits of from between from about 1 pm to 2 pm, but also to include individual values, such as about 1.2 pm, about 1.5 pm, about 1.8 pm, etc., and sub-ranges, such as from about 1.1 pm to about 1.9 pm, from about 1.25 pm to about 1.75 pm, etc. Furthermore, when “about” and/or “substantially” are/is utilised to describe a value, they are meant to encompass minor variations (up to +/- 10%) from the stated value.

[00063] Modifications and variations such as would be apparent to the skilled addressee are considered to fall within the scope of the present invention.

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