| Turquoise is a hydrous Copper-aluminum phosphate, with the chemical formula CuAl6 [PO4]4(OH)8·4H2O, which is triclinic, and most named after their pineal shape and the blue-greencolors. It's a very popular traditional ancient and modern precious jade.In recent years, the new turquoise deposit and exploitation is far below the social demand,resulting in the imbalance between supply and demand of the high-quality turquoise orebecoming more and more serious in the jewelry market both at home and abroad, which has ledto a sharp rise of the turquoise's price for five years. Constrained by the complex depositgeological conditions, the original quality of most turquoise is quite poor, bad color, light-coloredor colorless, cracks and porosity are ubiquitous, so it is too difficult to achieve high quality andlose their due value. Because of the behindhand mining technology and processing equipment ofturquoise mine, and the low resource utilization rate of resources, together with the disorderlycompetition of turquoise processing industry, most turquoise substantial resources were wastedand several tons of small slag and residual slag powder of turquoise were left abandoned. Sosynthetic recycling for the turquoise resources should be strengthened. Meanwhile, the traditionalplastic injection treated turquoise are filled with many organic polymers, resulting in thecomposition, structure and physical characteristics of turquoise are quite different from naturalturquoise. Moreover, this method is limited to larger turquoise material, but difficult to specifythe implementation of the small particles turquoise material. Therefore, it is very important toresearch the recycling of wasted turquoise, improving the quality grade of turquoise, andalleviating the short supply of turquoise.The small particles of waste turquoise materials and sub-monomer turquoise materials havebeen chose for the study. Selecting Al (H2PO4)3 with chemical composition is similar to turquoiseand related supplementary materials, using different chemical formulas and under differentconditions, the small particles of waste turquoise materials and sub-monomer turquoise materialsare improved to a larger monomer scale and a higher quality jewelry grade respectively by theway of pressing reconstruction and soaking filling. It will provide a scientific basis for recycling of turquoise resources in our country. The main conclusions are as follows:1. The research is focus on the turquoise deposit in Qingu, Labashan in Zhushan county andYun county of Hubei province as well as Maanshan, Anhui Province. The geologicalcharacteristics, chemical composition, microstructure and colorific mechanism of naturalturquoise have been studied. The result shows that: (1) the color of turquoise is controlled by Fe3+,Cu2+, and surface weathering intensity. (2) The structure of turquoise can be described asmicrocrystal-squama texture and spherulitic texture. There are often impurities contained by iron,carbon, a small amount of sericite and small clay mineral in turquoise. (3) The microstructure ofturquoise microcrystal can be described as scale-like, columnar, and sheet-like shape. (4) Thespectra of the turquoise from different localities are basically similar and subtly different. The3505～3070 cm-1 spectra assigned to theν(OH) stretching vibrations and the bands observed at1198-1010 cm-1 assigned toν3 (PO4) antisymmetric stretching vibrations. The spectra peaks at839 cm-1～781cm-1 and 652 cm-1～483cm-1 are attributed to theδ(OH) bending vibrations andν4(PO4) bending vibrations, respectively. (5) In the visible wavelength range, two characteristicabsorption bands of turquoise a1 and a2 can be observed, which are caused by Fe3+ d-d electrontransitions with 423～438nm and Cu2+d-d electron transitions with 683～688nm, respectively. (6)The combination and content of H2O constraint the color of turquoise at a certain extent.2. The basic method of processing loose turquoise is: Al(H2PO4)3 solution as main adhesivereagents, MgO as accessorial material, and "soaking-heating-insulation-cooling-processing"as the basic experimental process at constant pressure. The result shows that, thequality of Al(H2PO4)3, soaking time, soaking temperature, soaking way, holding temperature,holding time, heating rate and the solution of additives have different effects on processingeffects. (1) By studying the effect at individual process parameters under different conditions, abest process conditions is selected, that is, the selection of Al(H2PO4)3 mass fraction of about50%, PH value of control at 1.5～2, and 5～7g MgO per 100ml adhesive. The soaking of loosenturquoise under low temperature is appropriated. According to the changes of quality and scale ofturquoise, the soaking time is generally ranging from a few days to ten days. Filled turquoises arerequired heat-curing treatment after the gel at low temperature. The turquoise with insufficienttreatment can be carried out in accordance with the above process of filling, taking two or moretimes soaking treatment. Only the processing conditions are strictly controlled, the results wouldbe optimal. (2) After the treatment, the color of loose turquoise can be enhanced to a high degreeof saturation of blue-green, green-blue and green, transparency improved; gloss strengthened,and has good durability. The hardness can increased to resist scored by forceps, withmicro-hardness between 106～297N/mm2.The structure is denser and has good processingperformance. Cutting and grinding processing is consistent with natural turquoise. The looseturquoise after treatment can be processed into jewelry with turquoise beads, ring stones, andpendants et al.3. The small particles of wasted turquoise are pressed reconstruction with the same adhesivesolution of the filling treatment experiment. (1) Sorting purification of the turquoise scrapsmaterials and gravity concentration and flotation united sorting method are selected to screen out the carbonaceous impurities from turquoise, and selecting HCl, hyposulfite and oxalate to mixthe turquoise for general reaction to clean out the Fe3+ impurities from turquoise. (2) In theprocess of wasted turquoise reconstruction experiment, proportion of adhesive, size of turquoisepowder, and time of compression stress, insulation temperature and holding time show differenteffects on results. The optimal process conditions are: adhesive ratio between 23%-25%, powderparticle size is no less than 250 eyelet, compression stress is between 1.5*104MPa/m2 and3.0*104MPa/m2, pressure time not less than 10 min, heat solidify suppressed body afterself-hardening at room temperature for 1～2 days in accordance with a certain temperature curve.(3) After the treatment, the color of turquoise is uniform with single color-light blue green, andmicro-hardness is between 105N/mm2 and 198N/mm2. The gemology characteristics ofturquoises after treatment, such as gloss, refractive index, UV fluorescence and so on, are similarwith the natural ones. With excellent processing properties, the turquoises after treatment can beprocessed into jewelry with turquoise beads and ring stones.4. The study of microstructure and chemical composition analysis of the turquoises before andafter treatment indicate that: (1) the dense degree, color and hardness of turquoise after treatmentare controlled by aluminum phosphate adhesive fller's content. The turquoise filled morecompletely and with higher levels of adhesives, the structure is denser and the color is darker. (2)The micro-pores of the turquoise after treatment are completely filled as gelatinous. Moreover,the turquoise crystallites are dissolved relatively smooth and some have been dissolved withweak recrystallization reaction. (3) The EDX test and chemical composition analysis show thatthe turquoise with filled adhesive has higher content of P2O5. MgO content has increased to0.08%～0.31%, but other chemical compositions have no notable changes, so on with thecoloring elements Cu and Fe. (4) The color of treated turquoise is related to the former Cu and Fecontent, a high ratio of Cu/Fe conduce blue, but high Fe content conduce green.5. The study of IR spectra and XRD of the turquoises before and after treatment show that: (1)the mineral composition and molecular structure of turquoise have no noticeable change, buthave a certain degree of amorphous. The amorphous structure is relevant with the filling ofaluminum phosphate that is the inorganic polymer network structure formed when the aluminumphosphate adhesive dehydrated. (2) In the pressing reconstruction experiment, the addition ofaluminum phosphate adhesive promoted microcrystal turquoise net plane (120) growth, but wasnot apparent in filled turquoise.6. The DTA study shows that the endothermic and exothermic reaction temperatures of theturquoise after treatment have a certain degree of fall than the natural ones caused by the additionof aluminum phosphate.7. The improving principle and reaction mechanism for recycling of turquoise are summarized.According to the micro-Brownian motion, aluminum phosphate solution gradually infiltrated tothe interior of turquoise along the micro-pores or the borders of turquoise particles. Thealuminum phosphate within turquoise polymerized when heating and made some turquoisecrystallites dissolved and recrystallizated. Then the reaction products filled the originalmicro-pores, and cemented the original loose mineral particulates by the combination of micro-macro integration and chemical bond. On the one hand, the porosity is lower, the diffusereflectance of light is reduced and the transparency and color of turquoise are improved. On theother hand, the mineral particulates connect more closely to make the hardness and the processperformance improved.
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