WO2018040703A1 - 一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法 - Google Patents

一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法 Download PDF

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WO2018040703A1
WO2018040703A1 PCT/CN2017/090656 CN2017090656W WO2018040703A1 WO 2018040703 A1 WO2018040703 A1 WO 2018040703A1 CN 2017090656 W CN2017090656 W CN 2017090656W WO 2018040703 A1 WO2018040703 A1 WO 2018040703A1
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magnesium
magnesium hydroxide
filtrate
heavy metal
metal sludge
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PCT/CN2017/090656
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English (en)
French (fr)
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许开华
盛广宏
张云河
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荆门市格林美新材料有限公司
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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01F—COMPOUNDS OF THE METALS BERYLLIUM, MAGNESIUM, ALUMINIUM, CALCIUM, STRONTIUM, BARIUM, RADIUM, THORIUM, OR OF THE RARE-EARTH METALS
    • C01F5/00—Compounds of magnesium
    • C01F5/14—Magnesium hydroxide
    • C01F5/22—Magnesium hydroxide from magnesium compounds with alkali hydroxides or alkaline- earth oxides or hydroxides
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B26/00—Obtaining alkali, alkaline earth metals or magnesium
    • C22B26/20—Obtaining alkaline earth metals or magnesium
    • C22B26/22—Obtaining magnesium
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/01—Particle morphology depicted by an image
    • C01P2004/03—Particle morphology depicted by an image obtained by SEM
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

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  • the invention belongs to the technical field of resource recycling and hydrometallurgy, and more particularly to a method for recovering high-purity flame-retardant magnesium hydroxide from heavy metal sludge.
  • magnesium hydroxide There are five main methods for industrial production of magnesium hydroxide: (1) production of magnesium hydroxide by reaction of limestone and brine; (2) reaction of magnesium hydroxide with brine and brine, and magnesium hydroxide; (3) calcination Magnesite, dolomite and brine, halogen block reaction to produce magnesium hydroxide; (4) using MgO hydration to form magnesium hydroxide, where MgO must be lightly burned to ensure hydration activity; (5) with ammonia and brine, The halogen block reacts to produce magnesium hydroxide.
  • the surface modifier is used to modify the magnesium hydroxide, and the magnesium hydroxide flame retardant product conforming to the flame retardant property is obtained by a conventional method such as a seed crystal method or a hydrothermal method.
  • the raw materials for industrial production of magnesium hydroxide are widely used, but the brine is easy to corrode the equipment and therefore requires high equipment.
  • the calcination process of magnesite and dolomite has high energy consumption, so the conventional method for preparing magnesium hydroxide industrially produces magnesium hydroxide.
  • the surface modifier is used to modify the magnesium hydroxide, and the magnesium hydroxide flame retardant product conforming to the flame retardant property is obtained by a conventional method such as a seed crystal method or a hydrothermal method.
  • a conventional method such as a seed crystal method or a hydrothermal method.
  • the raw materials for industrial production of magnesium hydroxide are widely used, but the brine is easy to corrode the equipment, so the equipment is required to be high.
  • the calcination process of magnesite and dolomite has high energy consumption. Therefore, the conventional method for preparing magnesium hydroxide flame retardant has high equipment requirements. The disadvantage of high energy consumption.
  • the laterite nickel ore used in the extraction of cobalt-nickel industry contains about 20% of magnesium in mass fraction, and produces 1t of metallic cobalt-nickel, which is associated with about 55t of sludge.
  • Magnesium enrichment is not rationally utilized in sludge.
  • the sludge is rich in valuable metals such as cobalt, nickel, manganese and magnesium. At this stage, it is used for acid leaching. Recycling of precious metals such as cobalt, nickel and manganese (as raw material liquid for ternary battery materials), and a large amount of magnesium resources produced during acid leaching.
  • the set circulates in the system, and magnesium does not have a suitable open circuit (made into a product or efflux) and thus is difficult to handle. Due to the lack of suitable treatment methods for magnesium resources, serious environmental burdens and waste of resources have been caused.
  • the object of the present invention is to provide a method for recovering magnesium from heavy metal sludge and a method for recovering high-purity flame-retardant magnesium hydroxide from heavy metal sludge, by which cobalt cobalt is extracted.
  • the heavy metal sludge extracted in the industry (hereinafter referred to as heavy metal sludge) is processed, which not only shortens the heavy gold It recovers magnesium from sludge, improves the utilization rate of magnesium, and ensures the recovery rate and high purity of subsequent treatment of valuable precious metals such as cobalt and nickel in heavy metal sludge, improves industrial added value, and the process is simple and easy, and can be large-scale Industrialization.
  • the invention provides a method for recovering magnesium from heavy metal sludge, comprising the following steps:
  • Step 1 pre-treatment water washing: the heavy metal sludge is added to the pure water according to the mass ratio of pure water to sludge dry matter of 8:1 to 15:1, stirred while heating, heated to 80-85 ° C and kept warm, in the process of heating and stirring. Adding 0.4g/L to 0.6g/L of dilute sulfuric acid until the pH is 7.0-8.0 at 80-85 ° C, stirring is continued for 10-15 min, and the water-slag mixture is dehydrated by plate and frame filtration to obtain filtrate 1 and filter residue. 1; The filter residue 1 is dehydrated by hot water washing and filtering for 1 to 3 times to obtain a filtrate 2; the filtrate obtained by combining the filtrate 1 and the filtrate 2 is a magnesium liquid;
  • Step 3 removing silicon from the magnesium solution: adjusting the pH of the raffinate 1 with a 2 to 5 mol/L aqueous solution of sodium hydroxide to 5.0 to 6.0 to obtain a raffinate 2, and adding polyaluminum chloride to the raffinate 2 and Polyacrylamide is added in a ratio of 5 to 15 mg of polyaluminum chloride and 0.1 to 0.5 mg of polyacrylamide per liter of raffinate 2, stirred for 50 to 80 minutes, and filtered and vacuum filtered to obtain a filtrate and a residue. Magnesium solution; the filter residue is washed with hot water 3-4 times and discharged.
  • Step 4 adding alkali to magnesium precipitation: taking a certain volume of the refined magnesium liquid obtained in step 3, measuring the magnesium ion concentration in the magnesium solution, adding 4 ⁇ 5mol / L NaOH aqueous solution to adjust the pH value to 11.5 ⁇ 12.0, at a temperature of 50 ⁇ 70 ° C fully reacted 30-40min magnesium, that is, magnesium ions combined with hydroxide ions to form magnesium hydroxide precipitate, to obtain milky white turbid liquid;
  • Step 5 surface modification: according to the volume of the magnesium liquid in the step 4 and the magnesium ion concentration in the magnesium solution, calculate the mass of the magnesium hydroxide in the step 4 in the complete sedimentation of the magnesium ions, and add the surface modification to the milky white turbid liquid obtained in the step 4 Stearic acid, the amount of stearic acid added accounts for 2 to 6% of the calculated mass of magnesium hydroxide, at 60-80 ° C, the modification of magnesium hydroxide 70 ⁇ 100min;
  • Step 6 aging: the product obtained in step 5 is aged at 65-80 ° C for 2-6 h, and the stirring speed is lowered to 100-150 r/min during the aging process;
  • Step 7 hydrothermal treatment: the product obtained in step 6 is dehydrated until the mass of magnesium hydroxide in the product accounts for 30-40% of the mass of the product obtained in step 6, and the temperature is adjusted to 150-180 ° C in the autoclave, and the hydrothermal treatment is 3-8 h. Obtain a slag sample;
  • Step 8 The slag sample obtained in the step 7 is dehydrated by vacuum pumping, alternately washed with hot water and alcohol, and dried at 100-105 ° C to obtain a high-purity flame-retardant magnesium hydroxide product.
  • the temperature of the hot water used for washing is 80-90 °C.
  • the heavy metal sludge is added to the pure water according to the liquid-solid mass ratio of 15:1; heated to 85 ° C and kept warm; 0.6g / L of dilute sulfuric acid is added until the pH is measured at 85 ° C is 8.0; stirring is continued for 15 min; Wash and filter for 3 times.
  • the diisooctyl phosphate extractant is prepared by diluting to a volume ratio of 20 to 30% with sulfonated kerosene, and saponifying with 20 to 30% of Wt aqueous solution of NaOH to a saponification ratio of 30 to 40%.
  • the magnesium ion concentration in the magnesium liquid is measured by a Shimadzu atomic absorption spectrophotometer AA-7000.
  • dehydration can be performed by plate frame pressure filtration or vacuum pump suction filtration.
  • the heavy metal sludge passes through the pretreatment washing process, in which most of the magnesium is washed out and then enters the magnesium liquid.
  • the magnesium in the magnesium liquid accounts for more than 99% of the magnesium in the heavy metal sludge; meanwhile, the content of Ni in the filtrate is less than 0.6. Mg/L, Co, Mn, Zn were not detected, and the content of Cu was less than 0.2 mg/L, thereby ensuring high recovery of precious metal cobalt nickel in the recovered filter residue.
  • Figure 1 is a process path diagram of the present invention.
  • a method for recovering high-purity flame-retardant magnesium hydroxide from heavy metal sludge comprising the following steps:
  • Magnesium accounts for more than 99% of magnesium in heavy metal sludge, and the content of Ni is 0.5mg/L. Co, Mn and Zn are not detected.
  • the content of Cu is 0.1mg/L, Na, Ca, Cl - Although it is high in content, it is not harmful to the preparation of magnesium hydroxide.
  • the pH was adjusted to 2 with 1 mol/L hydrochloric acid, and extracted with diisooctyl phosphate extractant.
  • O/A volume ratio of organic phase to aqueous phase
  • 2-stage countercurrent extraction was carried out, and the extraction temperature was obtained.
  • raffinate 1 was obtained.
  • the diisooctyl phosphate extractant is prepared by diluting to a volume ratio of 20% with sulfonated kerosene and saponifying with a 20% Wt aqueous solution of NaOH until the saponification rate reaches 30%.
  • the raffinate 1 is adjusted to a pH of 5.0 with a 2 mol/L sodium hydroxide aqueous solution to obtain a raffinate 2; and a polyaluminum chloride and a polyacrylamide are added to the raffinate 2, Adding 5-15 mg of polyaluminum chloride and 0.1-0.5 mg of polyacrylamide per liter of raffinate 2; controlling the temperature at 50 ° C, stirring for 50 min, filtering with a vacuum pump to obtain a filtrate and a small amount of filter residue, the filtrate In order to refine the magnesium liquid; the filter residue is washed with hot water 3-4 times and discharged.
  • step 5 The product obtained in step 5 was aged at 65 ° C for 2 h, and the stirring speed was lowered to 100-150 r/min during the aging process.
  • the slag sample obtained in the step 7 is dehydrated by vacuum pumping, alternately washed with hot water and alcohol, and dried at 100 ° C to obtain a high-purity flame-retardant magnesium hydroxide product.
  • the flame retardant magnesium hydroxide needs to meet three points (refer to the standard HGT 4531-2013 magnesium hydroxide for flame retardant): product purity ⁇ 93.0%, specific surface area (BET) ⁇ 20.0m 2 / g, 101 surface micro internal strain ⁇ ⁇ 3.0x10 -3 ;
  • product magnesium hydroxide particles are required to have a regular morphology, which is easy to disperse when added as a flame retardant.
  • the recovery rate of magnesium (product magnesium accounts for magnesium in heavy metal sludge) can reach 85.2%, product purity can reach 99.5% (measured by American Liman ICP-OES inductively coupled plasma emission spectrometer), particle size Distribution between 0.9-10.7 ⁇ m, average particle size D50: 7.02 ⁇ m (measured by Malvern 2000 laser particle size analyzer), specific surface area (BET) results of 15.7m 2 /g (US NOVA automatic nitrogen adsorption specific surface test SEM results showed that the particles were hexagonal (measured by FEI scanning electron microscopy), 101 microscopic internal strain ⁇ : 2.8 ⁇ 10 -3 (automatic X-ray diffractometer D/max-IIIA) The measurement equipment will not be described below.
  • a method for recovering high-purity flame-retardant magnesium hydroxide from heavy metal sludge comprising the following steps:
  • Magnesium accounts for more than 99% of magnesium in heavy metal sludge, and the content of Ni is 0.6mg/L. Co, Mn and Zn are not detected. The content of Cu is 0.2mg/L. The content of Na, Ca and Cl ⁇ is Higher but not harmful to the preparation of magnesium hydroxide.
  • the slag sample obtained in the step 7 is dehydrated by vacuum pumping, alternately washed with hot water and alcohol, and dried at 105 ° C to obtain a high-purity flame-retardant magnesium hydroxide product.
  • the recovery rate of magnesium (product magnesium accounts for the proportion of magnesium in heavy metal sludge) can reach 85.7%, the product purity can reach 99.8%, the particle size distribution is between 1.0-11.5 ⁇ m, the average particle size is 8.15 ⁇ m, BET The result was 14.9 m 2 /g, and the SEM results showed that the particles were hexagonal flakes, and the 101-microscopic internal strain ⁇ : 2.5 x 10 -3 .
  • a method for recovering high-purity flame-retardant magnesium hydroxide from heavy metal sludge comprising the following steps:
  • Magnesium accounts for more than 99% of magnesium in heavy metal sludge, and the content of Ni is 0.3mg/L. Co, Mn and Zn are not detected. The content of Cu is 0.1mg/L. The content of Na, Ca and Cl ⁇ is Higher but not harmful to the preparation of magnesium hydroxide.
  • Removal of silicon from magnesium solution adjust the pH of the raffinate 1 with a 3 mol/L sodium hydroxide aqueous solution to 5.5 to obtain a raffinate 2; add polyaluminum chloride and polyacrylamide to the raffinate 2, according to Adding 10 mg of polyaluminum chloride and 0.2 mg of polyacrylamide per liter of raffinate 2; controlling the temperature at 60 ° C, stirring for 60 min, filtering with a vacuum pump to obtain a filtrate and a small amount of filter residue, the filtrate being a refined magnesium liquid; The filter residue is washed with hot water 3-4 times and discharged.
  • the slag sample obtained in the step 7 is dehydrated by vacuum pumping, alternately washed with hot water and alcohol, and dried at 102 ° C to obtain a high-purity flame-retardant magnesium hydroxide product.
  • the recovery rate of magnesium (product magnesium accounts for magnesium in heavy metal sludge) can reach 85.5%, product purity can reach 99.6%, particle size distribution is between 1.1-11.7 ⁇ m, average particle size is 7.75 ⁇ m, BET The result was 14.4 m 2 /g, and the SEM results showed that the particles were hexagonal flakes, and the microscopic internal strain ⁇ of the 101 faces was 2.6 x 10 -3 .

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Abstract

提供一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，包括以下步骤：预处理水洗，将重金属污泥按照纯水与污泥干物质质量比8：1～15：1加入纯水，加热至80～85℃并用搅拌机搅拌，再加入0.4g/L～0.6g/L的稀硫酸调节pH至7.0～8.0，所得水渣混合物经板框压滤脱水，得滤液1和滤渣1，将滤渣1用热水洗涤过滤脱水1～3次，得滤液2，滤液1与滤液2合并所得滤液即为镁液；镁液依次进行除钙，除硅，加碱液沉镁，表面改性，陈化，水热处理，脱水、洗涤、烘干等步骤后制得高纯阻燃型氢氧化镁。本方法在保证金属钴镍回收率的同时，进一步提高了阻燃型氢氧化镁产品的纯度。

Description

一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法 技术领域
本发明属于资源循环利用和湿法冶金技术领域，更具体地说涉及一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法。
背景技术
工业上生产氢氧化镁主要有以下五种方法：(1)用石灰石和卤水反应生产氢氧化镁；(2)用氢氧化钠和卤水、卤块反应制氢氧化镁；(3)利用煅烧过的菱镁矿、白云石和卤水、卤块反应生产氢氧化镁；(4)利用MgO水合生成氢氧化镁，这里的MgO必须是轻烧产品以保证水合的活性；(5)用氨水和卤水、卤块反应制氢氧化镁。后期采用表面改性剂对氢氧化镁改性，使用晶种法，水热法等传统方法制得符合阻燃性能的氢氧化镁阻燃剂产品。工业上生产氢氧化镁的原料来源广泛，但卤水容易腐蚀设备因而对设备要求较高，菱镁矿及白云石的煅烧过程能耗高，因此常规方法制备氢氧化镁工业上生产氢氧化镁主要有以下五种方法：(1)用石灰石和卤水反应生产氢氧化镁；(2)用氢氧化钠和卤水、卤块反应制氢氧化镁；(3)利用煅烧过的菱镁矿、白云石和卤水、卤块反应生产氢氧化镁；(4)利用MgO水合生成氢氧化镁，这里的MgO必须是轻烧产品以保证水合的活性；(5)用氨水和卤水、卤块反应制氢氧化镁。后期采用表面改性剂对氢氧化镁改性，使用晶种法，水热法等传统方法制得符合阻燃性能的氢氧化镁阻燃剂产品。工业上生产氢氧化镁的原料来源广泛，但卤水容易腐蚀设备因而对设备要求较高，菱镁矿及白云石的煅烧过程能耗高，因此常规方法制备氢氧化镁阻燃剂存在设备要求高，能耗高的缺点。
萃取钴镍工业中使用的红土镍矿含有质量分数20％左右的镁，生产1t金属钴镍，伴生约55t的污泥，镁富集在污泥中没有得到合理利用。污泥中富含钴镍锰镁等有价金属，现阶段用以酸浸，回收利用钴镍锰等贵金属(作为三元电池材料制备的原料液)，酸浸过程中产生的大量镁资源富集在体系中循环，镁没有合适的开路(制成产品或者外排)因此处理困难。由于缺乏合适的对镁资源的处理方法，造成了严重的环境负担跟资源浪费。
综上，目前对萃取后的重金属污泥在处理过程中，存在浸出液中大量的镁难以分离，作为三元电池原料钴镍锰等纯度低，浸出液中大量镁资源无法合理利用导致镁资源浪费的问题。阻燃剂存在设备要求高，能耗高的缺点。
发明内容
为了解决上述技术问题，本发明的目的在于提出一种从重金属污泥中回收镁的方法以及一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，通过这种方法对萃取钴镍工业中萃取后的重金属污泥(下面简称重金属污泥)进行处理，不仅能够缩短从重金 属污泥中回收镁，提高镁的利用率，同时保证重金属污泥中钴镍等有价贵金属后续处理的回收率和较高的纯度，提高产业附加值，而且工艺简单易行，能够大规模产业化。
本发明提出一种从重金属污泥中回收镁的方法，包括以下步骤：
步骤1，预处理水洗：将重金属污泥按照纯水与污泥干物质质量比8：1～15：1加入纯水，边加热边搅拌，加热至80～85℃并保温，在加热搅拌过程中加入0.4g/L～0.6g/L的稀硫酸直至在80～85℃测得pH为7.0～8.0，继续搅拌10～15min，得水渣混合物经板框压滤脱水，得滤液1和滤渣1；将滤渣1用热水洗涤过滤脱水1～3次，得滤液2；滤液1与滤液2合并所得滤液即为镁液；
步骤2，镁液除钙：用1～5mol/L盐酸调节pH至2～3，加入磷酸二异辛酯萃取剂萃取，萃取时相比O/A(有机相与水相的体积比)＝1/1～1/2，进行2～4级逆流萃取，萃取温度为20～30℃，得到萃余液1；
步骤3，镁液除硅：将萃余液1用2～5mol/L的氢氧化钠水溶液调节pH值至5.0～6.0，得到萃余液2，向萃余液2中加聚合氯化铝和聚丙烯酰胺，按照每升萃余液2中加入5～15mg聚合氯化铝和0.1～0.5mg聚丙烯酰胺的比例加入，搅拌50～80min，用真空泵抽滤得滤液和滤渣，此滤液为精制镁液；滤渣用热水洗涤3-4次后排放。
步骤4，加碱液沉镁：取一定体积的步骤3中所得精制镁液，测量镁液中镁离子浓度，加入4～5mol/L的NaOH水溶液调节pH值至11.5～12.0，在温度50～70℃充分反应30-40min沉镁，即镁离子与氢氧根离子结合形成氢氧化镁沉淀，得到乳白色浊液；
步骤5，表面改性：根据步骤4中镁液体积及镁液中镁离子浓度，计算步骤4中镁离子完全沉降时的氢氧化镁质量，向步骤4所得产物乳白色浊液中加入表面改性剂硬脂酸，所加硬脂酸质量占所计算的氢氧化镁质量的2～6％，在60～80℃条件下，对氢氧化镁改性70～100min；
步骤6，陈化：将步骤5所得产物在65～80℃下陈化2～6h，陈化过程中调低搅拌速度至100～150r/min；
步骤7，水热处理：将步骤6所得产物脱水，直至产物中氢氧化镁质量占步骤6所得产物质量的30～40％，在高压釜中调整温度至150～180℃，水热处理3～8h，得到渣样；
步骤8，将步骤7所得渣样用真空泵抽滤脱水、使用热水与酒精交替洗涤、在100-105℃下烘干后制得高纯阻燃型氢氧化镁产品。
上述步骤1中，洗涤采用的热水的温度为80-90℃。
上述步骤1中，将重金属污泥按照液固质量比15：1加入纯水；加热至85℃并保温；加0.6g/L的稀硫酸直至在85℃测得pH为8.0；继续搅拌15min；洗涤过滤脱水3次。
上述步骤2中，磷酸二异辛酯萃取剂的制备方法为：用磺化煤油稀释至体积比20～30％，并用20～30％Wt的NaOH水溶液皂化，至皂化率达到30～40％。
上述步骤2中，萃取相用pH＝3.5～4.5的稀盐酸洗涤2次，再用0.5-2.0mol/L盐酸水溶液进行1级反萃，反萃时的相比O/A＝2/1～1/1，反萃温度为20～30℃，主要目的使 萃取剂得以重复利用。
上述步骤4中，所述镁液中镁离子浓度由日本岛津原子吸收分光光度计AA-7000测得。
上述步骤7中，可采用板框压滤或真空泵抽滤脱水。
本发明的有益效果：
1)重金属污泥通过预处理水洗过程，其中绝大多数镁洗出后进入镁液，镁液中镁占重金属污泥中镁的比例达到99％以上；同时，滤液中Ni的含量低于0.6mg/L，Co、Mn、Zn未检出，Cu的含量低于0.2mg/L，从而保证了回收的滤渣中贵金属钴镍的高回收率。
2)制备得到的氢氧化镁阻燃剂粗产品：产品中镁的一次回收率(产物镁占重金属污泥中镁的比例)达到84.8％以上，最高可达85.7％；产品纯度≥99.5％，比表面积(BET)≤15.7m2/g，101面微观内应变η≤2.8x10-3；SEM结果表明氢氧化镁颗粒为六方片状，具有规则的形貌，便于作为阻燃剂添加时容易分散。
3)大大的提高了氢氧化镁产物的纯度，使得产物的品质跟价值得以成倍的增长。
4)有效实现了重金属污泥中有价金属镁的综合回收，避免了现有回收工艺存在的镁在体系中循环、没有合适开路的不足(镁在酸浸后的浸出液中随浸出的钴镍锰一同作为原料液，对钴镍锰的回收利用造成干扰)；
5)整体回收工艺合理易行、效率高，具有可观经济价值。
附图说明
图1为本发明的工艺路程图。
具体实施方式
下面结合具体实施例对本发明作进一步说明。
实施例1
一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，包括以下步骤：
1.预处理水洗：将重金属污泥按照纯水与污泥干物质质量比8：1加入纯水，开电炉升温，边搅拌边用0.4g/L的稀硫酸水溶液调节pH至7.0(温度最后稳定在80℃，pH＝7.0是在此温度下测得)，继续搅拌10min，得水渣混合物经板框压滤脱水，得滤液1和滤渣1；将滤渣1用80-90℃热水洗涤过滤脱水1次，得滤液2。滤液1与滤液2合并所得滤液即为镁液。镁液中镁占重金属污泥中镁的比例达到99％以上，Ni的含量为0.5mg/L，Co、Mn、Zn未检出，Cu的含量为0.1mg/L，Na、Ca，Cl-虽然含量较高但是对制备氢氧化镁无害。
2.镁液除钙：
用1mol/L盐酸调节pH至2，加入磷酸二异辛酯萃取剂萃取，萃取时相比O/A(有机相与水相的体积比)＝1/1，进行2级逆流萃取，萃取温度为20℃，得到萃余液1。其中，磷酸二异辛酯萃取剂的制备方法为：用磺化煤油稀释至体积比20％，并用20％Wt的NaOH水溶液皂化，至皂化率达到30％。萃取相用pH＝3.5的稀盐酸洗涤2次，再用0.5mol/L盐酸进行1级反萃，反萃时的相比O/A＝2/1，反萃温度为20℃，主要目的使萃取剂得以重复利用。
3.镁液除硅：将萃余液1用2mol/L的氢氧化钠水溶液调节pH值至5.0，得到萃余液2,；向萃余液2中加聚合氯化铝和聚丙烯酰胺，按照每升萃余液2中加入5～15mg聚合氯化铝和0.1～0.5mg聚丙烯酰胺的比例加入；将温度控制在50℃，搅拌50min，用真空泵抽滤得滤液和少量滤渣，此滤液为精制镁液；滤渣用热水洗涤3-4次后排放。
4.加碱液沉镁：取步骤3中所得镁液2000ml，采用日本岛津原子吸收分光光度计AA-7000测量镁液中镁离子浓度，缓慢滴加5mol/L的NaOH水溶液，调节pH值至11.5，温度50℃，充分反应30min沉镁，即镁离子与氢氧根离子结合形成氢氧化镁沉淀，得到乳白色浊液。
5.表面改性：根据步骤4中镁液体积及镁液中镁离子浓度，计算步骤4中镁离子完全沉降时的氢氧化镁质量，向步骤4所得产物乳白色浊液中加入表面改性剂硬脂酸，所加硬脂酸质量占所计算的氢氧化镁质量的2％，在60℃条件下，对氢氧化镁改性70min。
6.陈化：将步骤5所得产物在65℃下陈化2h，陈化过程中调低搅拌速度至100～150r/min。
7.水热处理：将步骤6所得产物脱水，直至产物中氢氧化镁质量占步骤6所得产物质量30％，浓缩后所得浊液加入到内衬聚四氟乙烯、容积为1L的高压釜中，其中高压釜的填充度为75％，调整到温度至150℃，水热处理3h，得到渣样。
8.将步骤7所得渣样用真空泵抽滤脱水，使用热水与酒精交替洗涤，在100℃下烘干后制得高纯阻燃型氢氧化镁产品。
阻燃型氢氧化镁需要满足三点(参考标准HGT 4531-2013阻燃剂用氢氧化镁)：产品纯度≥93.0％，比表面积(BET)≤20.0m2/g，101面微观内应变η≤3.0x10-3；此外还需要产品氢氧化镁颗粒具有规则的形貌，便于作为阻燃剂添加时容易分散。
本实施例中镁的回收率(产物镁占重金属污泥中镁的比例)可达85.2％，产品纯度可达99.5％(由美国利曼ICP-OES电感耦合等离子发射光谱仪测得)，粒径分布在0.9-10.7μm之间，平均粒径D50：7.02μm(由马尔文2000激光粒度仪测得)，比表面积(BET)结果为15.7m2/g(美国NOVA全自动氮吸附比表面测试仪测得)，电镜(SEM)结果表明颗粒为六方片状(由美国FEI扫面电镜测得)，101面微观内应变η：2.8x10-3(全自动X射线衍射仪D/max-IIIA测得)，以下对测量设备不做赘述。
实施例2
一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，包括以下步骤：
1.预处理水洗：将重金属污泥按照纯水与污泥干物质质量比15：1加入纯水，开电炉升温，边搅拌边用0.6g/L的稀硫酸水溶液调节pH至8.0(温度最后稳定在85℃，pH＝8.0是在此温度下测得)，继续搅拌15min，得水渣混合物经板框压滤脱水，得滤液1和滤渣1；将滤渣1用80-90℃热水洗涤过滤脱水3次，得滤液2。滤液1与滤液2合并所得滤液即为镁液。镁液中镁占重金属污泥中镁的比例达到99％以上，Ni的含量为0.6mg/L，Co、Mn、Zn未检出，Cu的含量0.2mg/L，Na、Ca，Clˉ虽然含量较高但是对制备氢氧化镁无害。
2.镁液除钙：用5mol/L盐酸调节pH至3，加入磷酸二异辛酯萃取剂萃取，萃取时相比O/A(有机相与水相的体积比)＝1/2，进行4级逆流萃取，萃取温度为30℃，得到萃余液1。其中，磷酸二异辛酯萃取剂的制备方法为：用磺化煤油稀释至体积比30％，并用30％Wt的NaOH水溶液皂化，至皂化率达到40％。萃取相用pH＝4.5的稀盐酸洗涤2次，再用2.0mol/L盐酸进行1级反萃，反萃时的相比O/A＝1/1，反萃温度为30℃，主要目的使萃取剂得以重复利用。
3.镁液除硅：将萃余液1用5mol/L的氢氧化钠水溶液调节pH值至6.0，得到萃余液2,；向萃余液2中加聚合氯化铝和聚丙烯酰胺，按照每升萃余液2中加入15mg聚合氯化铝和0.5mg聚丙烯酰胺的比例加入；将温度控制在70℃，搅拌80min，用真空泵抽滤得滤液和少量滤渣，此滤液为精制镁液；滤渣用热水洗涤3-4次后排放。
4.加碱液沉镁：取步骤3中所得精致镁液2000ml，采用日本岛津原子吸收分光光度计AA-7000测量镁液中镁离子浓度，缓慢滴加4mol/L的NaOH水溶液，调节pH值至11.7，温度60℃，充分反应35min沉镁，即镁离子与氢氧根离子结合形成氢氧化镁沉淀，得到乳白色浊液。
5.表面改性：根据步骤4中镁液体积及镁液中镁离子浓度，计算步骤2中镁离子完全沉降时的氢氧化镁质量，向步骤2所得产物乳白色浊液中加入表面改性剂硬脂酸，所加硬脂酸质量占所计算的氢氧化镁质量的4％，在70℃条件下，对氢氧化镁改性90min；
6.陈化：将步骤5所得产物在70℃下陈化4h，陈化过程中调低搅拌速度至100～150r/min，得到乳白色浊液。
7.水热处理：将步骤6所得产物脱水，直至产物中氢氧化镁质量占步骤4所得产物质量的40％，浓缩后所得浊液加入到内衬聚四氟乙烯、容积为1L的高压釜中，其中高压釜的填充度为75％，调整到温度至180℃，水热处理5h，得到渣样。
8.将步骤7所得渣样用真空泵抽滤脱水，使用热水与酒精交替洗涤，在105℃下烘干后制得高纯阻燃型氢氧化镁产品。
本实施例中镁的回收率(产物镁占重金属污泥中镁的比例)可以达到85.7％，产品纯度可以达到99.8％，粒径分布在1.0-11.5μm之间，平均粒径8.15μm，BET结果为14.9m2/g，SEM结果表明颗粒为六方片状，101面微观内应变η：2.5x10-3。
实施例3
一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，包括以下步骤：
1.预处理水洗：将重金属污泥按照纯水与污泥干物质质量比10：1加入纯水，开电炉升温，边搅拌边用0.5g/L的稀硫酸水溶液调节pH至7.5(温度最后稳定在82℃，pH＝7.5是在此温度下测得)，继续搅拌12min，得水渣混合物经板框压滤脱水，得滤液1和滤渣1；将滤渣1用80-90℃热水洗涤过滤脱水2次，得滤液2。滤液1与滤液2合并所得滤液即为镁液。镁液中镁占重金属污泥中镁的比例达到99％以上，Ni的含量为0.3mg/L，Co、Mn、Zn未检出，Cu的含量0.1mg/L，Na、Ca，Clˉ虽然含量较高但是对制备氢氧化镁无害。
2.镁液除钙：用3mol/L盐酸调节pH至2.5，加入磷酸二异辛酯萃取剂萃取，萃取时相比O/A(有机相与水相的体积比)＝1/1.5，进行3级逆流萃取，萃取温度为25℃，得到萃余液1。其中，磷酸二异辛酯萃取剂的制备方法为：用磺化煤油稀释至体积比25％，并用25％Wt的NaOH水溶液皂化，至皂化率达到35％。萃取相用pH＝4.0的稀盐酸洗涤2次，再用1.0mol/L盐酸进行1级反萃，反萃时的相比O/A＝1.5/1，反萃温度为25℃，主要目的使萃取剂得以重复利用。
3.镁液除硅：将萃余液1用3mol/L的氢氧化钠水溶液调节pH值至5.5，得到萃余液2；向萃余液2中加聚合氯化铝和聚丙烯酰胺，按照每升萃余液2中加入10mg聚合氯化铝和0.2mg聚丙烯酰胺的比例加入；将温度控制在60℃，搅拌60min，用真空泵抽滤得滤液和少量滤渣，此滤液为精制镁液；滤渣用热水洗涤3-4次后排放。
4.加碱液沉镁：取步骤3中所得精制镁液2000ml，采用日本岛津原子吸收分光光度计AA-7000测量镁液中镁离子浓度，缓慢滴加4.5mol/L的NaOH水溶液，调节pH值至12.0，温度70℃，充分反应40min沉镁，即镁离子与氢氧根离子结合形成氢氧化镁沉淀，得到乳白色浊液。
5.表面改性：根据步骤4中镁液体积及镁液中镁离子浓度，计算步骤4中镁离子完全沉降时的氢氧化镁质量，向步骤4所得产物乳白色浊液中加入表面改性剂硬脂酸，所加硬脂酸质量占所计算的氢氧化镁质量的6％，在80℃条件下，对氢氧化镁改性100min；
6.陈化：将步骤5所得产物在80℃下陈化6h，陈化过程中调低搅拌速度至100～150r/min，得到乳白色浊液。
7.水热处理：将步骤6所得产物脱水，直至产物中氢氧化镁质量占步骤6所得产物质量的35％，浓缩后所得浊液加入到内衬聚四氟乙烯、容积为1L的高压釜中，其中高压釜的填充度为75％，调整到温度至170℃，水热处理8h，得到渣样。
8.将步骤7所得渣样用真空泵抽滤脱水，使用热水与酒精交替洗涤，在102℃下烘干后制得高纯阻燃型氢氧化镁产品。
本实施例中镁的回收率(产物镁占重金属污泥中镁的比例)可以达到85.5％，产品 纯度可以达到99.6％，粒径分布在1.1-11.7μm之间，平均粒径7.75μm，BET结果为14.4m2/g，SEM结果表明颗粒为六方片状，101面微观内应变η：2.6x10-3。

Claims (7)

  1. 一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于，包括以下步骤：
    步骤1，预处理水洗：将重金属污泥按照纯水与污泥干物质质量比8：1～15：1加入纯水，边加热边搅拌，加热至80～85℃并保温，在加热搅拌过程中加入0.4g/L～0.6g/L的稀硫酸直至在80～85℃测得pH为7.0～8.0，继续搅拌10～15min，得水渣混合物经板框压滤脱水，得滤液1和滤渣1；将滤渣1用热水洗涤过滤脱水1～3次，得滤液2；滤液1与滤液2合并所得滤液即为镁液；
    步骤2，镁液除钙：用1～5mol/L盐酸调节pH至2～3，加入磷酸二异辛酯萃取剂萃取，萃取时相比O/A＝1/1～1/2，进行2～4级逆流萃取，萃取温度为20～30℃，得到萃余液1；
    步骤3，镁液除硅：将萃余液1用2～5mol/L的氢氧化钠水溶液调节pH值至5.0～6.0，得到萃余液2，向萃余液2中加聚合氯化铝和聚丙烯酰胺，按照每升萃余液2中加入5～15mg聚合氯化铝和0.1～0.5mg聚丙烯酰胺的比例加入，温度控制在50～70℃，搅拌50～80min，用真空泵抽滤得滤液和滤渣，此滤液为精制镁液；
    步骤4，加碱液沉镁：取一定体积的步骤3中所得精制镁液，测量镁液中镁离子浓度，加入4～5mol/L的NaOH水溶液调节pH值至11.5～12.0，在温度50～70℃充分反应30-40min沉镁，得到乳白色浊液；
    步骤5，表面改性：根据步骤4中镁液体积及镁液中镁离子浓度，计算步骤4中镁离子完全沉降时的氢氧化镁质量，向步骤4所得产物乳白色浊液中加入表面改性剂硬脂酸，所加硬脂酸质量占所计算的氢氧化镁质量的2～6％，在60～80℃条件下，对氢氧化镁改性70～100min；
    步骤6，陈化：将步骤5所得产物在65～80℃下陈化2～6h，陈化过程中调低搅拌速度至100～150r/min；
    步骤7，水热处理：将步骤6所得产物脱水，直至产物中氢氧化镁质量占步骤6所得产物质量的30～40％，在高压釜中调整温度至150～180℃，水热处理3～8h，得到渣样；
    步骤8，将步骤7所得渣样用真空泵抽滤脱水、使用热水与酒精交替洗涤、在100-105℃下烘干后制得高纯阻燃型氢氧化镁产品。
  2. 根据权利要求1所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于：
    步骤1中，洗涤采用的热水的温度为80-90℃。
  3. 根据权利要求1或2所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于：
    步骤1中，将重金属污泥按照液固质量比15：1加入纯水；加热至85℃并保温；加0.6g/L的稀硫酸直至在85℃测得pH为8.0；继续搅拌15min；洗涤过滤脱水3次。
  4. 根据权利要求1或2所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的 方法，其特征在于：
    步骤2中，磷酸二异辛酯萃取剂的制备方法为：用磺化煤油稀释至体积比20～30％，并用20～30％Wt的NaOH水溶液皂化，至皂化率达到30～40％。
  5. 根据权利要求4所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于：
    步骤2中，萃取相用pH＝3.5～4.5的稀盐酸洗涤2次，再用0.5-2.0mol/L盐酸水溶液进行1级反萃，反萃时的相比O/A＝2/1～1/1，反萃温度为20～30℃。
  6. 根据权利要求4所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于：
    步骤4中，所述镁液中镁离子浓度由日本岛津原子吸收分光光度计AA-7000测得。
  7. 根据权利要求3所述的一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法，其特征在于：
    步骤7中，可采用板框压滤或真空泵抽滤脱水。
PCT/CN2017/090656 2016-08-30 2017-06-28 一种从重金属污泥中回收制备高纯阻燃型氢氧化镁的方法 WO2018040703A1 (zh)

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