阅读说明：本技术 一种锂盐的高效回收方法 (High-efficiency lithium salt recovery method ) 是由 杨雄强 莫燕娇 张帆 甘永兰 于 2020-06-19 设计创作，主要内容包括：本发明公开了一种锂盐的高效回收方法,包括以下步骤：按照一定的比例取锂渣和副产品硫酸钠混合均匀后置于焙烧炉中；升温焙烧得到硅酸钠熟料和三氧化硫气体；将三氧化硫气体通入水中吸收得到硫酸,将该硫酸通入锂矿酸化系统中循环利用；将硅酸钠熟料和水按照混合后浸出；加入除杂剂将杂质去除后,压滤得到硅酸钠净化液和浸出渣；将硅酸钠净化液加热浓缩成为硅酸钠产品,将浸出渣返回锂矿焙烧系统利用。本发明的方法实现了锂盐生产过程中,锂元素理论上100％的回收率,且锂渣和副产品Na<Sub>2</Sub>SO<Sub>4</Sub>最大价值资源化利用,锂盐生产工艺做到闭路循环,体现了锂盐生产的绿色环保、低成本、高收益的先进工艺方法。(The invention discloses a method for efficiently recovering lithium salt, which comprises the following steps: uniformly mixing the lithium slag and the byproduct sodium sulfate according to a certain proportion, and placing the mixture in a roasting furnace; heating and roasting to obtain sodium silicate clinker and sulfur trioxide gas; introducing sulfur trioxide gas into water to absorb to obtain sulfuric acid, and introducing the sulfuric acid into a lithium ore acidification system for cyclic utilization; mixing and leaching the sodium silicate clinker with water; adding an impurity removing agent to remove impurities, and performing filter pressing to obtain a sodium silicate purification solution and leaching residues; heating and concentrating the sodium silicate purifying solution to obtain a sodium silicate product, and returning the leaching residue to a lithium ore roasting system for utilization. The method realizes the theoretical 100 percent recovery rate of the lithium element in the production process of the lithium salt, and the lithium slag and the by-product Na 2 SO 4 The maximum value is utilized as resources, the lithium salt production process realizes closed cycle, and embodiesThe lithium salt production is an advanced process method which is green, environment-friendly, low in cost and high in yield.)

1. A method for efficiently recovering a lithium salt is characterized by comprising the following steps: the method comprises the following steps:

(1) preparing materials: uniformly mixing the lithium slag and the byproduct sodium sulfate according to a certain proportion, and placing the mixture in a roasting furnace;

(2) roasting: heating the roasting furnace to high temperature for roasting for a period of time to obtain separation of sodium silicate clinker and sulfur trioxide gas;

(3) absorption: introducing the sulfur trioxide gas in the step (2) into water to absorb to obtain sulfuric acid, and introducing the sulfuric acid into a lithium ore acidification system for recycling;

(4) leaching: mixing and stirring the sodium silicate clinker and water in the step (2) uniformly according to a certain mass ratio, and standing for leaching to obtain layered upper-layer solution and extract;

(5) And (3) filter pressing: adding an impurity removing agent into the upper solution and the extract obtained in the step (4) to remove impurities, and performing filter pressing to obtain a sodium silicate purification solution and extract residues;

(6) and (3) recovering: heating and concentrating the sodium silicate purifying solution to obtain a sodium silicate product, and returning the leaching residue to a lithium ore roasting system for utilization.

2. The method for recovering lithium salt of claim 1, wherein: in the step (1), SiO in the lithium slag₂The content of the lithium slag is 70-80%, and the proportion of the lithium slag and the byproduct sodium sulfate is 1 (1-2).

3. The method for recovering lithium salt of claim 1, wherein: in the step (2), the roasting temperature is 1300-1500 ℃, and the roasting time is 3-8 h.

4. The method for recovering lithium salt of claim 1, wherein: in the step (3), the aeration rate of the sulfur trioxide gas is 5 to 15m³/h。

5. The method for recovering lithium salt of claim 1, wherein: in the step (4), the ratio of the sodium silicate clinker to the water is 1: (2-5).

6. The method for recovering lithium salt of claim 1, wherein: in the step (5), the impurities are metal ions, and the impurity removing agent is sodium sulfide and hydrogen peroxide.

7. The method of claim 6, wherein the lithium salt is recovered at a high efficiency, and the method comprises the steps of: the addition amount of the sodium sulfide is 0.3-0.8%, the addition amount of the hydrogen peroxide is 0.1-0.5%, the reaction temperature is controlled to be 40-80 ℃, and the reaction time is 0.5-2 h.

8. The method for recovering lithium salt of claim 1, wherein: in the step (6), the heating concentration is evaporation concentration of water after boiling, and the concentration is 20-50 times of concentration.

Technical Field

The invention relates to the technical field of recycling of lithium salt byproducts and lithium slag, in particular to a high-efficiency lithium salt recovery method.

Background

In recent years, with the rapid development of the new energy automobile industry, the development of the lithium battery field is more and more rapid, more and more enterprises invest in the exploitation and utilization of spodumene, and the problems of resource waste, large slag quantity, overhigh production cost or insignificant economic benefit and the like generally exist in the production process of lithium salt.

At present, a concentrated sulfuric acid-sodium carbonate method is mainly adopted to produce lithium carbonate, natural spodumene is roasted at a high temperature of 1000 ℃, concentrated sulfuric acid is added to acidify and roast, water is added to leach out after full reaction, calcium carbonate is added to adjust the pH value, and finally sodium carbonate is added to obtain the lithium carbonate. The process generates a large amount of lithium slag and sodium sulfate by-products, and the lithium slag is mostly stacked in a yard built by the factory or sent to a cement plant or a ceramic plant to be used as an additive to be applied to cement admixtures and ceramic materials. Because the recovery rate of lithium is not high in the production process of lithium salt and the residual lithium amount of the lithium slag is large, a large amount of lithium slag causes waste of lithium resources, and the value of the lithium slag as an additive such as cement is too low. And SiO in the lithium slag₂The content is very high, and the waste can be changed into valuable materials by utilization; in addition, Na is produced as a by-product in the production of lithium salts₂SO₄And the treatment is low in price, so that the overall economic benefit of lithium salt production enterprises is not obvious. In view of the above problems, it is necessary to explore a resource recycling method in the lithium salt production process.

Disclosure of Invention

The invention aims to: aiming at the problems, the resource recycling method for reducing cost and improving efficiency in the lithium salt production process is provided, and SiO in lithium slag is utilized in the method₂And by-product Na₂SO₄Roasting at high temperature to obtain sodium silicate clinker and SO₃A gas. SO (SO)₃Absorbing the gas to obtain sulfuric acid, returning the sulfuric acid to the lithium ore acidification system for cyclic utilization, adding water to the sodium silicate clinker for leaching, removing impurities and filter-pressing to obtain sodium silicate purified liquidAnd leaching residues, wherein the sodium silicate solution is concentrated to obtain a high-value sodium silicate product, and the leaching residues are treated to enrich lithium elements and can be returned to a lithium salt production system for continuous utilization. The method realizes the theoretical 100% recovery rate of lithium element in the production process of lithium salt, and lithium slag and by-product Na₂SO₄The maximum value is utilized as resources, the lithium salt production process achieves closed cycle, and the advanced process method which is green, environment-friendly, low in cost and high in yield and used for producing the lithium salt is embodied.

In order to achieve the purpose of the invention, the technical scheme adopted by the invention is as follows:

a method for efficiently recovering a lithium salt, comprising the steps of:

(1) preparing materials: uniformly mixing the lithium slag and the byproduct sodium sulfate according to a certain proportion, and placing the mixture in a roasting furnace;

(2) Roasting: heating the roasting furnace to high temperature for roasting for a period of time to obtain separation of sodium silicate clinker and sulfur trioxide gas;

(3) absorption: introducing the sulfur trioxide gas in the step (2) into water to absorb to obtain sulfuric acid, and introducing the sulfuric acid into a lithium ore acidification system for recycling;

(4) leaching: mixing and stirring the sodium silicate clinker and water in the step (2) uniformly according to a certain mass ratio, and standing for leaching to obtain layered upper-layer solution and extract;

(5) and (3) filter pressing: adding an impurity removing agent into the upper solution and the extract obtained in the step (4) to remove impurities, and performing filter pressing to obtain a sodium silicate purification solution and extract residues;

(6) and (3) recovering: heating and concentrating the sodium silicate purifying solution to obtain a sodium silicate product, and returning the leaching residue to a lithium ore roasting system for utilization.

Further, in the step (1), SiO in the lithium slag₂The content of the lithium slag is 70-80%, and the proportion of the lithium slag and the byproduct sodium sulfate is 1 (1-2).

Further, in the step (2), the roasting temperature is 1300-1500 ℃, and the roasting time is 3-8 h.

Further, in the step (3), the aeration rate of the sulfur trioxide gas is 5 to 15m³/h。

Further, in the step (4), the ratio of the sodium silicate clinker to the water is 1: (2-5).

Further, in the step (5), the impurities are metal ions, and the impurity removing agent is sodium sulfide and hydrogen peroxide.

Furthermore, the adding amount of the sodium sulfide is 0.3-0.8%, the adding amount of the hydrogen peroxide is 0.1-0.5%, the reaction temperature is controlled to be 40-80 ℃, and the reaction time is 0.5-2 h.

Further, in the step (6), the heating concentration is evaporation concentration of water after boiling, and the concentration is 20 to 50 times of concentration.

In summary, due to the adoption of the technical scheme, the invention has the beneficial effects that:

the method utilizes SiO in the lithium slag₂And by-product sodium sulfate is roasted at high temperature to obtain sodium silicate clinker and sulfur trioxide gas. The sulfur trioxide gas is absorbed to obtain sulfuric acid, the sulfuric acid is returned to a lithium ore acidification system for recycling, the sodium silicate clinker is leached by adding water, impurities are removed, and filter pressing is carried out to obtain sodium silicate purification liquid and leaching residues, the sodium silicate solution is concentrated to obtain a high-value sodium silicate product, and the leaching residues are subjected to the treatment, so that the lithium element is enriched and can be returned to a lithium salt production system for continuous utilization. The method realizes the theoretical 100% recovery rate of lithium element in the lithium salt production process, the maximum value of the lithium slag and the byproduct sodium sulfate is recycled, the lithium salt production process realizes closed cycle, and the advanced process method which is green, environment-friendly, low in cost and high in yield is embodied in the lithium salt production.

Drawings

FIG. 1 is a process flow diagram of the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail below with reference to preferred embodiments. It should be noted, however, that the numerous details set forth in the description are merely for the purpose of providing the reader with a thorough understanding of one or more aspects of the present invention, which may be practiced without these specific details.