CN101899264A - Rare earth polishing powder and preparation method thereof - Google Patents

Abstract

The invention discloses rare earth polishing powder and a preparation method thereof. The polishing powder comprises cerium oxide CeO2 and lanthanum oxide La2O3, wherein the total rare earth amount TREO is over 90 weight percent; and meanwhile, the cerium oxide CeO2 accounts for 75 to 80 percent and the lanthanum oxide La2O3 accounts for 20 to 25 percent of the total rare earth amount TREO of 739-2 type rare earth polishing powder. In order to ensure necessary grinding velocity, a fluorine F element having chemical action is added in a wet synthesis process and the initial forming of product granularity is controlled to make the grinding velocity higher and reduce the damage to a grinding surface.

Description

A kind of polishing powder from rare earth and manufacture method thereof

Technical field

The invention belongs to the rare-earth products preparation field, particularly a kind of polishing powder from rare earth and manufacture method thereof.

Background technology

Polishing powder from rare earth is widely used as the grinding of glass material etc. as a kind of novel abrasive substance, glass substrate of using as crystal works, water brill, CD, disk, LCD, HD etc.Using the every field of abrasive substance, more and more higher to the requirement of abrasive substance, comprise its performance, price.Especially in the polishing of crystal works, wrist-watch, electronic component etc., they are thrown based on manual mostly.Require grinding rate more and more faster, and reduce the damage of abrasive surface.At present, polishing powder is made probably dry method and two kinds of technologies of wet method.Dry method be directly rare-earth mineral pulverized, calcine, fluoridized, ball milling; Wet method is that re chloride that rare-earth mineral is made through sulfuric acid baking, water logging, organic solvent extraction is through synthetic, calcining, wet classification.Raw material is formed mainly with cerium oxide CeO2, lanthanum trioxide La ₂O ₃, Praseodymium trioxide Pr ₆O ₁₁, Neodymium trioxide Nd ₂O ₃Be main.Because rare earth mineral resources in short supply, the price of Praseodymium trioxide, Neodymium trioxide is the fault wall liter not in recent years.With lanthanum, cerium, praseodymium, neodymium is that raw material making polishing powder is more and more difficult.In view of the situation, having invented with sufficient lanthanum, cerium on the market is the polishing powder from rare earth of raw material.And the grinding rate that has guaranteed it is fast and the polishing powder from rare earth of higher abrasive surface precision, has reduced the abrasive substance cost, has effectively utilized rare earth resources.

Summary of the invention

The purpose of this invention is to provide a kind of is that raw material manufacturing grinding rate is higher with lanthanum, cerium, and polishing powder from rare earth and manufacture method thereof still less takes place in damage.

For achieving the above object, a kind of polishing powder from rare earth of the present invention, among the total amount of rare earth TREO of polishing powder from rare earth, cerium oxide CeO ₂The ratio of content accounts for 73-80%, lanthanum trioxide La ₂O ₃The ratio of content accounts for 20-25%, Praseodymium trioxide Pr ₆O ₁₁Content ratio 1%; Neodymium trioxide Nd ₂O ₃Content ratio 0.2%.

The manufacture method of above-mentioned a kind of polishing powder from rare earth, realize by following steps:

One, with cerium oxide CeO ₂The ratio of content accounts for 73-80%, lanthanum trioxide La ₂O ₃The ratio of content accounts for 20-25%, Praseodymium trioxide Pr ₆O ₁₁Content ratio 1%; Neodymium trioxide Nd ₂O ₃Content ratio 0.2% is mixed with few neodymium rare earth chloride solution raw material for standby with water;

Two, with neutralizing agent ammoniacal liquor NH ₃H ₂The pH value to 4.0 of few neodymium rare earth chloride stock liquid of O regulating step one preparation carries out plate-and-frame filter press then and filters, and removes non-rare earth impurities such as thorium, iron, slag, and it is standby to put into storage tank;

Three, be that 45% silicofluoric acid and content are that 93% sulfate additive is together put into the enamel steel basin at first with few neodymium rare earth chloride stock liquid of making in the step 2 with content, precipitate when being warming up to 85 ℃～95 ℃ after stirring, precipitation agent is selected bicarbonate of ammonia NH for use ₄HCO ₃, because the adding speed of precipitation agent directly influences sedimentary nucleation rate, precipitin reaction is fast, and nucleation rate is fast, and particle is difficult for growing up, so sedimentation time was controlled at 2 hours;

Four, etc. after the precipitation of step 3 is finished, will lack the neodymium rare earth chloride solution and boil 1h through 85 ℃～95 ℃, and impel throw out to change the subcarbonate that helps rubbing down into, the ultrafine powder of flush away trace and excessive ammonium chloride NH in washing bath by carbonate ₄Cl;

Five, the few neodymium rare earth chloride solution that step 4 is made is crossed moisture content through vacuum filtering system, carry out roasting with tunnel furnace,, temperature is controlled at 900 ℃-980 ℃, roasting time is 5-7h, after the roasting, material and 4 parts of pure water are sized mixing, and carry out classification through 500 order wet method vibration screening then, the spray-dried machine spraying gun of slip is injected into vaporific, remove moisture 500 ℃ of following moments, the gained material carries out the dry method size classification with the dry classification machine again, obtains to meet the polishing powder from rare earth of granularity requirements.

Study repeatedly by grinding rate, damage, determined lanthanum, cerium amount control regulation ratio, globule size, technical process polishing powder from rare earth.Then grinding rate is higher, damages forr a short time, and finishes the present invention thus.Its characteristics are that laser diffractometry volume average particle size D50 is 1.5um～2.5um, and the granular size of polishing powder has directly determined polishing velocity and polished the grinding effect that can reach; The damage occurrence degree height though the too big grinding rate of granularity is fast; The too little grinding rate of granularity is slow but the damage occurrence degree is low, and be prone to clean bad; Glass hard (HRC65s such as crystal works, wrist-watch, electronic component are bigger, must guarantee that it has better hardness and chemically reactive.Cerium oxide CeO2 content accounts for 75wt%-80wt% in the ratio of total amount of the rare earth oxide TREO in the raw material, can make to have the polishing powder from rare earth that requires level more than the performance.Therefore, be that benchmark carries out particle diameter and is set at 1.5um-2.5um with laser diffractometry volume average particle sizes D50, the particle state of polishing powder from rare earth is controlled, thereby produces the polishing powder from rare earth of adaptation.

As mentioned above, the better scope of laser diffractometry volume average particle size D50 is 1.5un-2.5um, and this volume average particle sizes D50 is lower than lower value, and then rubbing down speed does not reach application requiring; If exceed higher limit, then in application, can scratch the lapped face of polished object, even finish grind, also be to be difficult for eliminating in later process.Therefore, the factor of comprehensive two aspects, the long-pending mean particle size D 50 of laser diffractometry Ma Er style preferably is controlled at 1.5um-2.5um.

Polishing powder from rare earth, its rare earth oxide TREO total amount is better more than 90wt%, in each component proportions one of rare earth regularly, the ratio of cerium oxide CeO2 content and rare earth oxide TREO total amount is big more, then the ratio of cerium oxide CeO2 in the polishing powder composition is just big more, the content of other impurity is just low more, thereby can effectively reduce the generation that scratches phenomenon.Result of study shows that the ratio of cerium oxide CeO2 content in rare earth oxide TREO total amount preferably is controlled at 75wt%-80wt%, and the ratio of cerium oxide is high more, is easy to generate cut more, if exceed the upper limit, scratches the polished object lapped face; The ratio of cerium oxide is low more, and then rubbing down speed can be affected.Praseodymium trioxide Pr ₆O ₁₁, Neodymium trioxide Nd ₂O ₃Content in the ratio control of total amount of the rare earth oxide TREO at trace.

Fluorine F content generally is controlled at 4wt%-6wt% in the ratio of total amount of the rare earth oxide TREO, and the ratio of fluorine F content is high more, and then the chemical action on the rubbing down surface is strong more, causes the lapped face roughness big, causes grinding effect on the low side.If exceed the upper limit, in use rough interface can appear in the rubbing down surface, mainly is because the result of chemical action; Owing to the reduction of rubbing down speed along with fluorine F content reduces, so fluorine F content ratio is lower than lower limit, then reduce grinding rate greatly, mainly be that the chemical action effect is faint; Therefore, the factor of comprehensive two aspects, fluorine F content preferably is controlled at 4.5wt%-5.5wt% in the ratio of total amount of the rare earth oxide TREO.Fluorine F element plays important effect in the polishing powder from rare earth polishing process, it directly influences the formation of crystalline structure, and participation chemisorption, the introducing of fluorine F element is to be additive by silicofluoric acid and sulfuric acid in the polishing powder from rare earth, with the ammonium bicarbonate soln is precipitation agent, form fluorine carbonated rare earth intermediate with rare earth, in roasting process, form a kind of fluorine F atmosphere, facilitate the formation of product; The fluorine F ion that has only trace is with cerous fluoride CeF ₃Form in finished product, generate; This polishing powder experiences twice crystal grain and makes brilliant process, forms the rare earth fluoro carbonate precursor particle that does not have mill capacity fully for the first time, and for the second time through high-temperature roasting, circular configuration is originally partly destroyed, and forms the product that meets application requiring.Be the research situation to repeatedly roasting below, consequently: the maturing temperature of polishing powder from rare earth better is controlled at 900 ℃-980 ℃, and maturing temperature is lower than lower value, and then the particle diameter of polishing powder can not become greatly in the sintering procedure, causes rubbing down speed to descend; If maturing temperature is higher, the particle diameter of output powder is big, scratches easily in application by the lapped face of grinding element; Therefore, the factor of comprehensive two aspects, maturing temperature preferably is controlled at 900 ℃-980 ℃.Roasting time was controlled at 5-7 hour, and roasting time is lower than lower value, and particle transforms not exclusively, and hardness reduces, and cutting force descends; Roasting time is higher than higher limit, and particle aggregation is serious, and abrasion loss increases.

Embodiment

At first prepare few neodymium rare earth chloride solution raw material, its rare earth component is cerium oxide CeO ₂The ratio of content accounts for 75-80%, lanthanum trioxide La ₂O ₃The ratio of content accounts for 20-25%, Praseodymium trioxide Pr ₆O ₁₁Content ratio is less than 1%; Neodymium trioxide Nd ₂O ₃Content ratio is less than 0.2%.

Earlier with neutralizing agent ammoniacal liquor NH ₃H ₂O regulates the pH value to 4.0 of stock liquid, carries out plate-and-frame filter press then and filters, and removes non-rare earth impurities such as thorium, iron, slag, and it is standby to put into storage tank; Make the polishing powder from rare earth presoma with ready prepd few neodymium rare earth chloride solution raw material: at first be that the few neodymium rare earth chloride solution 850L of 198g/L and content are that 45% silicofluoric acid 10L and content are that 93% sulfate additive 6L together puts into the enamel steel basin with the content for preparing, precipitate when being warming up to 85 ℃～95 ℃ after stirring, precipitation agent is selected bicarbonate of ammonia NH for use ₄HCO ₃Because the adding speed of precipitation agent directly influences sedimentary nucleation rate, precipitin reaction is fast, and nucleation rate is fast, and particle is difficult for growing up, so sedimentation time was controlled at 2 hours; After precipitin reaction is finished, boil 1h through 85 ℃～95 ℃, impel throw out to change the subcarbonate that helps rubbing down into, the ultrafine powder of flush away trace and excessive ammonium chloride NH in washing bath by carbonate ₄Cl, ammonium chloride NH ₄Cl content is less than 15g/L; Cross moisture content through vacuum filtering system, carry out roasting with tunnel furnace,, temperature is controlled at 900 ℃-980 ℃, roasting time is 5-7h, after the roasting, material and 4 parts of pure water are sized mixing, and 500 order wet method vibration screening are carried out classification, the spray-dried machine spraying gun of slip is injected into vaporific, remove moisture 500 ℃ of following moments, the gained material carries out the dry method size classification with the dry classification machine again, obtains to meet the polishing powder from rare earth of granularity requirements.

Claims (2)

1. polishing powder from rare earth is characterized in that: among the total amount of rare earth TREO of polishing powder from rare earth, and cerium oxide CeO ₂The ratio of content accounts for 73-80%, lanthanum trioxide La ₂O ₃The ratio of content accounts for 20-25%, Praseodymium trioxide Pr ₆O ₁₁Content ratio 1%; Neodymium trioxide Nd ₂O ₃Content ratio 0.2%.

2. the manufacture method of a kind of polishing powder from rare earth according to claim 1 is characterized in that: the manufacture method of above-mentioned polishing powder from rare earth, realize by following steps,

One, with cerium oxide CeO ₂The ratio of content accounts for 73-80%, lanthanum trioxide La ₂O ₃The ratio of content accounts for 20-25%, Praseodymium trioxide Pr ₆O ₁₁Content ratio 1%; Neodymium trioxide Nd ₂O ₃Content ratio 0.2% is mixed with few neodymium rare earth chloride solution raw material for standby with water;

Two, with neutralizing agent ammoniacal liquor NH ₃H ₂The pH value to 4.0 of few neodymium rare earth chloride stock liquid of O regulating step one preparation carries out plate-and-frame filter press then and filters, and removes non-rare earth impurities such as thorium, iron, slag, and it is standby to put into storage tank;

Three, be that 45% silicofluoric acid and content are that 93% sulfate additive is together put into the enamel steel basin at first with few neodymium rare earth chloride stock liquid of making in the step 2 with content, precipitate when being warming up to 85 ℃～95 ℃ after stirring, precipitation agent is selected bicarbonate of ammonia NH for use ₄HCO ₃, because the adding speed of precipitation agent directly influences sedimentary nucleation rate, precipitin reaction is fast, and nucleation rate is fast, and particle is difficult for growing up, so sedimentation time was controlled at 2 hours;

Four, etc. after the precipitation of step 3 is finished, will lack the neodymium rare earth chloride solution and boil 1h through 85 ℃～95 ℃, and impel throw out to change the subcarbonate that helps rubbing down into, the ultrafine powder of flush away trace and excessive ammonium chloride NH in washing bath by carbonate ₄Cl, ammonium chloride NH ₄Cl content is less than 15g/L;

Five, the few neodymium rare earth chloride solution that step 4 is made is crossed moisture content through vacuum filtering system, carry out roasting with tunnel furnace,, temperature is controlled at 900 ℃-980 ℃, roasting time is 5-7h, after the roasting, material and 4 parts of pure water are sized mixing, and carry out classification through 500 order wet method vibration screening then, the spray-dried machine spraying gun of slip is injected into vaporific, remove moisture 500 ℃ of following moments, the gained material carries out the dry method size classification with the dry classification machine again, obtains to meet the polishing powder from rare earth of granularity requirements.