These dynamics helped drive sales of $453 million, an increase of 5% sequentially and up 8% compared to last year.
Generated $59 million of operating income and earnings per share of $1.17, up 4% and a record first quarter earnings per share for our company.
In addition, cash from operations and free cash flow were up 68% and 142% respectively over last year.
Steel markets further improved from the fourth quarter with utilization rates reaching close to 80% in the US, and our paper end markets continue to rebound from a slow 2020.
Performance Materials, sales in our Household Personal Care and Specialty business increased 14% driven by our Global Pet Care platform, but also double-digit increases in other specialty applications that we've been investing in to enhance our technology and manufacturing capabilities, including Fabric Care, Personal Care and edible oil purification.
Metalcasting business performed well, as sales grew 32% driven by strong demand in both North America and Asia from foundries serving automotive, heavy truck, and agriculture markets.
Specifically, Metalcasting sales in Asia were up 52% over 2020 with much of this growth coming in China.
Penetration of our blended products has also accelerated in China, and sales increased 62% compared to last year.
Last quarter in India, which is this -- which is the second largest casting market globally, sales of our blended products were up 21% over 2020.
Within our Specialty Minerals segment, our Specialty PCC business had another strong quarter with sales up 17% over last year.
Paper PCC sales increased 5% driven by improving end market conditions and the ramp up of new satellites.
Finishing up our sales highlights, our refractory segment had a great quarter with sales increasing 7% over 2020 and margins remaining at 16.2%.
We see margins above 14% in the second quarter, and have the potential to move higher toward the second half of the year with continued improvement across our businesses.
Overall sales in the first quarter were 5% higher sequentially and 8% higher than the prior year as the majority of our end markets remained strong and each of our segments grew sales versus the prior year, now that we combined the Energy Services segment into environmental products within the Performance Materials segment this quarter.
Operating income was $58.8 million or 1% higher than the prior year.
Lower contribution from these businesses had an unfavorable impact on our margin of approximately 80 basis points in the quarter.
This is a normal adjustment we make every quarter, and we are calling it out today because of the size of the variance, which was approximately $3.5 million year-over-year.
Adjusting for these impacts, the rest of MTI grew operating margin by 60 basis points over the prior year.
In addition, we continue to drive productivity with a 6% year-over-year improvement in the number of hours worked per ton.
Earnings per share of $1.17 was a record for our first quarter, and was 4% above prior year and 8% above the fourth quarter, excluding special items.
Our effective tax rate for the quarter was 18% and we expect our full year effective tax rate to be approximately 20%.
First quarter sales for Performance Materials were $230.9 million, 5% higher sequentially and 9% higher than the prior year.
Metalcasting sales increased 6% sequentially and 32% versus the prior year as foundry demand remained strong in both North America and China.
Household, Personal Care, and Specialty product sales increased 7% sequentially and 14% versus the prior year on double-digit growth across several consumer-oriented product lines.
Building material sales grew 11% sequentially and were 18% lower than the prior year as project activity started to increase late in the first quarter.
Meanwhile, environmental products moved through a challenging quarter with sales down 4% sequentially and 29% versus the prior year.
Operating income for the segment was $29.8 million, 9% higher than the prior year.
Operating margin was 12.9% of sales, at the same level as the prior year.
Excluding Environmental Products and Building Materials, which had a weaker quarter than last year, operating margins for the rest of this segment were above 15% in the quarter.
Specialty Mineral sales were $147.8 million in the first quarter, 6% higher sequentially and 8% higher than the prior year.
Paper PCC sales were 8% higher sequentially and 5% higher than the prior year, as paper mill operating rates continue to improve and all regions grew sales sequentially.
Specialty PCC sales increased 4% sequentially and 17% versus the prior year as automotive, construction, and consumer demand remains strong.
Process Mineral sales increased 5% sequentially and 10% versus the prior year on strength in residential construction and automotive markets.
Segment operating income was $21.1 million, 4% higher than the prior year.
Operating margin was 14.3% of sales, and was temporarily impacted by seasonally higher energy costs.
Refractory segment sales were $73.9 million in the first quarter, at same level as the fourth quarter, and 7% higher than the prior year, as continued improvement in steel mill utilization rates was offset by fewer laser measurement equipment sales compared to the fourth quarter.
Segment operating income was $12 million and represented 16.2% of sales compared to 15% in the fourth quarter and 16.2% in the prior year.
Mill utilization rates improved to 78% in North America and 72% in Europe in the first quarter, up from 75% and 70% respectively in the fourth quarter.
First quarter cash from operations was $51 million versus $30 million in the prior year, and free cash flow was $33 million versus $14 million in the prior year.
We deployed $18 million of capital during the quarter to grow the business, develop our mines, and improve our operations.
We used a portion of free cash flow to repurchase $20 million of shares in the first quarter, and we have repurchased $37 million so far under our current $75 million program.
The company is in a solid financial position with over $650 million of liquidity and a net leverage ratio of 1.8 times EBITDA.
Now from an operating margin perspective, we expect to return to above 14% of sales as we continue to implement pricing actions, proactively manage inflationary cost increases, and drive productivity improvements.
As I touched on earlier, our portfolio of consumer products which represents approximately 25% of our total sales, remains a key part of our growth strategy, and we delivered double-digit sales increases in these core business.
The first quarter sales in Asia increased 33% with all of our major countries contributing.
Specific highlight in the quarter was our PCC growth where we signed a contract with buying paper for a 50,000 ton satellite in China, which should be operational in the second quarter of 2022.
200,000 tons of new production capacity that came online at the end of last year in China and India will further contribute to volume growth this year as they fully ramp up.
We're also on track to commission two additional satellites this year totaling over 70,000 tons, one for our packaging application in Europe and another for a standard PCC plant in India.
[Indecipherable] mention our new product pipeline, our total portfolio comprises over 300 products from early stage development to commercialization, representing around $800 million of revenue at full potential.
This is an increase of about 30% compared to where we were two years ago.

Summary:
These dynamics helped drive sales of $453 million, an increase of 5% sequentially and up 8% compared to last year.
Generated $59 million of operating income and earnings per share of $1.17, up 4% and a record first quarter earnings per share for our company.
Earnings per share of $1.17 was a record for our first quarter, and was 4% above prior year and 8% above the fourth quarter, excluding special items.